Jersey 1.1.2-ea User Guide

Table of Contents

1. Overview of JAX-RS 1.1
1.1. Root Resource Classes
1.1.1. @Path
1.1.2. HTTP Methods
1.1.3. @Produces
1.1.4. @Consumes
1.2. Deploying a RESTful Web Service
1.3. Extracting Request Parameters
1.4. Represetations and Java Types
1.5. Building Responses
1.6. Sub-resources
1.7. Building URIs
1.8. WebApplicationException and Mapping Exceptions to Responses
1.9. Conditional GETs and Returning 304 (Not Modified) Responses
1.10. Life-cycle of Root Resource Classes
1.11. Security
1.12. Rules of Injection
1.13. Use of @Context
1.14. Annotations Defined By JAX-RS
2. JSON Support
2.1. JAXB Based JSON support
2.1.1. Configuration Options
2.1.2. JSON Notations
2.1.3. Examples
2.2. Low-Level JSON support
2.2.1. Examples

List of Examples

1.1. Simple hello world root resource class
1.2. Specifying URI path parameter
1.3. PUT method
1.4. Specifying output MIME type
1.5. Using multiple output MIME types
1.6. Specifying input MIME type
1.7. Deployment agnostic application model
1.8. Reusing Jersey implementation in your custom application model
1.9. Deployment of your application using Jersey specific servlet
1.10. Using Jersey specific servlet without an application model instance
1.11. Query parameters
1.12. Custom Java type for consuming request parameters
1.13. Processing POSTed HTML form
1.14. Obtaining general map of URI path and/or query parameters
1.15. Obtaining general map of header parameters
1.16. Obtaining general map of form parameters
1.17. Using File with a specific MIME type to produce a response
1.18. The most acceptable MIME type is used when multiple output MIME types allowed
1.19. Returning 201 status code and adding Location header in response to POST request
1.20. Adding an entity body to a custom response
1.21. Sub-resource methods
1.22. Sub-resource locators
1.23. URI building
1.24. Building URIs using query parameters
1.25. Throwing Jersey specific exceptions to control response
1.26. Jersey specific exception implementation
1.27. Mapping generic exceptions to responses
1.28. Conditional GET support
1.29. Accessing SecurityContext
1.30. Injection
2.1. Simple JAXB bean implementation
2.2. JAXB bean used to generate JSON representation
2.3. Tweaking JSON format using JAXB
2.4. An example of a JAXBContext resolver implementation
2.5. JAXB beans for JSON supported notations description, simple address bean
2.6. JAXB beans for JSON supported notations description, contact bean
2.7. JAXB beans for JSON supported notations description, initialization
2.8. JSON expression produced using mapped notation
2.9. Force arrays in mapped JSON notation
2.10. Force non-string values in mapped JSON notation
2.11. XML attributes as XML elements in mapped JSON notation
2.12. Keep XML root tag equivalent in JSON mapped JSON notation
2.13. XML root tag equivalent kept in JSON using mapped notation
2.14. XML namespace to JSON mapping configuration for mapped notation
2.15. JSON expression produced using natural notation
2.16. Keep XML root tag equivalent in JSON natural JSON notation
2.17. JSON expression produced using Jettison based mapped notation
2.18. XML namespace to JSON mapping configuration for Jettison based mapped notation
2.19. JSON expression with XML namespaces mapped into JSON
2.20. JSON expression produced using badgerfish notation
2.21. JAXB bean creation
2.22. Constructing a JSONObject


This doc is yet in a very early state. We want to create here sort of a user guide for jersey users, which will get versioned together with jersey code base.

More content to come soon...

Chapter 1. Overview of JAX-RS 1.1

This chapter presents an overview of the JAX-RS 1.1 features.

The JAX-RS 1.1 API may be found online here.

The JAX-RS 1.1 specification draft may be found online here.

1.1. Root Resource Classes

Root resource classes are POJOs (Plain Old Java Objects) that are annotated with @Path have at least one method annotated with @Path or a resource method designator annotation such as @GET, @PUT, @POST, or @DELETE. Resource methods are methods of a resource class annotated with a resource method designator. This section shows how to use Jersey to annotate Java objects to create RESTful web services.

The following code example is a very simple example of a root resource class using JAX-RS annotations. The example code shown here is from one of the samples that ships with Jersey, the zip file of which can be found in the maven repository here.

Example 1.1. Simple hello world root resource class

  1 package;
  3 import;
  4 import;
  5 import;
  7 // The Java class will be hosted at the URI path "/helloworld"
  8 @Path("/helloworld")
  9 public class HelloWorldResource {
 11     // The Java method will process HTTP GET requests
 12     @GET
 13     // The Java method will produce content identified by the MIME Media
 14     // type "text/plain"
 15     @Produces("text/plain")
 16     public String getClichedMessage() {
 17         // Return some cliched textual content
 18         return "Hello World";
 19     }
 20 }

Let's look at some of the JAX-RS annotations used in this example.

1.1.1. @Path

The @Path annotation's value is a relative URI path. In the example above, the Java class will be hosted at the URI path /helloworld. This is an extremely simple use of the @Path annotation. What makes JAX-RS so useful is that you can embed variables in the URIs.

URI path templates are URIs with variables embedded within the URI syntax. These variables are substituted at runtime in order for a resource to respond to a request based on the substituted URI. Variables are denoted by curly braces. For example, look at the following @Path annotation:


In this type of example, a user will be prompted to enter their name, and then a Jersey web service configured to respond to requests to this URI path template will respond. For example, if the user entered their username as "Galileo", the web service will respond to the following URL:

To obtain the value of the username variable the @PathParam may be used on method parameter of a request method, for example:

Example 1.2. Specifying URI path parameter

  1 @Path("/users/{username}")
  2 public class UserResource {
  4     @GET
  5     @Produces("text/xml")
  6     public String getUser(@PathParam("username") String userName) {
  7         ...
  8     }
  9 }

If it is required that a user name must only consist of lower and upper case numeric characters then it is possible to declare a particular regular expression, which overrides the default regular expression, "[^/]+?", for example:

@Path("users/{username: [a-zA-Z][a-zA-Z_0-9]}")

In this type of example the username variable will only match user names that begin with one upper or lower case letter and zero or more alpha numeric characters and the underscore character. If a user name does not match that a 404 (Not Found) response will occur.

