Tomcat example source code file (ErrorReportValve.java)

This example Tomcat source code file (ErrorReportValve.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Tomcat tags/keywords

hr, http, illegalstateexception, io, ioexception, request, response, response, servlet, servletexception, string, string, stringbuffer, stringbuffer, stringmanager, throwable, throwable, valvebase

The Tomcat ErrorReportValve.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


package org.apache.catalina.valves;


import java.io.IOException;
import java.io.Writer;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletResponse;

import org.apache.catalina.Globals;
import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.Response;
import org.apache.catalina.util.RequestUtil;
import org.apache.catalina.util.ServerInfo;
import org.apache.catalina.util.StringManager;

/**
 * <p>Implementation of a Valve that outputs HTML error pages.

 *
 * <p>This Valve should be attached at the Host level, although it will work
 * if attached to a Context.</p>
 *
 * <p>HTML code from the Cocoon 2 project.

 *
 * @author Remy Maucherat
 * @author Craig R. McClanahan
 * @author <a href="mailto:nicolaken@supereva.it">Nicola Ken Barozzi Aisa
 * @author <a href="mailto:stefano@apache.org">Stefano Mazzocchi
 * @author Yoav Shapira
 * @version $Revision: 543307 $ $Date: 2007-06-01 01:08:24 +0200 (ven., 01 juin 2007) $
 */

public class ErrorReportValve
    extends ValveBase {


    // ----------------------------------------------------- Instance Variables


    /**
     * The descriptive information related to this implementation.
     */
    private static final String info =
        "org.apache.catalina.valves.ErrorReportValve/1.0";


    /**
     * The StringManager for this package.
     */
    protected static StringManager sm =
        StringManager.getManager(Constants.Package);


    // ------------------------------------------------------------- Properties


    /**
     * Return descriptive information about this Valve implementation.
     */
    public String getInfo() {

        return (info);

    }


    // --------------------------------------------------------- Public Methods


    /**
     * Invoke the next Valve in the sequence. When the invoke returns, check
     * the response state, and output an error report is necessary.
     *
     * @param request The servlet request to be processed
     * @param response The servlet response to be created
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet error occurs
     */
    public void invoke(Request request, Response response)
        throws IOException, ServletException {

        // Perform the request
        getNext().invoke(request, response);

        Throwable throwable =
            (Throwable) request.getAttribute(Globals.EXCEPTION_ATTR);

        if (response.isCommitted()) {
            return;
        }

        if (throwable != null) {

            // The response is an error
            response.setError();

            // Reset the response (if possible)
            try {
                response.reset();
            } catch (IllegalStateException e) {
                ;
            }

            response.sendError
                (HttpServletResponse.SC_INTERNAL_SERVER_ERROR);

        }

        response.setSuspended(false);

        try {
            report(request, response, throwable);
        } catch (Throwable tt) {
            ;
        }

    }


    // ------------------------------------------------------ Protected Methods


    /**
     * Prints out an error report.
     *
     * @param request The request being processed
     * @param response The response being generated
     * @param throwable The exception that occurred (which possibly wraps
     *  a root cause exception
     */
    protected void report(Request request, Response response,
                          Throwable throwable) {

        // Do nothing on non-HTTP responses
        int statusCode = response.getStatus();

        // Do nothing on a 1xx, 2xx and 3xx status
        // Do nothing if anything has been written already
        if ((statusCode < 400) || (response.getContentCount() > 0))
            return;

        String message = RequestUtil.filter(response.getMessage());
        if (message == null)
            message = "";

        // Do nothing if there is no report for the specified status code
        String report = null;
        try {
            report = sm.getString("http." + statusCode, message);
        } catch (Throwable t) {
            ;
        }
        if (report == null)
            return;

        StringBuffer sb = new StringBuffer();

        sb.append("<html>