urlprocessor.java

Ajax 框架,可以用来做数型菜单或者联动下拉列表

/*
 * Copyright 2005 Joe Walker
 *
 * Licensed 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.directwebremoting.servlet;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.directwebremoting.Calls;
import org.directwebremoting.Container;
import org.directwebremoting.DebugPageGenerator;
import org.directwebremoting.DwrConstants;
import org.directwebremoting.Remoter;
import org.directwebremoting.Replies;
import org.directwebremoting.ScriptSessionManager;
import org.directwebremoting.WebContextFactory;
import org.directwebremoting.dwrp.DwrpHtmlJsMarshaller;
import org.directwebremoting.dwrp.DwrpPlainJsMarshaller;
import org.directwebremoting.impl.DefaultScriptSessionManager;
import org.directwebremoting.util.IdGenerator;
import org.directwebremoting.util.JavascriptUtil;
import org.directwebremoting.util.LocalUtil;
import org.directwebremoting.util.Logger;
import org.directwebremoting.util.MimeConstants;

/**
 * This is the main servlet that handles all the requests to DWR.
 * <p>It is on the large side because it can't use technologies like JSPs etc
 * since it all needs to be deployed in a single jar file, and while it might be
 * possible to integrate Velocity or similar I think simplicity is more
 * important, and there are only 2 real pages both script heavy in this servlet
 * anyway.</p>
 * <p>There are 5 things to do, in the order that you come across them:</p>
 * <ul>
 * <li>The index test page that points at the classes</li>
 * <li>The class test page that lets you execute methods</li>
 * <li>The interface javascript that uses the engine to send requests</li>
 * <li>The engine javascript to form the iframe request and process replies</li>
 * <li>The exec 'page' that executes the method and returns data to the iframe</li>
 * </ul>
 * @author Joe Walker [joe at getahead dot ltd dot uk]
 */
public class UrlProcessor
{
    /**
     * Handle servlet requests aimed at DWR
     * @param request The servlet request
     * @param response The servlet response
     * @throws IOException If there are IO issues
     */
    public void handle(HttpServletRequest request, HttpServletResponse response) throws IOException
    {
        try
        {
            String pathInfo = request.getPathInfo();
            String servletPath = request.getServletPath();
            String contextPath = request.getContextPath();

            if (nullPathInfoWorkaround && pathInfo == null)
            {
                pathInfo = request.getServletPath();
                servletPath = PathConstants.PATH_ROOT;
                log.debug("Default servlet suspected. pathInfo=" + pathInfo + "; contextPath=" + contextPath + "; servletPath=" + servletPath); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
            }

            if (pathInfo == null ||
                pathInfo.length() == 0 ||
                pathInfo.equals(PathConstants.PATH_ROOT))
            {
                response.sendRedirect(contextPath + servletPath + PathConstants.FILE_INDEX);
            }
            else if (pathInfo.startsWith(PathConstants.FILE_INDEX))
            {
                String page = debugPageGenerator.generateIndexPage(contextPath + servletPath);

                response.setContentType(MimeConstants.MIME_HTML);
                PrintWriter out = response.getWriter();
                out.print(page);
                response.flushBuffer();
            }
            else if (pathInfo.startsWith(PathConstants.PATH_TEST))
            {
                String scriptName = pathInfo;
                scriptName = LocalUtil.replace(scriptName, PathConstants.PATH_TEST, ""); //$NON-NLS-1$
                scriptName = LocalUtil.replace(scriptName, PathConstants.PATH_ROOT, ""); //$NON-NLS-1$

                String page = debugPageGenerator.generateTestPage(contextPath + servletPath, scriptName);

                response.setContentType(MimeConstants.MIME_HTML);
                PrintWriter out = response.getWriter();
                out.print(page);
                response.flushBuffer();
            }
            else if (pathInfo.startsWith(PathConstants.PATH_INTERFACE))
            {
                String scriptName = pathInfo;
                scriptName = LocalUtil.replace(scriptName, PathConstants.PATH_INTERFACE, ""); //$NON-NLS-1$
                scriptName = LocalUtil.replace(scriptName, PathConstants.EXTENSION_JS, ""); //$NON-NLS-1$
                String path = contextPath + servletPath;

                String script = remoter.generateInterfaceScript(scriptName, path);

