applicationdispatcher.java

业界著名的tomcat服务器的最新6.0的源代码。

/*
 * 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.core;

import java.io.IOException;
import java.io.PrintWriter;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;

import javax.servlet.RequestDispatcher;
import javax.servlet.Servlet;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletRequestWrapper;
import javax.servlet.ServletResponse;
import javax.servlet.ServletResponseWrapper;
import javax.servlet.UnavailableException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.catalina.Context;
import org.apache.catalina.Globals;
import org.apache.catalina.InstanceEvent;
import org.apache.catalina.Wrapper;
import org.apache.catalina.connector.ClientAbortException;
import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.RequestFacade;
import org.apache.catalina.connector.Response;
import org.apache.catalina.connector.ResponseFacade;
import org.apache.catalina.util.InstanceSupport;
import org.apache.catalina.util.StringManager;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;

/**
 * Standard implementation of <code>RequestDispatcher</code> that allows a
 * request to be forwarded to a different resource to create the ultimate
 * response, or to include the output of another resource in the response
 * from this resource.  This implementation allows application level servlets
 * to wrap the request and/or response objects that are passed on to the
 * called resource, as long as the wrapping classes extend
 * <code>javax.servlet.ServletRequestWrapper</code> and
 * <code>javax.servlet.ServletResponseWrapper</code>.
 *
 * @author Craig R. McClanahan
 * @version $Revision: 505593 $ $Date: 2007-02-10 01:54:56 +0100 (sam., 10 févr. 2007) $
 */

final class ApplicationDispatcher
    implements RequestDispatcher {


    protected class PrivilegedForward implements PrivilegedExceptionAction {
        private ServletRequest request;
        private ServletResponse response;

        PrivilegedForward(ServletRequest request, ServletResponse response)
        {
            this.request = request;
            this.response = response;
        }

        public Object run() throws java.lang.Exception {
            doForward(request,response);
            return null;
        }
    }

    protected class PrivilegedInclude implements PrivilegedExceptionAction {
        private ServletRequest request;
        private ServletResponse response;

        PrivilegedInclude(ServletRequest request, ServletResponse response)
        {
            this.request = request;
            this.response = response;
        }

        public Object run() throws ServletException, IOException {
            doInclude(request,response);
            return null;
        }
    }

    
    /**
     * Used to pass state when the request dispatcher is used. Using instance
     * variables causes threading issues and state is too complex to pass and
     * return single ServletRequest or ServletResponse objects.
     */
    private class State {
        State(ServletRequest request, ServletResponse response,
                boolean including) {
            this.outerRequest = request;
            this.outerResponse = response;
            this.including = including;
        }

        /**
         * The outermost request that will be passed on to the invoked servlet.
         */
        ServletRequest outerRequest = null;


        /**
         * The outermost response that will be passed on to the invoked servlet.
         */
        ServletResponse outerResponse = null;
        
        /**
         * The request wrapper we have created and installed (if any).
         */
        ServletRequest wrapRequest = null;


        /**
         * The response wrapper we have created and installed (if any).
         */
        ServletResponse wrapResponse = null;
        
        /**
         * Are we performing an include() instead of a forward()?
         */
        boolean including = false;
    }

    // ----------------------------------------------------------- Constructors


    /**
     * Construct a new instance of this class, configured according to the
     * specified parameters.  If both servletPath and pathInfo are
     * <code>null</code>, it will be assumed that this RequestDispatcher
     * was acquired by name, rather than by path.
     *
     * @param wrapper The Wrapper associated with the resource that will
     *  be forwarded to or included (required)
     * @param requestURI The request URI to this resource (if any)
     * @param servletPath The revised servlet path to this resource (if any)
     * @param pathInfo The revised extra path information to this resource
     *  (if any)
     * @param queryString Query string parameters included with this request
     *  (if any)
     * @param name Servlet name (if a named dispatcher was created)
     *  else <code>null</code>
     */
    public ApplicationDispatcher
        (Wrapper wrapper, String requestURI, String servletPath,
         String pathInfo, String queryString, String name) {

        super();

