Java tutorial
package org.gnode.wda.server; /** * Copyright 2010 Kenneth Jorgensen (kennethjorgensen.com) (modifications) * - original code can be found at http://www.siafoo.net/snippet/258 * Copyright 2009 Stou Sandalski (Siafoo.net) * Copyright 1999-2008 The Apache Software Foundation * * 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. * */ import java.io.InputStream; import java.io.IOException; import java.io.OutputStream; import java.net.URI; import java.net.URISyntaxException; import java.util.Enumeration; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.ServletException; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpEntityEnclosingRequestBase; import org.apache.http.client.methods.HttpRequestBase; import org.apache.http.entity.InputStreamEntity; import org.apache.http.Header; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.StatusLine; /** * This servlet provides a proxy to other servers for use in development with GWT devmode. * It is not meant, in any way shape or form, to be used in production. */ public class ProxyServlet extends HttpServlet { /** * */ private static final long serialVersionUID = 1L; private static final String targetServer = "http://172.24.10.90"; @Override @SuppressWarnings("unchecked") protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // Create new client to perform the proxied request HttpClient httpclient = new DefaultHttpClient(); // Determine final URL StringBuffer uri = new StringBuffer(); uri.append(targetServer); // This is a very bad hack. In order to remove my proxy servlet-path, I have used a substring method. // Turns "/proxy/asdf" into "/asdf" uri.append(req.getRequestURI().substring(6)); // Add any supplied query strings String queryString = req.getQueryString(); if (queryString != null) { uri.append("?" + queryString); } // Get HTTP method final String method = req.getMethod(); // Create new HTTP request container HttpRequestBase request = null; // Get content length int contentLength = req.getContentLength(); // Unknown content length ... // if (contentLength == -1) // throw new ServletException("Cannot handle unknown content length"); // If we don't have an entity body, things are quite simple if (contentLength < 1) { request = new HttpRequestBase() { public String getMethod() { return method; } }; } else { // Prepare request HttpEntityEnclosingRequestBase tmpRequest = new HttpEntityEnclosingRequestBase() { public String getMethod() { return method; } }; // Transfer entity body from the received request to the new request InputStreamEntity entity = new InputStreamEntity(req.getInputStream(), contentLength); tmpRequest.setEntity(entity); request = tmpRequest; } // Set URI try { request.setURI(new URI(uri.toString())); } catch (URISyntaxException e) { throw new ServletException("URISyntaxException: " + e.getMessage()); } // Copy headers from old request to new request // @todo not sure how this handles multiple headers with the same name Enumeration<String> headers = req.getHeaderNames(); while (headers.hasMoreElements()) { String headerName = headers.nextElement(); String headerValue = req.getHeader(headerName); // Skip Content-Length and Host String lowerHeader = headerName.toLowerCase(); if (lowerHeader.equals("content-length") == false && lowerHeader.equals("host") == false) { // System.out.println(headerName.toLowerCase() + ": " + headerValue); request.addHeader(headerName, headerValue); } } // Execute the request HttpResponse response = httpclient.execute(request); // Transfer status code to the response StatusLine status = response.getStatusLine(); resp.setStatus(status.getStatusCode()); // resp.setStatus(status.getStatusCode(), status.getReasonPhrase()); // This seems to be deprecated. Yes status message is "ambigous", but I don't approve // Transfer headers to the response Header[] responseHeaders = response.getAllHeaders(); for (int i = 0; i < responseHeaders.length; i++) { Header header = responseHeaders[i]; resp.addHeader(header.getName(), header.getValue()); } // Transfer proxy response entity to the servlet response HttpEntity entity = response.getEntity(); if (entity == null) return; InputStream input = entity.getContent(); OutputStream output = resp.getOutputStream(); int b = input.read(); while (b != -1) { output.write(b); b = input.read(); } // Clean up input.close(); output.close(); httpclient.getConnectionManager().shutdown(); } }