JAX-RS. Sam Guinea

Transcription

1 JAX-RS Sam Guinea

2 JAX-RS Java API that provides support in creating services according to the REST architectural style. JAX-RS uses annotations to simplify the development of: resources clients. Implementations: Apache CXF Jersey: reference implementation from Oracle and integrated in GlassFish RESTEasy, Jboss s implementation.

3 @Path Specifies the URI Path of the resource corresponding to a class Variables can be embedded in the URI, and then retrieved with annotation.

4 may be used on classes and such classes are referred to as root resource may also be used on methods of root resource classes.

5 are resource method designator annotations. Correspond to the HTTP methods.

6 @Produces Specifies the MIME media types of representations a resource can produce. Multiple representations of the same resource are allowed. Client

7 @Consumes It is used to specify the MIME media types of representations a resource can consume. It can be applied at both the class and method levels.

8 Building Responses Sometimes it is necessary to return additional information in response to a HTTP request. Such information may be built using Response. Example: adding the Location in response to a newly created resource.

9 Building URIs Useful to satisfy the principle of HATEOAS (hypermedia as the engine of application state).

10 public class InjectedResource { // Injection private String p; // Injection onto constructor parameter public InjectedResource(@PathParam("id") int id) {... } // Injection onto resource method public String get(@context UriInfo ui) {... } // Injection onto sub-resource resource public String get(@pathparam("sub-id") String id) {... } // Injection onto sub-resource locator method public SubResource getsubresource(@pathparam("sub-id") String id) {... } } // Injection using bean setter public void setheader(string header) {... }

11 Injections

12 @Context Injections This annotation is used to inject information into a class field, bean property or method parameter. Some Important Injections: UriInfo UriInfo provides static and dynamic, per-request information, about the components of a public String listqueryparamnames(@context UriInfo info) { StringBuilder buf= new StringBuilder(); for (String param: info.getqueryparameters().keyset()) { buf.append(param); buf.append("\n"); }

13 @Context Injections Headers HttpHeaders provides access to request header information either in map form or via strongly typed convenience public String listheadernames(@context HttpHeaders headers) { StringBuilder buf = new StringBuilder(); for (String header: headers.getrequestheaders().keyset()) { buf.append(header); buf.append("\n");

14 @Context Injections Request JAX-RS simplifies support for content negotiation and preconditions using the Request interface The methods of Request allow a caller to determine the best matching representation variant and to evaluate whether the current state of the resource matches any preconditions in the request. Precondition support methods return a ResponseBuilder that can be returned to the client to inform it that the request preconditions were not public Response updatefoo(@context Request request, Foo foo) { EntityTag tag = getcurrenttag(); ResponseBuilder responsebuilder = request.evaluatepreconditions(tag); if (responsebuilder!= null) return responsebuilder.build(); else return doupdate(foo); }

15 Exceptions and HTTP Responses You can use exceptions that extend WebApplicationException and build a HTTP response with the 404 status

16 SENDING BINARY DATA

17 Option 1: Base 64 POST: /api/projects/234/reports { author: 'xxxx', abstract: 'xxxx', filename: 'xxxx', filesize: 222, content: '<base64 encoded binary data>' }

18 Option 2: Multi-part Form Post POST: /api/projects/234/reports { author: 'xxxx', Separating metadata and content abstract: 'xxxx', } Scalability vs. orphaned data Response: report ID POST: /api/projects/234/reports/1 enctype=multipart/form-data

19 Option 3: Intermediate Storage Random key on client POST: /api/files/e b7-48ee-a e19efc4 enctype=multipart/form-data Then POST: /api/projects/234/reports { author: 'xxxx', abstract: 'xxxx', filename: 'xxxx', filesize: 222, href: '/api/files/e b7-48ee-a e19efc4' }