[WW-4588] Improve the Struts2 Rest plugin to honor Accept header

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.3.24
• Fix Version/s: 2.3.28, 2.5
• Component/s: Plugin - REST
• Labels: rest struts2

Environment

tomcat

• Assignee: Unassigned
• Reporter: Rich Peters
• Created: 14/Jan/16 16:08
• Updated: 29/Mar/16 10:14
• Resolved: 20/Jan/16 15:17

Description

Currently the rest plugin primarily looks at the url extension to connect the proper content type handlers. This should be extended to use the Accept and Content-Type headers to drive the content-type handlers when no extension is present. Note that the plugin currently partially handles the case for input request using the content-type header, but can be overridden by the extension.

In a use case, if a request specifies in the header that the Content-Type is application/json, the input request data is converted to the json data format. If a request specifies the Accept:application/json header , the output data will be converted to json. This is cleaner than specifying the extension in a lot of cases where the application rest urls have to be generated in javascript.

a short unit test shows how the accept header is ignored:

    public void testObtainingHandlerForResponseByAcceptHeader() throws Exception {

        // given
        final DefaultContentTypeHandlerManager handlerManager = new DefaultContentTypeHandlerManager();
        handlerManager.setContainer(new DummyContainer("application/json", "json"));

        MockHttpServletRequest request = new MockHttpServletRequest();
        request.setContentType("application/json;charset=UTF-8");
        request.addHeader("accept","application/json;charset=UTF-8");
        request.setRequestURI("/index");

        final MockHttpServletResponse response = new MockHttpServletResponse();
        response.setContentType("application/json;charset=UTF-8");

        // when
        ContentTypeHandler handler = handlerManager.getHandlerForResponse(request,response);

        // then
        assertNotNull(handler);
        assertEquals("application/json", handler.getContentType());
        assertEquals("json", handler.getExtension());
    }

the output show the failure to acquire a handler:

junit.framework.AssertionFailedError: null

	at junit.framework.Assert.fail(Assert.java:47)
	at junit.framework.Assert.assertTrue(Assert.java:20)
	at junit.framework.Assert.assertNotNull(Assert.java:214)
	at junit.framework.Assert.assertNotNull(Assert.java:207)
	at org.apache.struts2.rest.DefaultContentTypeHandlerManagerTest.testObtainingHandlerForResponseByAcceptHeader(DefaultContentTypeHandlerManagerTest.java:104)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:497)
	at junit.framework.TestCase.runTest(TestCase.java:168)
	at junit.framework.TestCase.runBare(TestCase.java:134)
	at junit.framework.TestResult$1.protect(TestResult.java:110)
	at junit.framework.TestResult.runProtected(TestResult.java:128)
	at junit.framework.TestResult.run(TestResult.java:113)
	at junit.framework.TestCase.run(TestCase.java:124)
	at junit.framework.TestSuite.runTest(TestSuite.java:243)
	at junit.framework.TestSuite.run(TestSuite.java:238)
	at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:83)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74)

FWIW: Attached is a modified version of the 2.3.24.1 file that implements this