A @Path value may or may not begin with a '/', it makes no difference. Likewise, by default, a @Path value may or may not end in a '/', it makes no difference, and thus request URLs that end or do not end in a '/' will both be matched. However, Jersey has a redirection mechanism, which if enabled, automatically performs redirection to a request URL ending in a '/' if a request URL does not end in a '/' and the matching @Path does end in a '/'.

1.1.2. HTTP Methods

@GET, @PUT, @POST, @DELETE, and @HEAD are resource method designator annotations defined by JAX-RS and which correspond to the similarly named HTTP methods. In the example above, the annotated Java method will process HTTP GET requests. The behavior of a resource is determined by which of the HTTP methods the resource is responding to.

The following example is an extract from the storage service sample that shows the use of the PUT method to create or update a storage container:

Example 1.3. PUT method

  1 @PUT
  2 public Response putContainer() {
  3     System.out.println("PUT CONTAINER " + container);
  5     URI uri =  uriInfo.getAbsolutePath();
  6     Container c = new Container(container, uri.toString());
  8     Response r;
  9     if (!MemoryStore.MS.hasContainer(c)) {
 10         r = Response.created(uri).build();
 11     } else {
 12         r = Response.noContent().build();
 13     }
 15     MemoryStore.MS.createContainer(c);
 16     return r;
 17 }

By default the JAX-RS runtime will automatically support the methods HEAD and OPTIONS, if not explicitly implemented. For HEAD the runtime will invoke the implemented GET method (if present) and ignore the response entity (if set). For OPTIONS the the Allow response header will be set to the set of HTTP methods support by the resource. In addition Jersey will return a WADL document describing the resource.

1.1.3. @Produces

The @Produces annotation is used to specify the MIME media types of representations a resource can produce and send back to the client. In this example, the Java method will produce representations identified by the MIME media type "text/plain".

@Produces can be applied at both the class and method levels. Here's an example:

Example 1.4. Specifying output MIME type

  1 @Path("/myResource")
  2 @Produces("text/plain")
  3 public class SomeResource {
  4     @GET
  5     public String doGetAsPlainText() {
  6         ...
  7     }
  9     @GET
 10     @Produces("text/html")
 11     public String doGetAsHtml() {
 12         ...
 13     }
 14 }

The doGetAsPlainText method defaults to the MIME type of the @Produces annotation at the class level. The doGetAsHtml method's @Produces annotation overrides the class-level @Produces setting, and specifies that the method can produce HTML rather than plain text.

If a resource class is capable of producing more that one MIME media type then the resource method chosen will correspond to the most acceptable media type as declared by the client. More specifically the Accept header of the HTTP request declared what is most acceptable. For example if the Accept header is:

Accept: text/plain

then the doGetAsPlainText method will be invoked. Alternatively if the Accept header is:

Accept: text/plain;q=0.9, text/html

which declares that the client can accept media types of "text/plain" and "text/html" but prefers the latter, then the doGetAsHtml method will be invoked.

More than one media type may be declared in the same @Produces declaration, for example:

Example 1.5. Using multiple output MIME types

  1 @GET
  2 @Produces({"application/xml", "application/json"})
  3 public String doGetAsXmlOrJson() {
  4     ...
  5 }

The doGetAsXmlOrJson method will get invoked if either of the media types "application/xml" and "application/json" are acceptable. If both are equally acceptable then the former will be chosen because it occurs first.

The examples above refer explicitly to MIME media types for clarity. It is possible to refer to constant values, which may reduce typographical errors, see the constant field values of MediaType.

1.1.4. @Consumes

The @Consumes annotation is used to specify the MIME media types of representations a resource can consume that were sent by the client. The above example can be modified to set the cliched message as follows:

Example 1.6. Specifying input MIME type

  1 @POST
  2 @Consumes("text/plain")
  3 public void postClichedMessage(String message) {
  4     // Store the message
  5 }

In this example, the Java method will consume representations identified by the MIME media type "text/plain". Notice that the resource method returns void. This means no representation is returned and response with a status code of 204 (No Content) will be returned.

@Consumes can be applied at both the class and method levels and more than one media type may be declared in the same @Consumes declaration.

1.2. Deploying a RESTful Web Service

JAX-RS provides the deployment agnostic abstract class Application for declaring root resource and provider classes, and root resource and provider singleton instances. A Web service may extend this class to declare root resource and provider classes. For example,

Example 1.7. Deployment agnostic application model

  1 public class MyApplicaton extends Application {
  2     public Set<Class<?>> getClasses() {
  3         Set<Class<?>> s = new HashSet<Class<?>>();
  4         s.add(HelloWorldResource.class);
  5         return s;
  6     }
  7 }

Alternatively it is possible to reuse one of Jersey's implementations that scans for root resource and provider classes given a classpath or a set of package names. Such classes are automatically added to the set of classes that are returned by getClasses. For example, the following scans for root resource and provider classes in packages "", "" and in any sub-packages of those two:

Example 1.8. Reusing Jersey implementation in your custom application model

  1 public class MyApplication extends PackagesResourceConfig {
  2     public MyApplication() {
  3         super(";");
  4     }
  5 }

For servlet deployments JAX-RS specifies that a class that implements Application may be declared instead of a servlet class in <servlet-class> element of a web.xml, but as of writing this is not currently supported for Jersey. Instead it is necessary to declare the Jersey specific servlet and the Application class as follows:

Example 1.9. Deployment of your application using Jersey specific servlet

  1 <web-app>
  2     <servlet>
  3         <servlet-name>Jersey Web Application</servlet-name>
  4         <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
  5         <init-param>
  6             <param-name></param-name>
  7             <param-value>MyApplication</param-value>
  8         </init-param>
  9     </servlet>
 10     ....

