allow for writing the response directly in a Portlet @ExceptionHandler method (like in the Servlet equivalent)

org.springframework.web.portlet/src/main/java/org/springframework/web/portlet/mvc/annotation/AnnotationMethodHandlerExceptionResolver.java

@@ -74,16 +74,18 @@ public class AnnotationMethodHandlerExceptionResolver extends AbstractHandlerExc
 
 
 	/**
-	 * Set a custom ArgumentResolvers to use for special method parameter types. Such a custom ArgumentResolver will kick
-	 * in first, having a chance to resolve an argument value before the standard argument handling kicks in.
+	 * Set a custom ArgumentResolvers to use for special method parameter types.
+	 * <p>Such a custom ArgumentResolver will kick in first, having a chance to resolve
+	 * an argument value before the standard argument handling kicks in.
 	 */
 	public void setCustomArgumentResolver(WebArgumentResolver argumentResolver) {
 		this.customArgumentResolvers = new WebArgumentResolver[]{argumentResolver};
 	}
 
 	/**
-	 * Set one or more custom ArgumentResolvers to use for special method parameter types. Any such custom ArgumentResolver
-	 * will kick in first, having a chance to resolve an argument value before the standard argument handling kicks in.
+	 * Set one or more custom ArgumentResolvers to use for special method parameter types.
+	 * <p>Any such custom ArgumentResolver will kick in first, having a chance to resolve
+	 * an argument value before the standard argument handling kicks in.
 	 */
 	public void setCustomArgumentResolvers(WebArgumentResolver[] argumentResolvers) {
 		this.customArgumentResolvers = argumentResolvers;
@@ -366,7 +368,7 @@ public class AnnotationMethodHandlerExceptionResolver extends AbstractHandlerExc
 			return new ModelAndView((String) returnValue);
 		}
 		else if (returnValue == null) {
-			return null;
+			return new ModelAndView();
 		}
 		else {
 			throw new IllegalArgumentException("Invalid handler method return value: " + returnValue);

org.springframework.web.portlet/src/test/java/org/springframework/web/portlet/mvc/annotation/Portlet20AnnotationControllerTests.java

@@ -86,7 +86,6 @@ import org.springframework.web.context.request.WebRequest;
 import org.springframework.web.context.support.GenericWebApplicationContext;
 import org.springframework.web.portlet.DispatcherPortlet;
 import org.springframework.web.portlet.ModelAndView;
-import org.springframework.web.portlet.bind.MissingPortletRequestParameterException;
 import org.springframework.web.portlet.bind.annotation.ActionMapping;
 import org.springframework.web.portlet.bind.annotation.EventMapping;
 import org.springframework.web.portlet.bind.annotation.RenderMapping;
@@ -519,6 +518,17 @@ public class Portlet20AnnotationControllerTests {
 		portlet.render(request, response);
 		assertEquals("myLargeView-value2", response.getContentAsString());
 
+		actionRequest = new MockActionRequest("error");
+		actionResponse = new MockActionResponse();
+		portlet.processAction(actionRequest, actionResponse);
+
+		request = new MockRenderRequest(PortletMode.VIEW, WindowState.MAXIMIZED);
+		request.setParameters(actionResponse.getRenderParameterMap());
+		request.setSession(actionRequest.getPortletSession());
+		response = new MockRenderResponse();
+		portlet.render(request, response);
+		assertEquals("XXX", response.getContentAsString());
+
 		MockEventRequest eventRequest = new MockEventRequest(new MockEvent("event1"));
 		MockEventResponse eventResponse = new MockEventResponse();
 		portlet.processEvent(eventRequest, eventResponse);
@@ -1029,6 +1039,11 @@ public class Portlet20AnnotationControllerTests {
 			response.setRenderParameter("test", "value2");
 		}
 
+		@ActionMapping("error")
+		public void myError(StateAwareResponse response) {
+			throw new IllegalStateException("XXX");
+		}
+
 		@EventMapping("event1")
 		public void myHandle(EventResponse response) throws IOException {
 			response.setRenderParameter("test", "value3");
@@ -1049,6 +1064,11 @@ public class Portlet20AnnotationControllerTests {
 			writer.write("myView");
 		}
 
+		@ExceptionHandler
+		public void handleException(Exception ex, Writer writer) throws IOException {
+			writer.write(ex.getMessage());
+		}
+
 		@ResourceMapping("resource1")
 		public void myResource(Writer writer) throws IOException {
 			writer.write("myResource");

org.springframework.web.servlet/src/test/java/org/springframework/web/servlet/mvc/annotation/ServletAnnotationControllerTests.java

@@ -114,6 +114,7 @@ import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.ResponseBody;
 import org.springframework.web.bind.annotation.ResponseStatus;
 import org.springframework.web.bind.annotation.SessionAttributes;
+import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.bind.support.ConfigurableWebBindingInitializer;
 import org.springframework.web.bind.support.WebArgumentResolver;
 import org.springframework.web.bind.support.WebBindingInitializer;
@@ -1769,13 +1770,18 @@ public class ServletAnnotationControllerTests {
 
 		@RequestMapping("")
 		public void myPath2(HttpServletResponse response) throws IOException {
-			response.getWriter().write("test");
+			throw new IllegalStateException("test");
 		}
 
 		@RequestMapping("/bar")
 		public void myPath3(HttpServletResponse response) throws IOException {
 			response.getWriter().write("testX");
 		}
+
+		@ExceptionHandler
+		public void myPath2(Exception ex, HttpServletResponse response) throws IOException {
+			response.getWriter().write(ex.getMessage());
+		}
 	}
 
 	@Controller