Java tutorial
/* * $HeadURL: https://svn.apache.org/repos/asf/httpcomponents/httpcore/tags/4.0.1/httpcore-nio/src/examples/org/apache/http/examples/nio/NHttpClient.java $ * $Revision: 744516 $ * $Date: 2009-02-14 17:38:14 +0100 (Sat, 14 Feb 2009) $ * * ==================================================================== * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * */ //package org.apache.http.examples.nio; import java.io.IOException; import java.io.InterruptedIOException; import java.net.InetSocketAddress; import java.util.concurrent.CountDownLatch; import org.apache.http.HttpEntity; import org.apache.http.HttpException; import org.apache.http.HttpHost; import org.apache.http.HttpRequest; import org.apache.http.HttpResponse; import org.apache.http.impl.DefaultConnectionReuseStrategy; import org.apache.http.params.BasicHttpParams; import org.apache.http.impl.nio.DefaultClientIOEventDispatch; import org.apache.http.impl.nio.reactor.DefaultConnectingIOReactor; import org.apache.http.message.BasicHttpRequest; import org.apache.http.nio.NHttpConnection; import org.apache.http.nio.protocol.BufferingHttpClientHandler; import org.apache.http.nio.protocol.EventListener; import org.apache.http.nio.protocol.HttpRequestExecutionHandler; import org.apache.http.nio.reactor.ConnectingIOReactor; import org.apache.http.nio.reactor.IOEventDispatch; import org.apache.http.nio.reactor.SessionRequest; import org.apache.http.nio.reactor.SessionRequestCallback; import org.apache.http.params.CoreConnectionPNames; import org.apache.http.params.HttpParams; import org.apache.http.params.CoreProtocolPNames; import org.apache.http.protocol.BasicHttpProcessor; import org.apache.http.protocol.HttpContext; import org.apache.http.protocol.ExecutionContext; import org.apache.http.protocol.RequestConnControl; import org.apache.http.protocol.RequestContent; import org.apache.http.protocol.RequestExpectContinue; import org.apache.http.protocol.RequestTargetHost; import org.apache.http.protocol.RequestUserAgent; import org.apache.http.util.EntityUtils; /** * Elemental example for executing HTTP requests using the non-blocking I/O model. * <p> * Please note the purpose of this application is demonstrate the usage of HttpCore APIs. * It is NOT intended to demonstrate the most efficient way of building an HTTP client. * * * @version $Revision: 744516 $ */ public class NHttpClient { public static void main(String[] args) throws Exception { HttpParams params = new BasicHttpParams(); params.setIntParameter(CoreConnectionPNames.SO_TIMEOUT, 5000) .setIntParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, 10000) .setIntParameter(CoreConnectionPNames.SOCKET_BUFFER_SIZE, 8 * 1024) .setBooleanParameter(CoreConnectionPNames.STALE_CONNECTION_CHECK, false) .setBooleanParameter(CoreConnectionPNames.TCP_NODELAY, true) .setParameter(CoreProtocolPNames.USER_AGENT, "HttpComponents/1.1"); final ConnectingIOReactor ioReactor = new DefaultConnectingIOReactor(2, params); BasicHttpProcessor httpproc = new BasicHttpProcessor(); httpproc.addInterceptor(new RequestContent()); httpproc.addInterceptor(new RequestTargetHost()); httpproc.addInterceptor(new RequestConnControl()); httpproc.addInterceptor(new RequestUserAgent()); httpproc.addInterceptor(new RequestExpectContinue()); // We are going to use this object to synchronize between the // I/O event and main threads CountDownLatch requestCount = new CountDownLatch(3); BufferingHttpClientHandler handler = new BufferingHttpClientHandler(httpproc, new MyHttpRequestExecutionHandler(requestCount), new DefaultConnectionReuseStrategy(), params); handler.setEventListener(new EventLogger()); final IOEventDispatch ioEventDispatch = new DefaultClientIOEventDispatch(handler, params); Thread t = new Thread(new Runnable() { public void run() { try { ioReactor.execute(ioEventDispatch); } catch (InterruptedIOException ex) { System.err.println("Interrupted"); } catch (IOException e) { System.err.println("I/O error: " + e.getMessage()); } System.out.println("Shutdown"); } }); t.start(); SessionRequest[] reqs = new SessionRequest[3]; reqs[0] = ioReactor.connect(new InetSocketAddress("www.yahoo.com", 80), null, new HttpHost("www.yahoo.com"), new MySessionRequestCallback(requestCount)); reqs[1] = ioReactor.connect(new InetSocketAddress("www.google.com", 80), null, new HttpHost("www.google.ch"), new MySessionRequestCallback(requestCount)); reqs[2] = ioReactor.connect(new InetSocketAddress("www.apache.org", 80), null, new HttpHost("www.apache.org"), new MySessionRequestCallback(requestCount)); // Block until all connections signal // completion of the request execution requestCount.await(); System.out.println("Shutting down I/O reactor"); ioReactor.shutdown(); System.out.println("Done"); } static class MyHttpRequestExecutionHandler implements HttpRequestExecutionHandler { private final static String REQUEST_SENT = "request-sent"; private final static String RESPONSE_RECEIVED = "response-received"; private final CountDownLatch requestCount; public MyHttpRequestExecutionHandler(final CountDownLatch requestCount) { super(); this.requestCount = requestCount; } public void initalizeContext(final HttpContext context, final Object attachment) { HttpHost targetHost = (HttpHost) attachment; context.setAttribute(ExecutionContext.HTTP_TARGET_HOST, targetHost); } public void finalizeContext(final HttpContext context) { Object flag = context.getAttribute(RESPONSE_RECEIVED); if (flag == null) { // Signal completion of the request execution requestCount.countDown(); } } public HttpRequest submitRequest(final HttpContext context) { HttpHost targetHost = (HttpHost) context.getAttribute(ExecutionContext.HTTP_TARGET_HOST); Object flag = context.getAttribute(REQUEST_SENT); if (flag == null) { // Stick some object into the context context.setAttribute(REQUEST_SENT, Boolean.TRUE); System.out.println("--------------"); System.out.println("Sending request to " + targetHost); System.out.println("--------------"); return new BasicHttpRequest("GET", "/"); } else { // No new request to submit return null; } } public void handleResponse(final HttpResponse response, final HttpContext context) { HttpEntity entity = response.getEntity(); try { String content = EntityUtils.toString(entity); System.out.println("--------------"); System.out.println(response.getStatusLine()); System.out.println("--------------"); System.out.println("Document length: " + content.length()); System.out.println("--------------"); } catch (IOException ex) { System.err.println("I/O error: " + ex.getMessage()); } context.setAttribute(RESPONSE_RECEIVED, Boolean.TRUE); // Signal completion of the request execution requestCount.countDown(); } } static class MySessionRequestCallback implements SessionRequestCallback { private final CountDownLatch requestCount; public MySessionRequestCallback(final CountDownLatch requestCount) { super(); this.requestCount = requestCount; } public void cancelled(final SessionRequest request) { System.out.println("Connect request cancelled: " + request.getRemoteAddress()); this.requestCount.countDown(); } public void completed(final SessionRequest request) { } public void failed(final SessionRequest request) { System.out.println("Connect request failed: " + request.getRemoteAddress()); this.requestCount.countDown(); } public void timeout(final SessionRequest request) { System.out.println("Connect request timed out: " + request.getRemoteAddress()); this.requestCount.countDown(); } } static class EventLogger implements EventListener { public void connectionOpen(final NHttpConnection conn) { System.out.println("Connection open: " + conn); } public void connectionTimeout(final NHttpConnection conn) { System.out.println("Connection timed out: " + conn); } public void connectionClosed(final NHttpConnection conn) { System.out.println("Connection closed: " + conn); } public void fatalIOException(final IOException ex, final NHttpConnection conn) { System.err.println("I/O error: " + ex.getMessage()); } public void fatalProtocolException(final HttpException ex, final NHttpConnection conn) { System.err.println("HTTP error: " + ex.getMessage()); } } }