Alternatively a simpler approach is to let Jersey choose the PackagesResourceConfig implementation automatically by declaring the packages as follows:

Example 1.10. Using Jersey specific servlet without an application model instance

  1 <web-app>
  2     <servlet>
  3         <servlet-name>Jersey Web Application</servlet-name>
  4         <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
  5         <init-param>
  6             <param-name></param-name>
  7             <param-value>;</param-value>
  8         </init-param>
  9     </servlet>
 10     ....

JAX-RS also provides the ability to obtain a container specific artifact from an Application instance. For example, Jersey supports using Grizzly as follows:

SelectorThread st = RuntimeDelegate.createEndpoint(new MyApplication(), SelectorThread.class);

Jersey also provides Grizzly helper classes to deploy the ServletThread instance at a base URL for in-process deployment.

The Jersey samples provide many examples of Servlet-based and Grizzly-in-process-based deployments.

1.3. Extracting Request Parameters

Parameters of a resource method may be annotated with parameter-based annotations to extract information from a request. A previous example presented the use @PathParam to extract a path parameter from the path component of the request URL that matched the path declared in @Path.

@QueryParam is used to extract query parameters from the Query component of the request URL. The following example is an extract from the sparklines sample:

Example 1.11. Query parameters

  1 @Path("smooth")
  2 @GET
  3 public Response smooth(
  4         @DefaultValue("2") @QueryParam("step") int step,
  5         @DefaultValue("true") @QueryParam("min-m") boolean hasMin,
  6         @DefaultValue("true") @QueryParam("max-m") boolean hasMax,
  7         @DefaultValue("true") @QueryParam("last-m") boolean hasLast,           
  8         @DefaultValue("blue") @QueryParam("min-color") ColorParam minColor,
  9         @DefaultValue("green") @QueryParam("max-color") ColorParam maxColor,
 10         @DefaultValue("red") @QueryParam("last-color") ColorParam lastColor
 11         ) { ... }

If a query parameter "step" exists in the query component of the request URI then the "step" value will be will extracted and parsed as a 32 bit signed integer and assigned to the step method parameter. If "step" does not exist then a default value of 2, as declared in the @DefaultValue annotation, will be assigned to the step method parameter. If the "step" value cannot be parsed as an 32 bit signed integer then a 400 (Client Error) response is returned. User defined Java types such as ColorParam may be used, which as implemented as follows:

Example 1.12. Custom Java type for consuming request parameters

  1 public class ColorParam extends Color {
  2     public ColorParam(String s) {
  3         super(getRGB(s));
  4     }
  6     private static int getRGB(String s) {
  7         if (s.charAt(0) == '#') {
  8             try {
  9                 Color c = Color.decode("0x" + s.substring(1));
 10                 return c.getRGB();
 11             } catch (NumberFormatException e) {
 12                 throw new WebApplicationException(400);
 13             }
 14         } else {
 15             try {
 16                 Field f = Color.class.getField(s);
 17                 return ((Color)f.get(null)).getRGB();
 18             } catch (Exception e) {
 19                 throw new WebApplicationException(400);
 20             }
 21         }
 22     }
 23 }

In general the Java type of the method parameter may:

  1. Be a primitive type;

  2. Have a constructor that accepts a single String argument;

  3. Have a static method named valueOf that accepts a single String argument (see, for example, Integer.valueOf(String)); or

  4. Be List<T>, Set<T> or SortedSet<T>, where T satisfies 2 or 3 above. The resulting collection is read-only.

Sometimes parameters may contain more than one value for the same name. If this is the case then types in 4) may be used to obtain all values.

If the @DefaultValue is not used on conjuction with @QueryParam and the query parameter is not present in the request then value will be an empty collection for List, Set or SortedSet, null for other object types, and the Java-defined default for primitive types.

The @PathParam and the other parameter-based annotations, @MatrixParam, @HeaderParam, @CookieParam and @FormParam obey the same rules as @QueryParam. @MatrixParam extracts information from URL path segments. @HeaderParam extracts information from the HTTP headers. @CookieParam extracts information from the cookies declared in cookie related HTTP headers.

@FormParam is slightly special because it extracts information from a request representation that is of the MIME media type "application/x-www-form-urlencoded" and conforms to the encoding specified by HTML forms, as described here. This parameter is very useful for extracting information that is POSTed by HTML forms, for example the following extracts the form parameter named "name" from the POSTed form data:

Example 1.13. Processing POSTed HTML form

  1 @POST
  2 @Consumes("application/x-www-form-urlencoded")
  3 public void post(@FormParam("name") String name) {
  4     // Store the message
  5 }

If it is necessary to obtain a general map of parameter name to values then, for query and path parameters it is possible to do the following:

Example 1.14. Obtaining general map of URI path and/or query parameters

  1 @GET
  2 public String get(@Context UriInfo ui) {
  3     MultivaluedMap<String, String> queryParams = ui.getQueryParameters();
  4     MultivaluedMap<String, String> pathParams = ui.getPathParameters();
  5 }

For header and cookie parameters the following:

Example 1.15. Obtaining general map of header parameters

  1 @GET
  2 public String get(@Context HttpHeaders hh) {
  3     MultivaluedMap<String, String> headerParams = ui.getRequestHeaders();
  4     Map<String, Cookie> pathParams = ui.getCookies();
  5 }

In general @Context can be used to obtain contextual Java types related to the request or response. For form parameters it is possible to do the following:

Example 1.16. Obtaining general map of form parameters

  1 @POST
  2 @Consumes("application/x-www-form-urlencoded")
  3 public void post(MultivaluedMap<String, String> formParams) {
  4     // Store the message
  5 }

1.4. Represetations and Java Types

Previous sections on @Produces and @Consumes referred to MIME media types of representations and showed resource methods that consume and produce the Java type String for a number of different media types. However, String is just one of many Java types that are required to be supported by JAX-RS implementations.