        // Save all of our configuration parameters
        this.wrapper = wrapper;
        this.context = (Context) wrapper.getParent();
        this.requestURI = requestURI;
        this.servletPath = servletPath;
        this.pathInfo = pathInfo;
        this.queryString = queryString;
        this.name = name;
        if (wrapper instanceof StandardWrapper)
            this.support = ((StandardWrapper) wrapper).getInstanceSupport();
        else
            this.support = new InstanceSupport(wrapper);

        if ( log.isDebugEnabled() )
            log.debug("servletPath=" + this.servletPath + ", pathInfo=" +
                this.pathInfo + ", queryString=" + queryString +
                ", name=" + this.name);

    }


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

    private static Log log = LogFactory.getLog(ApplicationDispatcher.class);

    /**
     * The Context this RequestDispatcher is associated with.
     */
    private Context context = null;


    /**
     * Descriptive information about this implementation.
     */
    private static final String info =
        "org.apache.catalina.core.ApplicationDispatcher/1.0";


    /**
     * The servlet name for a named dispatcher.
     */
    private String name = null;


    /**
     * The extra path information for this RequestDispatcher.
     */
    private String pathInfo = null;


    /**
     * The query string parameters for this RequestDispatcher.
     */
    private String queryString = null;


    /**
     * The request URI for this RequestDispatcher.
     */
    private String requestURI = null;


    /**
     * The servlet path for this RequestDispatcher.
     */
    private String servletPath = null;


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


    /**
     * The InstanceSupport instance associated with our Wrapper (used to
     * send "before dispatch" and "after dispatch" events.
     */
    private InstanceSupport support = null;


    /**
     * The Wrapper associated with the resource that will be forwarded to
     * or included.
     */
    private Wrapper wrapper = null;


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


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

        return (info);

    }


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


    /**
     * Forward this request and response to another resource for processing.
     * Any runtime exception, IOException, or ServletException thrown by the
     * called servlet will be propogated to the caller.
     *
     * @param request The servlet request to be forwarded
     * @param response The servlet response to be forwarded
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet exception occurs
     */
    public void forward(ServletRequest request, ServletResponse response)
        throws ServletException, IOException
    {
        if (Globals.IS_SECURITY_ENABLED) {
            try {
                PrivilegedForward dp = new PrivilegedForward(request,response);
                AccessController.doPrivileged(dp);
            } catch (PrivilegedActionException pe) {
                Exception e = pe.getException();
                if (e instanceof ServletException)
                    throw (ServletException) e;
                throw (IOException) e;
            }
        } else {
            doForward(request,response);
        }
    }

    private void doForward(ServletRequest request, ServletResponse response)
        throws ServletException, IOException
    {
        
        // Reset any output that has been buffered, but keep headers/cookies
        if (response.isCommitted()) {
            if ( log.isDebugEnabled() )
                log.debug("  Forward on committed response --> ISE");
            throw new IllegalStateException
                (sm.getString("applicationDispatcher.forward.ise"));
        }
        try {
            response.resetBuffer();
        } catch (IllegalStateException e) {
            if ( log.isDebugEnabled() )
                log.debug("  Forward resetBuffer() returned ISE: " + e);
            throw e;
        }

        // Set up to handle the specified request and response
        State state = new State(request, response, false);

        if (Globals.STRICT_SERVLET_COMPLIANCE) {
            // Check SRV.8.2 / SRV.14.2.5.1 compliance
            checkSameObjects(request, response);
        }

        // Identify the HTTP-specific request and response objects (if any)
        HttpServletRequest hrequest = null;
        if (request instanceof HttpServletRequest)
            hrequest = (HttpServletRequest) request;
        HttpServletResponse hresponse = null;
        if (response instanceof HttpServletResponse)
            hresponse = (HttpServletResponse) response;

        // Handle a non-HTTP forward by passing the existing request/response
        if ((hrequest == null) || (hresponse == null)) {