GWT Proxy Servlet

  1package my.package;
  2
  3/**
  4 *    Copyright 2009 Stou Sandalski (Siafoo.net)
  5 *    Copyright 1999-2008 The Apache Software Foundation
  6 *
  7 *  Licensed under the Apache License, Version 2.0 (the "License");
  8 *  you may not use this file except in compliance with the License.
  9 *  You may obtain a copy of the License at
 10 *
 11 *      http://www.apache.org/licenses/LICENSE-2.0
 12 *
 13 *  Unless required by applicable law or agreed to in writing, software
 14 *  distributed under the License is distributed on an "AS IS" BASIS,
 15 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 16 *  See the License for the specific language governing permissions and
 17 *  limitations under the License.
 18 * 
 19 */
 20
 21import java.io.IOException;
 22import java.io.InputStream;
 23import java.io.OutputStream;
 24import java.util.Enumeration;
 25
 26import javax.servlet.ServletException;
 27import javax.servlet.http.HttpServlet;
 28import javax.servlet.http.HttpServletRequest;
 29import javax.servlet.http.HttpServletResponse;
 30import java.io.BufferedReader;
 31import java.io.BufferedWriter;
 32import java.io.InputStreamReader;
 33import java.io.OutputStreamWriter;
 34import java.util.ArrayList;
 35import java.util.List;
 36
 37import org.apache.http.HttpEntity;
 38import org.apache.http.HttpResponse;
 39import org.apache.http.NameValuePair;
 40import org.apache.http.client.HttpClient;
 41import org.apache.http.client.entity.UrlEncodedFormEntity;
 42import org.apache.http.client.methods.HttpGet;
 43import org.apache.http.client.methods.HttpPost;
 44import org.apache.http.client.methods.HttpRequestBase;
 45import org.apache.http.impl.client.DefaultHttpClient;
 46import org.apache.http.message.BasicNameValuePair;
 47import org.apache.http.protocol.HTTP;
 48
 49public class ProxyServlet extends HttpServlet {
 50
 51    /**
 52     * 
 53     */
 54    private static final long serialVersionUID = 8L;
 55
 56    private static final String targetServer = "http://localhost:5000";
 57    
 58    @Override
 59    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
 60        handleRequest(req, resp, false);
 61    }
 62    
 63    @Override
 64    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
 65        handleRequest(req, resp, true);
 66    }
 67    
 68    @SuppressWarnings("unchecked")
 69    protected void handleRequest(HttpServletRequest req, HttpServletResponse resp, boolean isPost) throws ServletException, IOException {
 70
 71        HttpClient httpclient = new DefaultHttpClient();
 72        
 73        StringBuffer sb = new StringBuffer();
 74        
 75        sb.append(targetServer);
 76        sb.append(req.getRequestURI());
 77        
 78        if(req.getQueryString() != null){
 79            sb.append("?" + req.getQueryString());
 80        }
 81
 82        HttpRequestBase targetRequest = null;
 83        
 84        if(isPost){
 85            System.out.println("POST");
 86            HttpPost post = new HttpPost(sb.toString());
 87            
 88            Enumeration<String> paramNames = req.getParameterNames();
 89
 90            String paramName = null;
 91            
 92            List <NameValuePair> params = new ArrayList <NameValuePair>();
 93            
 94            while(paramNames.hasMoreElements()){
 95                paramName = paramNames.nextElement();
 96                params.add(new BasicNameValuePair(paramName, req.getParameterValues(paramName)[0]));
 97            }
 98            
 99            post.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
100            targetRequest = post;
101        }else{
102            System.out.println("GET");
103            
104            HttpGet get = new HttpGet(sb.toString());
105            targetRequest = get;
106        }
107
108//        // This copies the headers but I never really cared to get it to work properly
109//        System.out.println("Request Headers");
110//        Enumeration<String> headerNames = req.getHeaderNames();
111//        String headerName = null;
112//        while(headerNames.hasMoreElements()){
113//            headerName = headerNames.nextElement();
114//            targetRequest.addHeader(headerName, req.getHeader(headerName));
115//            System.out.println(headerName + " : " + req.getHeader(headerName));
116//        }
117
118        HttpResponse targetResponse = httpclient.execute(targetRequest);
119        HttpEntity entity = targetResponse.getEntity();
120        
121        // Send the Response
122        InputStream input = entity.getContent();
123        OutputStream output = resp.getOutputStream();
124        
125        BufferedReader reader = new BufferedReader(new InputStreamReader(input));
126        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(output));
127        String line = reader.readLine();
128        
129        while(line != null){
130            writer.write(line + "\n");
131            line = reader.readLine();
132        }
133
134        reader.close();
135        writer.close();
136        httpclient.getConnectionManager().shutdown();
137    }
138    
139}