Add error request attribute for 500 reponses

DefaultHandlerExceptionResolver and ResponseEntityExceptionHandler now
both set the "javax.servlet.error.exception" request attribute to the
raised exception, allowing custom error pages configured via web.xml.

Issue: SPR-9653

Author: rstoyanchev

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseEntityExceptionHandler.java

@@ -179,6 +179,10 @@ else if (ex instanceof BindException) {
 	protected ResponseEntity<Object> handleExceptionInternal(Exception ex, Object body,
 			HttpHeaders headers, HttpStatus status, WebRequest request) {
 
+		if (HttpStatus.INTERNAL_SERVER_ERROR.equals(status)) {
+			request.setAttribute("javax.servlet.error.exception", ex, WebRequest.SCOPE_REQUEST);
+		}
+
 		return new ResponseEntity<Object>(body, headers, status);
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/support/DefaultHandlerExceptionResolver.java

@@ -294,10 +294,21 @@ protected ModelAndView handleServletRequestBindingException(ServletRequestBindin
 	protected ModelAndView handleConversionNotSupported(ConversionNotSupportedException ex,
 			HttpServletRequest request, HttpServletResponse response, Object handler) throws IOException {
 
-		response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
+		sendServerError(ex, request, response);
 		return new ModelAndView();
 	}
 
+	/**
+	 * Invoked to send a server error. Sets the status to 500 and also sets the
+	 * request attribute "javax.servlet.error.exception" to the Exception.
+	 */
+	protected void sendServerError(Exception ex,
+			HttpServletRequest request, HttpServletResponse response) throws IOException {
+
+		request.setAttribute("javax.servlet.error.exception", ex);
+		response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
+	}
+
 	/**
 	 * Handle the case when a {@link org.springframework.web.bind.WebDataBinder} conversion error occurs.
 	 * <p>The default implementation sends an HTTP 400 error, and returns an empty {@code ModelAndView}.
@@ -352,7 +363,7 @@ protected ModelAndView handleHttpMessageNotReadable(HttpMessageNotReadableExcept
 	protected ModelAndView handleHttpMessageNotWritable(HttpMessageNotWritableException ex,
 			HttpServletRequest request, HttpServletResponse response, Object handler) throws IOException {
 
-		response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
+		sendServerError(ex, request, response);
 		return new ModelAndView();
 	}
 

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ResponseEntityExceptionHandlerTests.java

@@ -16,6 +16,7 @@
 package org.springframework.web.servlet.mvc.method.annotation;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
 
 import java.lang.reflect.Method;
@@ -204,6 +205,12 @@ public void controllerAdvice() throws Exception {
 
 	private ResponseEntity<Object> testException(Exception ex) {
 		ResponseEntity<Object> responseEntity = this.exceptionHandlerSupport.handleException(ex, this.request);
+
+		// SPR-9653
+		if (HttpStatus.INTERNAL_SERVER_ERROR.equals(responseEntity.getStatusCode())) {
+			assertSame(ex, this.servletRequest.getAttribute("javax.servlet.error.exception"));
+		}
+
 		this.defaultExceptionResolver.resolveException(this.servletRequest, this.servletResponse, null, ex);
 
 		assertEquals(this.servletResponse.getStatus(), responseEntity.getStatusCode().value());

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/support/DefaultHandlerExceptionResolverTests.java

@@ -18,12 +18,14 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
 
 import java.util.Collections;
 
 import org.junit.Before;
 import org.junit.Test;
+import org.springframework.beans.ConversionNotSupportedException;
 import org.springframework.beans.TestBean;
 import org.springframework.beans.TypeMismatchException;
 import org.springframework.core.MethodParameter;
@@ -169,6 +171,19 @@ public void handleBindException() throws Exception {
 		assertEquals("Invalid status code", 400, response.getStatus());
 	}
 
+	@Test
+	public void handleConversionNotSupportedException() throws Exception {
+		ConversionNotSupportedException ex =
+				new ConversionNotSupportedException(new Object(), String.class, new Exception());
+		ModelAndView mav = exceptionResolver.resolveException(request, response, null, ex);
+		assertNotNull("No ModelAndView returned", mav);
+		assertTrue("No Empty ModelAndView returned", mav.isEmpty());
+		assertEquals("Invalid status code", 500, response.getStatus());
+
+		// SPR-9653
+		assertSame(ex, request.getAttribute("javax.servlet.error.exception"));
+	}
+
 	public void handle(String arg) {
 	}