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Posted to dev@struts.apache.org by ge...@apache.org on 2005/07/07 00:38:13 UTC
svn commit: r209532 -
/struts/core/trunk/src/share/org/apache/struts/action/ExceptionHandler.java
Author: germuska
Date: Wed Jul 6 15:38:10 2005
New Revision: 209532
URL: http://svn.apache.org/viewcvs?rev=209532&view=rev
Log:
Modify ExceptionHandler to take into account the case when the HttpServletResponse is "committed".
This happens often when Tiles is being used, and results in the dreaded "blank screen."
Henceforth, by default, the ExceptionHandler tests response.isCommitted() and when true, in the normal case, simply
"includes" the configured view path, rather than forwarding to it.
For users who want to use an alternate view path in this case (perhaps a simpler one which fits better into
a partially rendered tileset), it is possible to set an alternate path for use only in this case, and for users
who don't want anything done when the response is committed, that can also be configured. See the JavaDoc for details.
Modified:
struts/core/trunk/src/share/org/apache/struts/action/ExceptionHandler.java
Modified: struts/core/trunk/src/share/org/apache/struts/action/ExceptionHandler.java
URL: http://svn.apache.org/viewcvs/struts/core/trunk/src/share/org/apache/struts/action/ExceptionHandler.java?rev=209532&r1=209531&r2=209532&view=diff
==============================================================================
--- struts/core/trunk/src/share/org/apache/struts/action/ExceptionHandler.java (original)
+++ struts/core/trunk/src/share/org/apache/struts/action/ExceptionHandler.java Wed Jul 6 15:38:10 2005
@@ -18,6 +18,9 @@
package org.apache.struts.action;
+import java.io.IOException;
+
+import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@@ -38,6 +41,49 @@
*/
public class ExceptionHandler {
+ /**
+ * <p>The name of a configuration property which can be set to specify an alternative path which should be used
+ * when the <code>HttpServletResponse</code> has already been committed.</p>
+ * <p>To use this, in your <code>struts-config.xml</code> specify the exception handler like this:
+ * <pre>
+ * <exception
+ * key="GlobalExceptionHandler.default"
+ * type="java.lang.Exception"
+ * path="/ErrorPage.jsp">
+ * <set-property key="INCLUDE_PATH" value="/error.jsp" />
+ * </exception>
+ * </pre>
+ * </p>
+ * <p>You would want to use this when your normal ExceptionHandler path is a Tiles definition or otherwise unsuitable for use
+ * in an <code>include</code> context. If you do not use this, and you do not specify "SILENT_IF_COMMITTED" then the
+ * ExceptionHandler will attempt to forward to the same path which would be used in normal circumstances,
+ * specified using the "path" attribute in the <exception> element.</p>
+ * @since Struts 1.3
+ */
+ public static final String INCLUDE_PATH = "INCLUDE_PATH";
+
+ /**
+ * <p>The name of a configuration property which indicates that Struts should do nothing
+ * if the response has already been committed. This suppresses the default behavior, which is
+ * to use an "include" rather than a "forward" in this case in hopes of providing some meaningful
+ * information to the browser.</p>
+ * <p>To use this, in your <code>struts-config.xml</code> specify the exception handler like this:
+ * <pre>
+ * <exception
+ * key="GlobalExceptionHandler.default"
+ * type="java.lang.Exception"
+ * path="/ErrorPage.jsp">
+ * <set-property key="SILENT_IF_COMMITTED" value="true" />
+ * </exception>
+ * </pre>
+ * To be effective, this value must be defined to the literal String "true". If it is not defined or
+ * defined to any other value, the default behavior will be used.
