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/>. * */ import java.io.IOException; import java.io.InterruptedIOException; import java.net.InetSocketAddress; import java.lang.Throwable; // MG-2009.07.06 Added for debugging. import java.net.URI; 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 $ */ // class Connection_Event_Logger 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()); // } // } public class NIO_HTTP_Client { ConnectingIOReactor io_reactor; IOEventDispatch io_event_dispatch; //public static HttpHost toHttpHost(Object x) {return (HttpHost)x;} // Coercion procedure for Scheme. public static void setTargetHost(final HttpContext context, String key, final Object x) { HttpHost target_host = (HttpHost) x; //System.err.println("inside setTargetHost"); context.setAttribute(key, target_host); //System.err.println("finished setTargetHost"); } // public void initalizeContext(final HttpContext context, final Object attachment) { // HttpHost targetHost = (HttpHost) attachment; // context.setAttribute(ExecutionContext.HTTP_TARGET_HOST, targetHost); // } public NIO_HTTP_Client(String user_agent, HttpRequestExecutionHandler request_handler, EventListener connection_listener) throws Exception { // Construct the long-lived HTTP parameters. HttpParams parameters = new BasicHttpParams(); parameters // Socket data timeout is 5,000 milliseconds (5 seconds). .setIntParameter(CoreConnectionPNames.SO_TIMEOUT, 5000) // Maximum time allowed for connection establishment is 10,00 milliseconds (10 seconds). .setIntParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, 10000) // Socket buffer size is 8 kB. .setIntParameter(CoreConnectionPNames.SOCKET_BUFFER_SIZE, 8 * 1024) // Don't bother to check for stale TCP connections. .setBooleanParameter(CoreConnectionPNames.STALE_CONNECTION_CHECK, false) // Don't use Nagle's algorithm (in other words minimize latency). .setBooleanParameter(CoreConnectionPNames.TCP_NODELAY, true) // Set the user agent string that the client sends to the server. .setParameter(CoreProtocolPNames.USER_AGENT, user_agent); // Construct the core HTTP request processor. BasicHttpProcessor http_processor = new BasicHttpProcessor(); // Add Content-Length header to request where appropriate. http_processor.addInterceptor(new RequestContent()); // Always include Host header in requests. http_processor.addInterceptor(new RequestTargetHost()); // Maintain connection keep-alive by default. http_processor.addInterceptor(new RequestConnControl()); // Include user agent information in each request. http_processor.addInterceptor(new RequestUserAgent()); // Allocate an HTTP client handler. BufferingHttpClientHandler client_handler = new BufferingHttpClientHandler(http_processor, // Basic HTTP Processor. request_handler, new DefaultConnectionReuseStrategy(), parameters); client_handler.setEventListener(connection_listener); // Use two worker threads for the IO reactor. io_reactor = new DefaultConnectingIOReactor(2, parameters); io_event_dispatch = new DefaultClientIOEventDispatch(client_handler, parameters); // t = new Thread(new Runnable() { // public void run() { // try { // io_reactor.execute(io_event_dispatch); // } catch (InterruptedIOException ex) { // System.err.println("Interrupted"); // } catch (IOException e) { // System.err.println("I/O error: " + e.getMessage()); // Throwable c = e.getCause(); // if (c != null) { // System.err.println("Cause: " + c.toString()); // }else { // System.err.println("Cause: unknown"); // } // } // System.out.println("Shutdown"); // } // }); // t.start(); } public void go() throws Exception { io_reactor.execute(io_event_dispatch); // All exceptions will be propagated to Scheme level. } // public void go() { // try { // io_reactor.execute(io_event_dispatch); // } catch (InterruptedIOException ex) { // System.err.println("Interrupted"); // } catch (IOException e) { // System.err.println("I/O error: " + e.getMessage()); // } // System.out.println("Shutdown"); // } // Start an HTTP session with endpoint host:port using the given session handler. public SessionRequest openSession(String host, int port, SessionRequestCallback session_handler) { return io_reactor.connect(new InetSocketAddress(host, port), null, new HttpHost(host, port), // HTTP host could be different. Change to accomodate for proxy. session_handler); } public static String uriForRequest(URI u) { if (null == u.getQuery()) { return u.getPath(); } else { int n = u.getPath().length() + u.getQuery().length() + 1; StringBuilder b = new StringBuilder(n); b.append(u.getPath()).append('?').append(u.getQuery()); return b.toString(); } } } // static class CREST_HTTP_Request_Execution_Handler implements HttpRequestExecutionHandler { // private final static String REQUEST_SENT = "request-sent"; // private final static String RESPONSE_RECEIVED = "response-received"; // public CREST_HTTP_Request_Execution_Handler() { // super(); // } // public void initializeContext(final HttpContext context, final Object attachment) { // HttpHost target_host = (HttpHost) attachment; // context.setAttribute(ExecutionContext.HTTP_TARGET_HOST, target_host); // } // public void finalizeContext(final HttpContext context) { // // This handler is called when connection closes. // } // public HttpRequest submitRequest(final HttpContext context) { // HttpHost target_host = (HttpHost) context.getAttribute(ExecutionContext.HTTP_TARGET_HOST); // 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(); // } // } // class CREST_Session_Request_Callback implements SessionRequestCallback { // public CREST_Session_Request_Callback() { // } // public void cancelled(final SessionRequest request) { // System.out.println("Connect request cancelled: " + request.getRemoteAddress()); // } // public void completed(final SessionRequest request) { // } // public void failed(final SessionRequest request) { // System.out.println("Connect request failed: " + request.getRemoteAddress()); // } // public void timeout(final SessionRequest request) { // System.out.println("Connect request timed out: " + request.getRemoteAddress()); // } // }