Java tutorial
/* * Copyright 2014 JBoss Inc * * 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 io.wittmann.jiralist.servlet; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.HttpURLConnection; import java.net.URL; import java.util.HashSet; import java.util.List; import java.util.Map; import java.util.Set; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.io.IOUtils; /** * A proxy servlet used to get around cross-origin problems when pulling * down content from remote sites. * * @author eric.wittmann@redhat.com */ @SuppressWarnings("nls") public class ProxyServlet extends HttpServlet { private static final long serialVersionUID = -4704803997251798191L; private static long requestCounter = 0; private static Set<String> EXCLUDE_HEADERS = new HashSet<String>(); static { EXCLUDE_HEADERS.add("ETag"); EXCLUDE_HEADERS.add("Last-Modified"); EXCLUDE_HEADERS.add("Date"); EXCLUDE_HEADERS.add("Cache-control"); EXCLUDE_HEADERS.add("Transfer-Encoding"); } /** * @see javax.servlet.http.HttpServlet#service(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse) */ @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { long requestId = requestCounter++; String proxyTo = "https://issues.jboss.org/rest/api/2"; if (req.getHeader("X-Proxy-To") != null) { proxyTo = req.getHeader("X-Proxy-To"); } String url = proxyTo + req.getPathInfo(); if (req.getQueryString() != null) { url += "?" + req.getQueryString(); } System.out.println("[" + requestId + "]: Proxying to: " + url); boolean isWrite = req.getMethod().equalsIgnoreCase("post") || req.getMethod().equalsIgnoreCase("put"); URL remoteUrl = new URL(url); HttpURLConnection remoteConn = (HttpURLConnection) remoteUrl.openConnection(); if (isWrite) { remoteConn.setDoOutput(true); } remoteConn.setRequestMethod(req.getMethod()); String auth = req.getHeader("Authorization"); if (auth != null) { remoteConn.setRequestProperty("Authorization", auth); } String ct = req.getHeader("Content-Type"); if (ct != null) { remoteConn.setRequestProperty("Content-Type", ct); } String cl = req.getHeader("Content-Length"); if (cl != null) { remoteConn.setRequestProperty("Content-Length", cl); } String accept = req.getHeader("Accept"); if (accept != null) { remoteConn.setRequestProperty("Accept", accept); } System.out.println("[" + requestId + "]: Request Info:"); System.out.println("[" + requestId + "]: Method: " + req.getMethod()); System.out.println("[" + requestId + "]: Has auth: " + (auth != null)); System.out.println("[" + requestId + "]: Content-Type: " + ct); System.out.println("[" + requestId + "]: Content-Length: " + cl); if (isWrite) { InputStream requestIS = null; OutputStream remoteOS = null; try { requestIS = req.getInputStream(); remoteOS = remoteConn.getOutputStream(); IOUtils.copy(requestIS, remoteOS); remoteOS.flush(); } catch (Exception e) { e.printStackTrace(); resp.sendError(500, e.getMessage()); return; } finally { IOUtils.closeQuietly(requestIS); IOUtils.closeQuietly(remoteOS); } } InputStream remoteIS = null; OutputStream responseOS = null; int responseCode = remoteConn.getResponseCode(); System.out.println("[" + requestId + "]: Response Info:"); System.out.println("[" + requestId + "]: Code: " + responseCode); if (responseCode == 400) { remoteIS = remoteConn.getInputStream(); responseOS = System.out; IOUtils.copy(remoteIS, responseOS); IOUtils.closeQuietly(remoteIS); resp.sendError(400, "Error 400"); } else { try { Map<String, List<String>> headerFields = remoteConn.getHeaderFields(); for (String headerName : headerFields.keySet()) { if (headerName == null) { continue; } if (EXCLUDE_HEADERS.contains(headerName)) { continue; } String headerValue = remoteConn.getHeaderField(headerName); resp.setHeader(headerName, headerValue); System.out.println("[" + requestId + "]: " + headerName + " : " + headerValue); } resp.setHeader("Cache-control", "no-cache, no-store, must-revalidate"); //$NON-NLS-2$ remoteIS = remoteConn.getInputStream(); responseOS = resp.getOutputStream(); int bytesCopied = IOUtils.copy(remoteIS, responseOS); System.out.println("[" + requestId + "]: Bytes Proxied: " + bytesCopied); resp.flushBuffer(); } catch (Exception e) { e.printStackTrace(); resp.sendError(500, e.getMessage()); } finally { IOUtils.closeQuietly(responseOS); IOUtils.closeQuietly(remoteIS); } } } }