+ * </p>
+ * <p>You only need to use this if you do not want error information displayed in the browser when Struts
+ * intercepts an exception after the response has been committed.</p>
+ * @since Struts 1.3
+ */
+ public static final String SILENT_IF_COMMITTED = "SILENT_IF_COMMITTED";
/**
* <p>Commons logging instance.</p>
@@ -81,6 +127,7 @@
HttpServletResponse response)
throws ServletException {
+ log.debug("ExceptionHandler executing for exception " + ex);
ActionForward forward = null;
ActionMessage error = null;
String property = null;
@@ -107,13 +154,99 @@
// Store the exception
request.setAttribute(Globals.EXCEPTION_KEY, ex);
this.storeException(request, property, error, forward, ae.getScope());
+ if (!response.isCommitted()) return forward;
+ log.debug("Response is already committed, so forwarding will not work. Attempt alternate handling.");
+ if (!silent(ae)) {
+ handleCommittedResponse(ex, ae, mapping, formInstance, request,response, forward);
+ } else {
+ log.warn("ExceptionHandler configured with " + SILENT_IF_COMMITTED + " and response is committed.",ex);
+ }
+ return null;
+
+ }
- return forward;
+ /**
+ * <p>Attempt to give good information when the response has already been committed when the exception was thrown.
+ * This happens often when Tiles is used. Base implementation will see if the INCLUDE_PATH property has been set,
+ * or if not, it will attempt to use the same path to which control would have been forwarded.</p>
+ * @param ex
+ * @param config
+ * @param mapping
+ * @param formInstance
+ * @param request
+ * @param response
+ * @param actionForward
+ * @since Struts 1.3
+ */
+ protected void handleCommittedResponse(
+ Exception ex,
+ ExceptionConfig config,
+ ActionMapping mapping,
+ ActionForm formInstance,
+ HttpServletRequest request,
+ HttpServletResponse response,
+ ActionForward actionForward) {
+ String includePath = determineIncludePath(config, actionForward);
+ if (includePath != null) {
+ if (includePath.startsWith("/")) {
+ log.debug("response committed, but attempt to include results of actionForward path");
+ RequestDispatcher requestDispatcher = request.getRequestDispatcher(includePath);
+ try {
+ requestDispatcher.include(request, response);
+ return;
+ } catch (IOException e) {
+ log.error("IOException when trying to include the error page path " + includePath,e);
+ } catch (ServletException e) {
+ log.error("ServletException when trying to include the error page path " + includePath,e);
+ }
+ } else {
+ log.warn("Suspicious includePath doesn't seem likely to work, so skipping it: " + includePath + "; expected path to start with '/'");
+ }
+ }
+ log.debug("Include not available or failed; try writing to the response directly.");
+ try {
+ response.getWriter().println("Unexpected error: " + ex);
+ response.getWriter().println("<!-- ");
+ ex.printStackTrace(response.getWriter());
+ response.getWriter().println("-->");
+ } catch (IOException e) {
+ log.error("Error giving minimal information about exception", e);
+ log.error("Original exception: ", ex);
+ }
}
/**
+ * <p>Return a path to which an include should be attempted in the case when the response was committed
+ * before the <code>ExceptionHandler</code> was invoked. </p>
+ * <p>If the <code>ExceptionConfig</code> has the property <code>INCLUDE_PATH</code> defined, then the value
+ * of that property will be returned.</p>
+ * @param config
+ * @param actionForward
+ * @return
+ * @since Struts 1.3
+ */
+ protected String determineIncludePath(ExceptionConfig config, ActionForward actionForward) {
+ String includePath = config.getProperty("INCLUDE_PATH");
+ if (includePath == null) {
+ includePath = actionForward.getPath();
+ }
+ return includePath;
+ }
+
+ /**
+ * Determine teh boo
+ * @param config
+ * @param string
+ * @return
+ */
+ private boolean booleanProperty(ExceptionConfig config, String string) {
+ // TODO Auto-generated method stub
+ return false;
+ }
+
+ /**
* <p>Logs the <code>Exception</code> using commons-logging.</p>
* @param e The Exception to log.
* @since Struts 1.2
@@ -191,5 +324,15 @@
}
}
+ /**
+ * <p>Indicate whether this Handler has been configured to be silent. In the base implementation, this is
+ * done by specifying the value <code>"true"</code> for the property "SILENT_IF_COMMITTED" in the ExceptionConfig.</p>
+ * @param config
+ * @return
+ * @since Struts 1.3
+ */
+ private boolean silent(ExceptionConfig config) {
+ return "true".equals(config.getProperty(SILENT_IF_COMMITTED));
+ }
}
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