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TOTD #57: Jersey Client API - simple and easy to use

TOTD #56 explains how to create a RESTful Web service endpoint using Jersey and publish the resource using JSON representation. The blog entry showed how the endpoint can be accessed from a Web browser. This Tip Of The Day explains how to use Jersey Client APIs to invoke the published endpoint.

Lets get started!

1. Create a new directory "./src/test/java/org/glassfish/samples"
2. Add a test
1. Add a template test file "AppTest.java" as shown below:
   
   

   package org.glassfish.samples; import junit.framework.Test; import junit.framework.TestCase; import junit.framework.TestSuite; /**  * Unit test for simple App.  */ public class AppTest     extends TestCase {     /**      * Create the test case      *      * @param testName name of the test case      */     public AppTest( String testName )     {         super( testName );     }     /**      * @return the suite of tests being tested      */     public static Test suite()     {         return new TestSuite( AppTest.class );     }     /**      * Rigourous Test :-)      */     public void testApp()     {         assertTrue(true);     } }

2. Add a new method "createResource()" as:
   
   

   private WebResource createResource() {         Client client = Client.create();         WebResource resource = client.resource("http://localhost:8080/helloworld-webapp/webresources/myresource");         return resource;     }

   
   This code creates a default instance of Jersey Client and creates a Web resource from that client for the URI passed as an argument.
3. Change the implementation of "testApp()" method as:
   
   

   Greeting result = createResource().get(Greeting.class);         assertTrue(result.greeting.equals("Hi there!"));

   
   This invokes the GET method on the resource by passing specific type and compares the returned and expected value.
   
4. Add the following "imports":
   
   

   import com.sun.jersey.api.client.Client; import com.sun.jersey.api.client.WebResource;

5. Copy "Greeting.java" from TOTD #56 to "./src/test/java/org/glassfish/samples" directory.
3. Run the test
1. Deploy the endpoint as "mvn glassfish:run".
2. Run the test as "mvn test". The following output is shown:
   
   

   ~/samples/jersey/helloworld-webapp >mvn test [INFO] Scanning for projects... [INFO] ------------------------------------------------------------------------ [INFO] Building helloworld-webapp Jersey Webapp [INFO]    task-segment: [test] [INFO] ------------------------------------------------------------------------ [INFO] [resources:resources] [INFO] Using default encoding to copy filtered resources. [INFO] [compiler:compile] [INFO] Nothing to compile - all classes are up to date [INFO] [resources:testResources] [INFO] Using default encoding to copy filtered resources. [INFO] [compiler:testCompile] [INFO] Compiling 1 source file to /Users/arungupta/samples/jersey/helloworld-webapp/target/test-classes [INFO] [surefire:test] [INFO] Surefire report directory: /Users/arungupta/samples/jersey/helloworld-webapp/target/surefire-reports -------------------------------------------------------  T E S T S ------------------------------------------------------- Running org.glassfish.samples.AppTest Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.587 sec Results : Tests run: 1, Failures: 0, Errors: 0, Skipped: 0 [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESSFUL [INFO] ------------------------------------------------------------------------ [INFO] Total time: 4 seconds [INFO] Finished at: Mon Nov 24 16:50:17 PST 2008 [INFO] Final Memory: 18M/43M [INFO] ------------------------------------------------------------------------

4. View request and response messages
1. Change the implementation of "createResource()" method as (changes highlighted in bold):
   
   

   Client client = Client.create();         WebResource resource = client.resource("http://localhost:8080/helloworld-webapp/webresources/myresource");         resource.addFilter(new LoggingFilter());         return resource;

2. Running the tests as "mvn test" now shows the output, with request and response messages, as shown below:
   
   

   Running org.glassfish.samples.AppTest 1 * Out-bound request 1 > GET http://localhost:8080/helloworld-webapp/webresources/myresource 1 > 1 < 200 1 < X-Powered-By: Servlet/2.5 1 < Transfer-Encoding: chunked 1 < Content-Type: application/json 1 < Server: GlassFish/v3 1 < Date: Tue, 25 Nov 2008 07:07:51 GMT 1 < {"greeting":"Hi there!"} 1 * In-bound response Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 1.074 sec

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