Java types such as byte[],, and are supported. In addition JAXB beans are supported. Such beans are JAXBElement or classes annotated with @XmlRootElement or @XmlType. The samples jaxb and json-from-jaxb show the use of JAXB beans.

Unlike method parameters that are associated with the extraction of request parameters, the method parameter associated with the representation being consumed does not require annotating. A maximum of one such unannotated method parameter may exist since there may only be a maximum of one such representation sent in a request.

The representation being produced corresponds to what is returned by the resource method. For example JAX-RS makes it simple to produce images that are instance of File as follows:

Example 1.17. Using File with a specific MIME type to produce a response

  1 @GET
  2 @Path("/images/{image}")
  3 @Produces("image/*")
  4 public Response getImage(@PathParam("image") String image) {
  5     File f = new File(image);
  7     if (!f.exists()) {
  8         throw new WebApplicationException(404);
  9     }
 11     String mt = new MimetypesFileTypeMap().getContentType(f);
 12     return Response.ok(f, mt).build();
 13 }

A File type can also be used when consuming, a temporary file will be created where the request entity is stored.

The Content-Type (if not set, see next section) can be automatically set from the MIME media types declared by @Produces if the most acceptable media type is not a wild card (one that contains a *, for example "application/" or "/*"). Given the following method:

Example 1.18. The most acceptable MIME type is used when multiple output MIME types allowed

  1 @GET
  2 @Produces({"application/xml", "application/json"})
  3 public String doGetAsXmlOrJson() {
  4     ...
  5 }

if "application/xml" is the most acceptable then the Content-Type of the response will be set to "application/xml".

1.5. Building Responses

Sometimes it is necessary to return additional information in response to a HTTP request. Such information may be built and returned using Response and Response.ResponseBuilder. For example, a common RESTful pattern for the creation of a new resource is to support a POST request that returns a 201 (Created) status code and a Location header whose value is the URI to the newly created resource. This may be acheived as follows:

Example 1.19. Returning 201 status code and adding Location header in response to POST request

  1 @POST
  2 @Consumes("application/xml")
  3 public Response post(String content) {
  4     URI createdUri = ...
  5     create(content);
  6     return Response.created(createdUri).build();
  7 }

In the above no representation produced is returned, this can be achieved by building an entity as part of the response as follows:

Example 1.20. Adding an entity body to a custom response

  1 @POST
  2 @Consumes("application/xml")
  3 public Response post(String content) {
  4     URI createdUri = ...
  5     String createdContent = create(content);
  6     return Response.created(createdUri).entity(createdContent).build();
  7 }

Response building provides other functionality such as setting the entity tag and last modified date of the representation.

1.6. Sub-resources

@Path may be used on classes and such classes are referred to as root resource classes. @Path may also be used on methods of root resource classes. This enables common functionality for a number of resources to be grouped together and potentially reused.

The first way @Path may be used is on resource methods and such methods are referred to as sub-resource methods. The following example shows the method signatures for a root resource class from the jmaki-backend sample:

Example 1.21. Sub-resource methods

  1 @Singleton
  2 @Path("/printers")
  3 public class PrintersResource {
  5     @GET
  6     @Produces({"application/json", "application/xml"})
  7     public WebResourceList getMyResources() { ... }
  9     @GET @Path("/list")
 10     @Produces({"application/json", "application/xml"})
 11     public WebResourceList getListOfPrinters() { ... }
 13     @GET @Path("/jMakiTable")
 14     @Produces("application/json")
 15     public PrinterTableModel getTable() { ... }
 17     @GET @Path("/jMakiTree")
 18     @Produces("application/json")
 19     public TreeModel getTree() { ... }
 21     @GET @Path("/ids/{printerid}")
 22     @Produces({"application/json", "application/xml"})
 23     public Printer getPrinter(@PathParam("printerid") String printerId) { ... }
 25     @PUT @Path("/ids/{printerid}")
 26     @Consumes({"application/json", "application/xml"})
 27     public void putPrinter(@PathParam("printerid") String printerId,  Printer printer) { ... }
 29     @DELETE @Path("/ids/{printerid}")
 30     public void deletePrinter(@PathParam("printerid") String printerId) { ... }
 31 }

If the path of the request URL is "printers" then the resource methods not annotated with @Path will be selected. If the request path of the request URL is "printers/list" then first the root resource class will be matched and then the sub-resource methods that match "list" will be selected, which in this case is the sub-resource method getListOfPrinters. So in this example hierarchical matching on the path of the request URL is performed.

The second way @Path may be used is on methods not annotated with resource method designators such as @GET or @POST. Such methods are referred to as sub-resource locators. The following example shows the method signatures for a root resource class and a resource class from the optimistic-concurrency sample:

Example 1.22. Sub-resource locators

  1 @Path("/item")
  2 public class ItemResource {
  3     @Context UriInfo uriInfo;
  5     @Path("content")
  6     public ItemContentResource getItemContentResource() {
  7         return new ItemContentResource();
  8     }
 10     @GET
 11     @Produces("application/xml")
 12     public Item get() { ... }
 13 }
 15 public class ItemContentResource {
 17     @GET
 18     public Response get() { ... }
 20     @PUT
 21     @Path("{version}")
 22     public void put(
 23             @PathParam("version") int version,
 24             @Context HttpHeaders headers,
 25             byte[] in) { ... }
 26 }

The root resource class ItemResource contains the sub-resource locator method getItemContentResource that returns a new resource class. If the path of the request URL is "item/content" then first of all the root resource will be matched, then the sub-resource locator will be matched and invoked, which returns an instance of the ItemContentResource resource class. Sub-resource locators enable reuse of resource classes.

In addition the processing of resource classes returned by sub-resource locators is performed at runtime thus it is possible to support polymorphism. A sub-resource locator may return different sub-types depending on the request (for example a sub-resource locator could return different sub-types dependent on the role of the principle that is authenticated).

Note that the runtime will not manage the life-cycle or perform any field injection onto instances returned from sub-resource locator methods. This is because the runtime does not know what the life-cycle of the instance is.

