jnlpdownloadservlet.java

编写程序

/*
 * @(#)JnlpDownloadServlet.java	1.8 03/01/23
 * 
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package jnlp.sample.servlet;

import java.io.*;
import java.util.*;
import java.net.*;
import javax.servlet.*;
import javax.servlet.http.*;

/**
 * This Servlet class is an implementation of JNLP Specification's
 * Download Protocols.
 *
 * All requests to this servlet is in the form of HTTP GET commands.
 * The parameters that are needed are:
 * <ul>
 * <li><code>arch</code>,
 * <li><code>os</code>,
 * <li><code>locale</code>,
 * <li><code>version-id</code> or <code>platform-version-id</code>,
 * <li><code>current-version-id</code>,
 * <li>code>known-platforms</code>
 * </ul>
 * <p>
 *
 * @version 1.8 01/23/03
 */
public class JnlpDownloadServlet extends HttpServlet {
    
    // Localization
    private static ResourceBundle  _resourceBundle = null; 
    
    // Servlet configuration
    private static final String PARAM_JNLP_EXTENSION    = "jnlp-extension";    
    private static final String PARAM_JAR_EXTENSION     = "jar-extension";    
    
    // Servlet configuration
    private Logger _log = null;
    
    private JnlpFileHandler _jnlpFileHandler = null;
    private JarDiffHandler  _jarDiffHandler = null;
    private ResourceCatalog _resourceCatalog = null;    
    
    /** Initialize servlet */
    public void init(ServletConfig config) throws ServletException {
        super.init(config);
	
	
	// Setup logging
	_log = new Logger(config, getResourceBundle());
	_log.addDebug("Initializing");
	
	// Get extension from Servlet configuration, or use default	
	JnlpResource.setDefaultExtensions(
	    config.getInitParameter(PARAM_JNLP_EXTENSION), 
	    config.getInitParameter(PARAM_JAR_EXTENSION));		
	
	_jnlpFileHandler = new JnlpFileHandler(config.getServletContext(), _log);
	_jarDiffHandler = new JarDiffHandler(config.getServletContext(), _log);
	_resourceCatalog = new ResourceCatalog(config.getServletContext(), _log);		
    }
    
    public static synchronized ResourceBundle getResourceBundle() {
	if (_resourceBundle == null) {
	    _resourceBundle = ResourceBundle.getBundle("jnlp/sample/servlet/resources/strings");
	}
	return _resourceBundle;
    }
    
    
    /** We handle get requests too - eventhough the spec. only requeres POST requests */
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        handleRequest(request, response);
    }
    
    private void handleRequest(HttpServletRequest request, HttpServletResponse response) throws IOException {
	String requestStr = request.getRequestURI();
	if (request.getQueryString() != null) requestStr += "?" + request.getQueryString().trim();
	
	// Parse HTTP request
	DownloadRequest dreq = new DownloadRequest(getServletContext(), request);		
	if (_log.isInformationalLevel()) {
	    _log.addInformational("servlet.log.info.request",   requestStr);
	    _log.addInformational("servlet.log.info.useragent", request.getHeader("User-Agent"));	    
	}
	if (_log.isDebugLevel()) {
	    _log.addDebug(dreq.toString());
	}
	
	// Check if it is a valid request
	try { 
	    // Check if the request is valid
	    validateRequest(dreq);
	    
	    // Decide what resource to return
	    JnlpResource jnlpres = locateResource(dreq);	    
	    _log.addDebug("JnlpResource: " + jnlpres);
	    
	    
	    if (_log.isInformationalLevel()) {
		_log.addInformational("servlet.log.info.goodrequest", jnlpres.getPath());		
	    }
	    
	    // Return selected resource
	    DownloadResponse dres = constructResponse(jnlpres, dreq);	    
	    
	    dres.sendRespond(response);
	    
	} catch(ErrorResponseException ere) {
	    if (_log.isInformationalLevel()) {	    
		_log.addInformational("servlet.log.info.badrequest", requestStr);
	    }
	    if (_log.isDebugLevel()) {
		_log.addDebug("Response: "+ ere.toString());
	    }
	    // Return response from exception
	    ere.getDownloadResponse().sendRespond(response);
	} catch(Throwable e) {
	    _log.addFatal("servlet.log.fatal.internalerror", e);
	    response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
	}
    }
    
    /** Make sure that it is a valid request. This is also the place to implement the
     *  reverse IP lookup
     */
    private void validateRequest(DownloadRequest dreq) throws ErrorResponseException {
	String path = dreq.getPath();
	if (path.endsWith(ResourceCatalog.VERSION_XML_FILENAME) ||
	    path.indexOf("__") != -1 ) {
	    throw new ErrorResponseException(DownloadResponse.getNoContentResponse());	
        }
    }
    
    /** Interprets the download request and convert it into a resource that is
     *  part of the Web Archive.
     */
    private JnlpResource locateResource(DownloadRequest dreq) throws IOException, ErrorResponseException {    
	if (dreq.getVersion() == null) {	   
	    return handleBasicDownload(dreq);	
	} else {
	    return handleVersionRequest(dreq);
	}	
    }
    
    private JnlpResource handleBasicDownload(DownloadRequest dreq) throws ErrorResponseException, IOException {
	_log.addDebug("Basic Protocol lookup");
	// Do not return directory names for basic protocol
	if (dreq.getPath() == null || dreq.getPath().endsWith("/")) {
	    throw new ErrorResponseException(DownloadResponse.getNoContentResponse());
	}
	// Lookup resource	
	JnlpResource jnlpres = new JnlpResource(getServletContext(), dreq.getPath());
	if (!jnlpres.exists()) {		    
	    throw new ErrorResponseException(DownloadResponse.getNoContentResponse());
	}			
	return jnlpres;
    }        
    
    private JnlpResource handleVersionRequest(DownloadRequest dreq) throws IOException, ErrorResponseException {	
	_log.addDebug("Version-based/Extension based lookup");
	return _resourceCatalog.lookupResource(dreq);	
    }
    
    /** Given a DownloadPath and a DownloadRequest, it constructs the data stream to return
     *  to the requester
     */
    private DownloadResponse constructResponse(JnlpResource jnlpres, DownloadRequest dreq) throws IOException {
	String path = jnlpres.getPath();			
	if (jnlpres.isJnlpFile()) {	    
	    // It is a JNLP file. It need to be macro-expanded, so it is handled differently
	    boolean supportQuery = !JarDiffHandler.isJavawsVersion(dreq, "1.0 1.0.1 1.2 1.4.2");
	    _log.addDebug("SupportQuery in Href: " + supportQuery);

	    // only support query string in href for 1.5 and above
	    if (supportQuery) {
		return _jnlpFileHandler.getJnlpFileEx(jnlpres, dreq);
	    } else {
		return _jnlpFileHandler.getJnlpFile(jnlpres, dreq);
	    }
	} 
	
	// Check if a JARDiff can be returned
	if (dreq.getCurrentVersionId() != null && jnlpres.isJarFile()) {	    
	    DownloadResponse response = _jarDiffHandler.getJarDiffEntry(_resourceCatalog, dreq, jnlpres);
	    if (response != null) {
		_log.addInformational("servlet.log.info.jardiff.response");
		return response;	    
	    }
	}
	
	// Return WAR file resource
	return DownloadResponse.getFileDownloadResponse(jnlpres.getResource(), 
							jnlpres.getMimeType(), 
							jnlpres.getLastModified(), 
							jnlpres.getReturnVersionId());	    	
    }
}