org.directwebremoting.servlet.UrlProcessor Maven / Gradle / Ivy

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DWR is easy Ajax for Java. It makes it simple to call Java code directly from Javascript. It gets rid of almost all the boiler plate code between the web browser and your Java code.
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/*
 * 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.IOException;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

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

import org.apache.commons.logging.LogFactory;
import org.apache.commons.logging.Log;
import org.directwebremoting.Container;
import org.directwebremoting.extend.Handler;
import org.directwebremoting.extend.InitializingBean;

/**
 * This is the main servlet that handles all the requests to DWR.
 * 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.
 * There are 5 things to do, in the order that you come across them:
 * 
 * The index test page that points at the classes
 * The class test page that lets you execute methods
 * The interface javascript that uses the engine to send requests
 * The engine javascript to form the iframe request and process replies
 * The exec 'page' that executes the method and returns data to the iframe
 * 
 * @author Joe Walker [joe at getahead dot ltd dot uk]
 */
public class UrlProcessor implements Handler, InitializingBean
{
    /* (non-Javadoc)
     * @see org.directwebremoting.InitializingBean#afterPropertiesSet(Container)
     */
    public void afterContainerSetup(Container container)
    {
        Collection beanNames = container.getBeanNames();
        for (String name : beanNames)
        {
            if (name.startsWith(PathConstants.URL_PREFIX))
            {
                Object bean = container.getBean(name);

                if (bean instanceof Handler)
                {
                    urlMapping.put(name.substring(PathConstants.URL_PREFIX.length()), bean);
                }
                else
                {
                    log.error("Discarding non Handler for " + name);
                }
            }
        }
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.Handler#handle(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
     */
    public void handle(HttpServletRequest request, HttpServletResponse response) throws IOException
    {
        try
        {
            String pathInfo = request.getPathInfo();
            contextPath = request.getContextPath();

            if (pathInfo == null || pathInfo.length() == 0 || "/".equals(pathInfo))
            {
                response.sendRedirect(contextPath + request.getServletPath() + indexHandlerUrl);
            }
            else
            {
                // Loop through all the known URLs
                for (Entry entry : urlMapping.entrySet())
                {
                    String url = entry.getKey();

                    // If this URL matches, call the handler
                    if (pathInfo.startsWith(url))
                    {
                        Handler handler = (Handler) entry.getValue();
                        handler.handle(request, response);
                        return;
                    }
                }

                notFoundHandler.handle(request, response);
            }
        }
        catch (Exception ex)
        {
            exceptionHandler.setException(ex);
            exceptionHandler.handle(request, response);
        }
    }

    /**
     * The contextPath cached from the last HTTP servlet request
     * @return the contextPath
     */
    public String getContextPath()
    {
        return contextPath;
    }

    /**
     * The URL for the {@link IndexHandler}
     * @param indexHandlerUrl the indexHandlerUrl to set
     */
    public void setIndexHandlerUrl(String indexHandlerUrl)
    {
        this.indexHandlerUrl = indexHandlerUrl;
    }

    /**
     * The URL for the {@link IndexHandler}
     */
    protected String indexHandlerUrl;

    /**
     * The mapping of URLs to {@link Handler}s
     */
    protected Map urlMapping = new HashMap();

    /**
     * The default if we have no other action (HTTP-404)
     */
    protected Handler notFoundHandler = new NotFoundHandler();

    /**
     * If execution fails, we do this (HTTP-501)
     */
    protected ExceptionHandler exceptionHandler = new ExceptionHandler();

    /**
     * The contextPath cached from the last HTTP servlet request
     */
    protected String contextPath = null;

    /**
     * The log stream
     */
    private static final Log log = LogFactory.getLog(UrlProcessor.class);
}