1.7. Building URIs

A very important aspects of REST is hyperlinks, URIs, in representations that clients can use to transition the Web service to new application states (this is otherwise known as "hypermedia as the engine of application state"). HTML forms present a good example of this in practice.

Building URIs and building them safely is not easy with, which is why JAX-RS has the UriBuilder class that makes it simple and easy to build URIs safely.

UriBuilder can be used to build new URIs or build from existing URIs. For resource classes it is more than likely that URIs will be built from the base URI the Web service is deployed at or from the request URI. The class UriInfo provides such information (in addition to further information, see next section).

The following example shows URI building with UriInfo and UriBuilder from the bookmark sample:

Example 1.23. URI building

  1 @Path("/users/")
  2 public class UsersResource {
  4     @Context UriInfo uriInfo;
  6     ...
  8     @GET
  9     @Produces("application/json")
 10     public JSONArray getUsersAsJsonArray() {
 11         JSONArray uriArray = new JSONArray();
 12         for (UserEntity userEntity : getUsers()) {
 13             UriBuilder ub = uriInfo.getAbsolutePathBuilder();
 14             URI userUri = ub.
 15                     path(userEntity.getUserid()).
 16                     build();
 17             uriArray.put(userUri.toASCIIString());
 18         }
 19         return uriArray;
 20     }
 21 }

UriInfo is obtained using the @Context annotation, and in this particular example injection onto the field of the root resource class is performed, previous examples showed the use of @Context on resource method parameters.

UriInfo can be used to obtain URIs and associated UriBuilder instances for the following URIs: the base URI the application is deployed at; the request URI; and the absolute path URI, which is the request URI minus any query components.

The getUsersAsJsonArray method constructs a JSONArrray where each element is a URI identifying a specific user resource. The URI is built from the absolute path of the request URI by calling uriInfo.getAbsolutePathBuilder(). A new path segment is added, which is the user ID, and then the URI is built. Notice that it is not necessary to worry about the inclusion of '/' characters or that the user ID may contain characters that need to be percent encoded. UriBuilder takes care of such details.

UriBuilder can be used to build/replace query or matrix parameters. URI templates can also be declared, for example the following will build the URI "http://localhost/segment?name=value":

Example 1.24. Building URIs using query parameters

  1 UriBuilder.fromUri("http://localhost/").
  2     path("{a}").
  3     queryParam("name", "{value}").
  4     build("segment", "value");

1.8. WebApplicationException and Mapping Exceptions to Responses

Previous sections have shown how to return HTTP responses and it is possible to return HTTP errors using the same mechanism. However, sometimes when programming in Java it is more natural to use exceptions for HTTP errors.

The following example shows the throwing of a NotFoundException from the bookmark sample:

Example 1.25. Throwing Jersey specific exceptions to control response

  1 @Path("items/{itemid}/")
  2 public Item getItem(@PathParam("itemid") String itemid) {
  3     Item i = getItems().get(itemid);
  4     if (i == null)
  5         throw new NotFoundException("Item, " + itemid + ", is not found");
  7     return i;
  8 }

This exception is a Jersey specific exception that extends WebApplicationException and builds a HTTP response with the 404 status code and an optional message as the body of the response:

Example 1.26. Jersey specific exception implementation

  1 public class NotFoundException extends WebApplicationException {
  3     /**
  4      * Create a HTTP 404 (Not Found) exception.
  5      */
  6     public NotFoundException() {
  7         super(Responses.notFound().build());
  8     }
 10     /**
 11      * Create a HTTP 404 (Not Found) exception.
 12      * @param message the String that is the entity of the 404 response.
 13      */
 14     public NotFoundException(String message) {
 15         super(Response.status(Responses.NOT_FOUND).
 16                 entity(message).type("text/plain").build());
 17     }
 19 }

In other cases it may not be appropriate to throw instances of WebApplicationException, or classes that extend WebApplicationException, and instead it may be preferable to map an existing exception to a response. For such cases it is possible to use the ExceptionMapper interface. For example, the following maps the EntityNotFoundException to a 404 (Not Found) response:

Example 1.27. Mapping generic exceptions to responses

  1 @Provider
  2 public class EntityNotFoundMapper implements
  3         ExceptionMapper<javax.persistence.EntityNotFoundException> {
  4     public Response toResponse(javax.persistence.EntityNotFoundException ex) {
  5         return Response.status(404).
  6             entity(ex.getMessage()).
  7             type("text/plain").
  8             build();
  9     }
 10 }

The above class is annotated with @Provider, this declares that the class is of interest to the JAX-RS runtime. Such a class may be added to the set of classes of the Application instance that is configured. When an application throws an EntityNotFoundException the toResponse method of the EntityNotFoundMapper instance will be invoked.

1.9. Conditional GETs and Returning 304 (Not Modified) Responses

Conditional GETs are a great way to reduce bandwidth, and potentially server-side peformance, depending on how the information used to determine conditions is calculated. A well-designed web site may return 304 (Not Modified) responses for the many of the static images it serves.

JAX-RS provides support for conditional GETs using the contextual interface Request.

The following example shows conditional GET support from the sparklines sample:

Example 1.28. Conditional GET support

  1 public SparklinesResource(
  2         @QueryParam("d") IntegerList data,
  3         @DefaultValue("0,100") @QueryParam("limits") Interval limits,
  4         @Context Request request,
  5         @Context UriInfo ui) {
  6     if (data == null)
  7         throw new WebApplicationException(400);
  9 = data;
 11     this.limits = limits;
 13     if (!limits.contains(data))
 14         throw new WebApplicationException(400);
 16     this.tag = computeEntityTag(ui.getRequestUri());
 17     if (request.getMethod().equals("GET")) {
 18         Response.ResponseBuilder rb = request.evaluatePreconditions(tag);
 19         if (rb != null)
 20             throw new WebApplicationException(;
 21     }
 22 }

The constructor of the SparklinesResouce root resource class computes an entity tag from the request URI and then calls the request.evaluatePreconditions with that entity tag. If a client request contains an If-None-Match header with a value that contains the same entity tag that was calculated then the evaluatePreconditions returns a pre-filled out response, with the 304 status code and entity tag set, that may be built and returned. Otherwise, evaluatePreconditions returns null and the normal response can be returned.