                // Officially we should use MimeConstants.MIME_JS, but if we cheat and
                // use MimeConstants.MIME_PLAIN then it will be easier to read in a
                // browser window, and will still work just fine.
                response.setContentType(MimeConstants.MIME_PLAIN);
                PrintWriter out = response.getWriter();
                out.print(script);
                response.flushBuffer();
            }
            else if (pathInfo.startsWith(PathConstants.PATH_PLAINJS))
            {
                Calls calls = plainJsMarshaller.marshallInbound(request, response);
                Replies replies = remoter.execute(calls);
                plainJsMarshaller.marshallOutbound(replies, request, response);
            }
            else if (pathInfo.startsWith(PathConstants.PATH_HTMLJS))
            {
                Calls calls = htmlJsMarshaller.marshallInbound(request, response);
                Replies replies = remoter.execute(calls);
                htmlJsMarshaller.marshallOutbound(replies, request, response);
            }
            else if (pathInfo.equalsIgnoreCase(PathConstants.FILE_ENGINE))
            {
                doFile(request, response, PathConstants.FILE_ENGINE, MimeConstants.MIME_JS, true);
            }
            else if (pathInfo.equalsIgnoreCase(PathConstants.FILE_UTIL))
            {
                doFile(request, response, PathConstants.FILE_UTIL, MimeConstants.MIME_JS, false);
            }
            else if (pathInfo.startsWith(PathConstants.PATH_STATUS))
            {
                Container container = WebContextFactory.get().getContainer();
                ScriptSessionManager manager = (ScriptSessionManager) container.getBean(ScriptSessionManager.class.getName());
                if (manager instanceof DefaultScriptSessionManager)
                {
                    DefaultScriptSessionManager dssm = (DefaultScriptSessionManager) manager;
                    dssm.debug();
                }
            }
            else
            {
                log.warn("Page not found (" + pathInfo + "). In debug/test mode try viewing /[WEB-APP]/dwr/"); //$NON-NLS-1$ //$NON-NLS-2$
                response.sendError(HttpServletResponse.SC_NOT_FOUND);
            }
        }
        catch (Exception ex)
        {
            log.warn("Error: " + ex); //$NON-NLS-1$
            if (ex instanceof SecurityException && log.isDebugEnabled())
            {
                log.debug("- User Agent: " + request.getHeader(HttpConstants.HEADER_USER_AGENT)); //$NON-NLS-1$
                log.debug("- Remote IP:  " + request.getRemoteAddr()); //$NON-NLS-1$
                log.debug("- Request URL:" + request.getRequestURL()); //$NON-NLS-1$
                log.debug("- Query:      " + request.getQueryString()); //$NON-NLS-1$
                log.debug("- Method:     " + request.getMethod()); //$NON-NLS-1$
   
                ex.printStackTrace();
            }

            response.setContentType(MimeConstants.MIME_HTML);
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            PrintWriter out = response.getWriter();
            out.println("<html><head><title>Error</title</head><body>"); //$NON-NLS-1$
            out.println("<p><b>Error</b>: " + ex.getMessage() + "</p>"); //$NON-NLS-1$ //$NON-NLS-2$
            out.println("<p>For further information about DWR see:</p><ul>"); //$NON-NLS-1$
            out.println("<li><a href='http://getahead.ltd.uk/dwr/documentation'>DWR Documentation</a></li>"); //$NON-NLS-1$
            out.println("<li><a href='http://getahead.ltd.uk/dwr/support'>DWR Mailing List</a></li>"); //$NON-NLS-1$
            out.println("</ul>"); //$NON-NLS-1$
            out.println("<script type='text/javascript'>"); //$NON-NLS-1$
            out.println("alert('" + ex.getMessage() + "');"); //$NON-NLS-1$ //$NON-NLS-2$
            out.println("</script>"); //$NON-NLS-1$
            out.println("</body></html>"); //$NON-NLS-1$
            out.flush();
        }
    }

    /**
     * Basically a file servlet component that does some <b>very limitted</b>
     * EL type processing on the file. See the source for the cheat.
     * @param request The request from the browser
     * @param response The response channel
     * @param path The path to search for, process and output
     * @param mimeType The mime type to use for this output file
     * @param dynamic Should the script be recalculated each time?
     * @throws IOException If writing to the output fails
     */
    protected void doFile(HttpServletRequest request, HttpServletResponse response, String path, String mimeType, boolean dynamic) throws IOException
    {
        if (!dynamic && isUpToDate(request, path))
        {
            response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
            return;
        }

        String output;

        synchronized (scriptCache)
        {
            output = (String) scriptCache.get(path);
            if (output == null)
            {
                StringBuffer buffer = new StringBuffer();

                String resource = DwrConstants.PACKAGE + path;
                InputStream raw = getClass().getResourceAsStream(resource);
                if (raw == null)
                {
                    throw new IOException("Failed to find resource: " + resource); //$NON-NLS-1$
                }

                BufferedReader in = new BufferedReader(new InputStreamReader(raw));
                while (true)
                {
                    String line = in.readLine();
                    if (line == null)
                    {
                        break;
                    }

                    if (dynamic)
                    {
                        if (line.indexOf(PARAM_HTTP_SESSIONID) != -1)
                        {
                            line = LocalUtil.replace(line, PARAM_HTTP_SESSIONID, request.getSession(true).getId());
                        }

                        if (line.indexOf(PARAM_SCRIPT_SESSIONID) != -1)
                        {
                            line = LocalUtil.replace(line, PARAM_SCRIPT_SESSIONID, generator.generateId(pageIdLength));
                        }
                    }

                    buffer.append(line);
                    buffer.append('\n');
                }