Java tutorial
/* * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. * * Copyright 2007-2008 Sun Microsystems, Inc. All rights reserved. * * The contents of this file are subject to the terms of either the GNU * General Public License Version 2 only ("GPL") or the Common Development * and Distribution License("CDDL") (collectively, the "License"). You * may not use this file except in compliance with the License. You can obtain * a copy of the License at https://socialsite.dev.java.net/legal/CDDL+GPL.html * or legal/LICENSE.txt. See the License for the specific language governing * permissions and limitations under the License. * * When distributing the software, include this License Header Notice in each * file and include the License file at legal/LICENSE.txt. Sun designates this * particular file as subject to the "Classpath" exception as provided by Sun * in the GPL Version 2 section of the License file that accompanied this code. * If applicable, add the following below the License Header, with the fields * enclosed by brackets [] replaced by your own identifying information: * "Portions Copyrighted [year] [name of copyright owner]" * * Contributor(s): * * If you wish your version of this file to be governed by only the CDDL or * only the GPL Version 2, indicate your decision by adding "[Contributor] * elects to include this software in this distribution under the [CDDL or GPL * Version 2] license." If you don't indicate a single choice of license, a * recipient has the option to distribute your version of this file under * either the CDDL, the GPL Version 2 or to extend the choice of license to * its licensees as provided above. However, if you add GPL Version 2 code * and therefore, elected the GPL Version 2 license, then the option applies * only if the new code is made subject to such option by the copyright * holder. */ package com.sun.socialsite.web.rest.servlets; import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.InputStream; import java.io.IOException; import java.io.OutputStream; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; import java.util.Enumeration; import java.util.HashSet; import java.util.List; import java.util.Map; import java.util.Set; import javax.net.ssl.HostnameVerifier; import javax.net.ssl.HttpsURLConnection; import javax.net.ssl.SSLSession; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; /** * Proxies requests to some other URL. */ public class ProxyServlet extends HttpServlet { private static final long serialVersionUID = 0L; private static Log log = LogFactory.getLog(ProxyServlet.class); private static final Set<String> unproxiedHeaders = new HashSet<String>(); static { // Be sure all entries are lowercase unproxiedHeaders.add("connection"); unproxiedHeaders.add("cookie"); unproxiedHeaders.add("host"); unproxiedHeaders.add("keep-alive"); unproxiedHeaders.add("user-agent"); } /** * Public constructor. */ public ProxyServlet() { } /** * Handles the HTTP <code>GET</code> method. * @param req servlet request * @param resp servlet response */ @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { try { URL url = getURL(req, req.getParameter("uri")); HttpURLConnection con = (HttpURLConnection) (url.openConnection()); con.setAllowUserInteraction(false); con.setUseCaches(false); // TODO: figure out why this is necessary for HTTPS URLs if (con instanceof HttpsURLConnection) { HostnameVerifier hv = new HostnameVerifier() { public boolean verify(String urlHostName, SSLSession session) { if ("localhost".equals(urlHostName) && "127.0.0.1".equals(session.getPeerHost())) { return true; } else { log.error("URL Host: " + urlHostName + " vs. " + session.getPeerHost()); return false; } } }; ((HttpsURLConnection) con).setDefaultHostnameVerifier(hv); } // pass along all appropriate HTTP headers Enumeration headerNames = req.getHeaderNames(); while (headerNames.hasMoreElements()) { String hname = (String) headerNames.nextElement(); if (!unproxiedHeaders.contains(hname.toLowerCase())) { con.addRequestProperty(hname, req.getHeader(hname)); } } con.connect(); // read result headers of GET, write to response Map<String, List<String>> headers = con.getHeaderFields(); for (String key : headers.keySet()) { if (key != null) { // TODO: why is this check necessary! List<String> header = headers.get(key); if (header.size() > 0) resp.setHeader(key, header.get(0)); } } InputStream in = con.getInputStream(); OutputStream out = resp.getOutputStream(); final byte[] buf = new byte[8192]; int len; while ((len = in.read(buf)) != -1) { out.write(buf, 0, len); } out.flush(); } catch (Exception e) { throw new ServletException(e); } } /** * Handles the HTTP <code>POST</code> method. * @param req servlet request * @param resp servlet response */ @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { URL url = getURL(req, req.getParameter("uri")); HttpURLConnection con = (HttpURLConnection) (url.openConnection()); con.setDoOutput(true); con.setAllowUserInteraction(false); con.setUseCaches(false); // TODO: figure out why this is necessary for HTTPS URLs if (con instanceof HttpsURLConnection) { HostnameVerifier hv = new HostnameVerifier() { public boolean verify(String urlHostName, SSLSession session) { if ("localhost".equals(urlHostName) && "127.0.0.1".equals(session.getPeerHost())) { return true; } else { log.error("URL Host: " + urlHostName + " vs. " + session.getPeerHost()); return false; } } }; ((HttpsURLConnection) con).setDefaultHostnameVerifier(hv); } // pass along all appropriate HTTP headers Enumeration headerNames = req.getHeaderNames(); while (headerNames.hasMoreElements()) { String hname = (String) headerNames.nextElement(); if (!unproxiedHeaders.contains(hname.toLowerCase())) { con.addRequestProperty(hname, req.getHeader(hname)); } } con.connect(); // read POST data from incoming request, write to outgoing request BufferedInputStream in = new BufferedInputStream(req.getInputStream()); BufferedOutputStream out = new BufferedOutputStream(con.getOutputStream()); byte buffer[] = new byte[8192]; for (int count = 0; count != -1;) { count = in.read(buffer, 0, 8192); if (count != -1) out.write(buffer, 0, count); } in.close(); out.close(); out.flush(); // read result headers of POST, write to response Map<String, List<String>> headers = con.getHeaderFields(); for (String key : headers.keySet()) { if (key != null) { // TODO: why is this check necessary! List<String> header = headers.get(key); if (header.size() > 0) resp.setHeader(key, header.get(0)); } } // read result data of POST, write out to response in = new BufferedInputStream(con.getInputStream()); out = new BufferedOutputStream(resp.getOutputStream()); for (int count = 0; count != -1;) { count = in.read(buffer, 0, 8192); if (count != -1) out.write(buffer, 0, count); } in.close(); out.close(); out.flush(); con.disconnect(); } private URL getURL(HttpServletRequest req, String uriString) throws MalformedURLException { String s = uriString.toLowerCase(); if ((s.startsWith("http://")) || (s.startsWith("https://"))) { return new URL(uriString); } else if (s.startsWith("/")) { return new URL(req.getScheme(), req.getServerName(), req.getServerPort(), uriString); } else { return new URL(req.getScheme(), req.getServerName(), req.getServerPort(), (req.getContextPath() + "/" + uriString)); } } }