Notice that in this example the constructor of a resource class can be used perform actions that may otherwise have to be duplicated to invoked for each resource method.

1.10. Life-cycle of Root Resource Classes

By default the life-cycle of root resource classes is per-request, namely that a new instance of a root resource class is created every time the request URI path matches the root resource. This makes for a very natural programming model where constructors and fields can be utilized (as in the previous section showing the constructor of the SparklinesResource class) without concern for multiple concurrent requests to the same resource.

In general this is unlikely to be a cause of performance issues. Class construction and garbage collection of JVMs has vastly improved over the years and many objects will be created and discarded to serve and process the HTTP request and return the HTTP response.

Instances of singleton root resource classes can be declared by an instance of Application.

Jersey supports two further life-cycles using Jersey specific annotations. If a root resource class is annotated with @Singleton then only one instance is created per-web applcation. If a root resource class is annotated with @PerSession then one instance is created per web session and stored as a session attribute.

1.11. Security

Security information is available by obtaining the SecurityContext using @Context, which is essentially the equivalent functionality available on the HttpServletRequest.

SecurityContext can be used in conjunction with sub-resource locators to return different resources if the user principle is included in a certain role. For example, a sub-resource locator could return a different resource if a user is a preferred customer:

Example 1.29. Accessing SecurityContext

  1 @Path("basket")
  2 public ShoppingBasketResource get(@Context SecurityContext sc) {
  3     if (sc.isUserInRole("PreferredCustomer") {
  4        return new PreferredCustomerShoppingBaskestResource();
  5     } else {
  6        return new ShoppingBasketResource();
  7     }
  8 }

1.12. Rules of Injection

Previous sections have presented examples of annotated types, mostly annotated method parameters but also annotated fields of a class, for the injection of values onto those types.

This section presents the rules of injection of values on annotated types. Injection can be performed on fields, constructor parameters, resource/sub-resource/sub-resource locator method parameters and bean setter methods. The following presents an example of all such injection cases:

Example 1.30. Injection

  1 @Path("id: \d+")
  2 public class InjectedResource {
  3     // Injection onto field
  4     @DefaultValue("q") @QueryParam("p")
  5     private String p;
  7     // Injection onto constructor parameter
  8     public InjectedResource(@PathParam("id") int id) { ... }
 10     // Injection onto resource method parameter
 11     @GET
 12     public String get(@Context UriInfo ui) { ... }
 14     // Injection onto sub-resource resource method parameter
 15     @Path("sub-id")
 16     @GET
 17     public String get(@PathParam("sub-id") String id) { ... }
 19     // Injection onto sub-resource locator method parameter
 20     @Path("sub-id")
 21     public SubResource getSubResource(@PathParam("sub-id") String id) { ... }
 23     // Injection using bean setter method
 24     @HeaderParam("X-header")
 25     public void setHeader(String header) { ... }
 26 }

There are some restrictions when injecting on to resource classes with a life-cycle other than per-request. In such cases it is not possible to injected onto fields for the annotations associated with extraction of request parameters. However, it is possible to use the @Context annotation on fields, in such cases a thread local proxy will be injected.

The @FormParam annotation is special and may only be utilized on resource and sub-resource methods. This is because it extracts information from a request entity.

1.13. Use of @Context

Previous sections have introduced the use of @Context. Chapter 5 of the JAX-RS specification presents all the standard JAX-RS Java types that may be used with @Context.

When deploying a JAX-RS application using servlet then ServletConfig, ServletContext, HttpServletRequest and HttpServletResponse are available using @Context.

1.14. Annotations Defined By JAX-RS

For a list of the annotations specified by JAX-RS see Appendix A of the specification.

Chapter 2. JSON Support

Jersey JSON support comes as a set of JAX-RS MessageBodyReader and MessageBodyWriter providers distributed with jersey-json module. These providers enable using two basic approaches when working with JSON format:

Both approaches use the same principle. You need to make your resource methods consume and/or produce instances of certain Java types, known to provided MessageBodyReaders/Writers. Also, naturally, you need to make sure you use jersey-json module with your application.

2.1. JAXB Based JSON support

Taking this approach will save you a lot of time, if you want to easily produce/consume both JSON and XML data format. Because even then you will still be able to use a unified Java model. Another advantage is simplicity of working with such a model, as JAXB leverages annotated POJOs and these could be handled as simple Java beans

A disadvantage of JAXB based approach could be if you need to work with a very specific JSON format. Then it could be difficult to find a proper way to get such a format produced and consumed. This is a reason why a lot of configuration options are provided, so that you can control how things get serialized out and deserialized back.

Following is a very simple example of how a JAXB bean could look like.

Example 2.1. Simple JAXB bean implementation

  1 @XmlRootElement
  2 public class MyJaxbBean {
  3   public String name;
  4   public int age;
  6   public MyJaxbBean() {} // JAXB needs this
  8   public MyJaxbBean(String name, int age) {
  9 = name;
 10     this.age = age;
 11   }
 12 }

Using the above JAXB bean for producing JSON data format from you resource method, is then as simple as:

Example 2.2. JAXB bean used to generate JSON representation

  1 @GET @Produces("application/json")
  2 public MyJaxbBean getMyBean() {
  3    return new MyJaxbBean("Agamemnon", 32);
  4 }

Notice, that JSON specific mime type is specified in @Produces annotation, and the method returns an instance of MyJaxbBean, which JAXB is able to process. Resulting JSON in this case would look like:

    {"name":"Agamemnon", "age":"32"}

2.1.1. Configuration Options

JAXB itself enables you to control output JSON format to certain extent. Specifically renaming and ommiting items is easy to do directly using JAXB annotations. E.g. the following example depicts changes in the above mentioned MyJaxbBean that will result in {"king":"Agamemnon"} JSON output.

Example 2.3. Tweaking JSON format using JAXB

  1 @XmlRootElement
  2 public class MyJaxbBean {
  4     @XmlElement(name="king")
  5     public String name;
  7     @XmlTransient
  8     public int age;
 10     // several lines removed       
 11 }

To achieve more important JSON format changes, you will need to configure Jersey JSON procesor itself. Various configuration options could be set on an JSONConfiguration instance. The instance could be then further used to create a JSONConfigurated JSONJAXBContext, which serves as a main configuration point in this area. To pass your specialized JSONJAXBContext to Jersey, you will finally need to implement a JAXBContext ContextResolver

Example 2.4. An example of a JAXBContext resolver implementation

  1 @Provider
  2 public class JAXBContextResolver implements ContextResolver<JAXBContext> {
  4     private JAXBContext context;
  5     private Class[] types = {MyJaxbBean.class};
  7     public JAXBContextResolver() throws Exception {
  8         this.context = 
  9 	  new JSONJAXBContext( (1)
 10 	    JSONConfiguration.natural().build(), types); (2)
 11     }
 13     public JAXBContext getContext(Class<?> objectType) {
 14         for (Class type : types) {
 15             if (type == objectType) {
 16                 return context;
 17             }
 18         }
 19         return null;
 20     }
 21 }


Creation of our specialized JAXBContext


Final JSON format is given by this JSONConfiguration instance

2.1.2. JSON Notations

JSONConfiguration allows you to use four various JSON notations. Each of these notations serializes JSON in a different way. Following is a list of supported notations:

  • MAPPED (default notation)




Individual notations and their further configuration options are described bellow. Rather then explaining rules for mapping XML constructs into JSON, the notations will be described using a simple example. Following are JAXB beans, which will be used.

Example 2.5. JAXB beans for JSON supported notations description, simple address bean

  1 @XmlRootElement
  2 public class Address {
  3     public String street;
  4     public String town;
  6     public Address(){}
  8     public Address(String street, String town) {
  9         this.street = street;
 10 = town;
 11     }
 12 }

Example 2.6. JAXB beans for JSON supported notations description, contact bean

  1 @XmlRootElement
  2 public class Contact {
  4     public int id;
  5     public String name;
  6     public List<Address> addresses;
  8     public Contact() {};
 10     public Contact(int id, String name, List<Address> addresses) {
 11 = name;
 12 = id;
 13         this.addresses = 
 14 	        (addresses != null) ? new LinkedList<Address>(addresses) : null;
 15     }
 16 }

Following text will be mainly working with a contact bean initialized with:

Example 2.7. JAXB beans for JSON supported notations description, initialization

final Address[] addresses = {new Address("Long Street 1", "Short Village")};
Contact contact = new Contact(2, "Bob", Arrays.asList(addresses));

I.e. contact bean with id=2, name="Bob" containing a single address (street="Long Street 1", town="Short Village").

All bellow described configuration options are documented also in apidocs at Mapped notation

JSONConfiguration based on mapped notation could be build with


for usage in a JAXBContext resolver, Example 2.4, “An example of a JAXBContext resolver implementation”. Then a contact bean initialized with Example 2.7, “JAXB beans for JSON supported notations description, initialization”, will be serialized as

Example 2.8. JSON expression produced using mapped notation

  1 { "id":"2" 
  2  ,"name":"Bob"
  3  ,"addresses":{"street":"Long Street 1"
  4                     ,"town":"Short Village"}}

The JSON representation seems fine, and will be working flawlessly with Java based Jersey client API.

However, at least one issue might appear once you start using it with a JavaScript based client. The information, that addresses item represents an array, is being lost for every single element array. If you added another address bean to the contact,

contact.addresses.add(new Address("Short Street 1000", "Long Village"));

, you would get

  1 { "id":"2" 
  2  ,"name":"Bob"
  3  ,"addresses":[{"street":"Long Street 1","town":"Short Village"}
  4               ,{"street":"Short Street 1000","town":"Long Village"}]}

Both representations are correct, but you will not be able to consume them using a single JavaScript client, because to access "Short Village" value, you will write in one case and addresses[0].town in the other. To fix this issue, you need to instruct the JSON processor, what items need to be treated as arrays by setting an optional property, arrays, on your JSONConfiguration object. For our case, you would do it with

Example 2.9. Force arrays in mapped JSON notation


You can use multiple string values in the arrays method call, in case you are dealing with more than one array item in your beans. Similar mechanism (one or more argument values) applies also for all below desribed options.

Another issue might be, that number value, 2, for id item gets written as a string, "2". To avoid this, you can use another optional property on JSONConfiguration called nonStrings.

Example 2.10. Force non-string values in mapped JSON notation


It might happen you use XML attributes in your JAXB beans. In mapped JSON notation, these attribute names are prefixed with @ character. If id was an attribute, it´s definition would look like:

  public int id;

and then you would get

{"@id":"2" ...

at the JSON output. In case, you want to get rid of the @ prefix, you can take advantage of another configuration option of JSONConfiguration, called attributeAsElement. Usage is similar to previous options.

Example 2.11. XML attributes as XML elements in mapped JSON notation


Mapped JSON notation was designed to produce the simplest possible JSON expression out of JAXB beans. While in XML, you must always have a root tag to start a XML document with, there is no such a constraint in JSON. If you wanted to be strict, you might have wanted to keep a XML root tag equivalent generated in your JSON. If that is the case, another configuration option is available for you, which is called rootUnwrapping. You can use it as follows:

Example 2.12. Keep XML root tag equivalent in JSON mapped JSON notation


and get the following JSON for our Contact bean:

Example 2.13. XML root tag equivalent kept in JSON using mapped notation

  1 {"contact":{ "id":"2" 
  2  ,"name":"Bob"
  3  ,"addresses":{"street":"Long Street 1"
  4                     ,"town":"Short Village"}}}

rootUnwrapping option is set to true by default. You should switch it to false if you use inheritance at your JAXB beans. Then JAXB might try to encode type information into root element names, and by stripping these elements off, you could break unmarshalling.

In version 1.1.1-ea, XML namespace support was added to the MAPPED JSON notation. There is of course no such thing as XML namespaces in JSON, but when working from JAXB, XML infoset is used as an intermediary format. And then when various XML namespaces are used, ceratin information related to the concrete namespaces is needed even in JSON data, so that the JSON procesor could correctly unmarshal JSON to XML and JAXB. To make it short, the XML namespace support means, you should be able to use the very same JAXB beans for XML and JSON even if XML namespaces are involved.

Namespace mapping definition is similar to Example 2.18, “XML namespace to JSON mapping configuration for Jettison based mapped notation”

Example 2.14. XML namespace to JSON mapping configuration for mapped notation

  1         Map<String,String> ns2json = new HashMap<String, String>();
  2         ns2json.put("", "example");
  3         context = new JSONJAXBContext(
  4 	      JSONConfiguration.mapped()
  5 	           .xml2JsonNs(ns2json).build(), types); Natural notation

After using mapped JSON notation for a while, it was apparent, that a need to configure all the various things manually could be a bit problematic. To avoid the manual work, a new, natural, JSON notation was introduced in Jersey version 1.0.2. With natural notation, Jersey will automatically figure out how individual items need to be processed, so that you do not need to do any kind of manual configuration. Java arrays and lists are mapped into JSON arrays, even for single-element cases. Java numbers and booleans are correctly mapped into JSON numbers and booleans, and you do not need to bother with XML attributes, as in JSON, they keep the original names. So without any additional configuration, just using


for configuring your JAXBContext, you will get the following JSON for the bean initialized at Example 2.7, “JAXB beans for JSON supported notations description, initialization”:

Example 2.15. JSON expression produced using natural notation

  1 { "id":2
  2  ,"name":"Bob"
  3  ,"addresses":[{"street":"Long Street 1"
  4                      ,"town":"Short Village"}]}

You might notice, that the single element array addresses remains an array, and also the non-string id value is not limited with double quotes, as natural notation automatically detects these things.

To support cases, when you use inheritance for your JAXB beans, an option was introduced to the natural JSON configuration builder to forbid XML root element stripping. The option looks pretty same as at the default mapped notation case (Example 2.12, “Keep XML root tag equivalent in JSON mapped JSON notation”).

Example 2.16. Keep XML root tag equivalent in JSON natural JSON notation

JSONConfiguration.natural().rootUnwrapping(false).build() Jettison mapped notation

Next two notations are based on project Jettison. You might want to use one of these notations, when working with more complex XML documents. Namely when you deal with multiple XML namespaces in your JAXB beans.

Jettison based mapped notation could be configured using:


If nothing else is configured, you will get similar JSON output as for the default, mapped, notation:

Example 2.17. JSON expression produced using Jettison based mapped notation

  1 { "contact:{"id":2
  2               ,"name":"Bob"
  3               ,"addresses":{"street":"Long Street 1"
  4                                  ,"town":"Short Village"}}

The only difference is, your numbers and booleans will not be converted into strings, but you have no option for forcing arrays remain arrays in single-element case. Also the JSON object, representing XML root tag is being produced.

If you need to deal with various XML namespaces, however, you will find Jettison mapped notation pretty useful. Lets define a particular namespace for id item:

  public int id;

Then you simply confgure a mapping from XML namespace into JSON prefix as follows:

Example 2.18. XML namespace to JSON mapping configuration for Jettison based mapped notation

  1         Map<String,String> ns2json = new HashMap<String, String>();
  2         ns2json.put("", "example");
  3         context = new JSONJAXBContext(
  4 	      JSONConfiguration.mappedJettison()
  5 	           .xml2JsonNs(ns2json).build(), types);

Resulting JSON will look like in the example bellow.

Example 2.19. JSON expression with XML namespaces mapped into JSON

  1 { "contact:{"":2
  2               ,"name":"Bob"
  3               ,"addresses":{"street":"Long Street 1"
  4                                  ,"town":"Short Village"}}

Please note, that id item became based on the XML namespace mapping. If you have more XML namespaces in your XML, you will need to configure appropriate mapping for all of them Badgerfish notation

Badgerfish notation is the other notation based on Jettison. From JSON and JavaScript perspective, this notation is definitely the worst readable one. You will probably not want to use it, unless you need to make sure your JAXB beans could be flawlessly written and read back to and from JSON, without bothering with any formatting configuration, namespaces, etc.

JSONConfiguration instance using badgerfish notation could be built with


and the output JSON for Example 2.7, “JAXB beans for JSON supported notations description, initialization” will be as follows.

Example 2.20. JSON expression produced using badgerfish notation

  1 {"contact":{"id":{"$":"2"}
  2               ,"name":{"$":"Bob"}
  3               ,"addresses":{"street":{"$":"Long Street 1"}
  4                                  ,"town":{"$":"Short Village"}}}}

2.2. Low-Level JSON support

Using this approach means you will be using JSONObject and/or JSONArray classes for your data representations. These classes are actually taken from Jettison project, but conform to the description provided at

The biggest advantage here is, that you will gain full control over the JSON format produced and consumed. On the other hand, dealing with your data model objects will probably be a bit more complex, than when taking the JAXB based approach. Differencies are depicted at the following code snipets.

Example 2.21. JAXB bean creation

MyJaxbBean myBean = new MyJaxbBean("Agamemnon", 32);

Above you construct a simple JAXB bean, which could be written in JSON as {"name":"Agamemnon", "age":32}

Now to build an equivalent JSONObject (in terms of resulting JSON expression), you would need several more lines of code.

Example 2.22. Constructing a JSONObject

  1 JSONObject myObject = new JSONObject();
  2 myObject.JSONObject myObject = new JSONObject();
  3 try {
  4   myObject.put("name", "Agamemnon");
  5   myObject.put("age", 32);
  6 } catch (JSONException ex) {
  7   LOGGER.log(Level.SEVERE, "Error ...", ex);
  8 }

2.2.1. Examples

Download to get a more complex example using low-level JSON support.