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Java example source code file (ClientMultiThreadedExecution.java)

This example source code file (ClientMultiThreadedExecution.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java tags/keywords

basichttpcontext, basichttpparams, clientconnectionmanager, exception, getthread, httpclient, httpcontext, httpentity, httpget, httpresponse, override, schemeregistry, string, threadsafeclientconnmanager

The ClientMultiThreadedExecution.java example source code

/*
 * ====================================================================
 *
 *  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.client;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpVersion;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.conn.ClientConnectionManager;
import org.apache.http.conn.params.ConnManagerParams;
import org.apache.http.conn.scheme.PlainSocketFactory;
import org.apache.http.conn.scheme.Scheme;
import org.apache.http.conn.scheme.SchemeRegistry;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpParams;
import org.apache.http.params.HttpProtocolParams;
import org.apache.http.protocol.HttpContext;
import org.apache.http.protocol.BasicHttpContext;
import org.apache.http.util.EntityUtils;

/**
 * An example that performs GETs from multiple threads.
 * 
 */
public class ClientMultiThreadedExecution {

    public static void main(String[] args) throws Exception {
        // Create and initialize HTTP parameters
        HttpParams params = new BasicHttpParams();
        ConnManagerParams.setMaxTotalConnections(params, 100);
        HttpProtocolParams.setVersion(params, HttpVersion.HTTP_1_1);
        
        // Create and initialize scheme registry 
        SchemeRegistry schemeRegistry = new SchemeRegistry();
        schemeRegistry.register(
                new Scheme("http", PlainSocketFactory.getSocketFactory(), 80));
        
        // Create an HttpClient with the ThreadSafeClientConnManager.
        // This connection manager must be used if more than one thread will
        // be using the HttpClient.
        ClientConnectionManager cm = new ThreadSafeClientConnManager(params, schemeRegistry);
        HttpClient httpClient = new DefaultHttpClient(cm, params);
        
        // create an array of URIs to perform GETs on
        String[] urisToGet = {
            "http://hc.apache.org/",
            "http://hc.apache.org/httpcomponents-core/",
            "http://hc.apache.org/httpcomponents-client/",
            "http://svn.apache.org/viewvc/httpcomponents/"
        };
        
        // create a thread for each URI
        GetThread[] threads = new GetThread[urisToGet.length];
        for (int i = 0; i < threads.length; i++) {
            HttpGet httpget = new HttpGet(urisToGet[i]);
            threads[i] = new GetThread(httpClient, httpget, i + 1);
        }
        
        // start the threads
        for (int j = 0; j < threads.length; j++) {
            threads[j].start();
        }
        
        // join the threads
        for (int j = 0; j < threads.length; j++) {
            threads[j].join();
        }

        // When HttpClient instance is no longer needed, 
        // shut down the connection manager to ensure
        // immediate deallocation of all system resources
        httpClient.getConnectionManager().shutdown();        
    }
    
    /**
     * A thread that performs a GET.
     */
    static class GetThread extends Thread {
        
        private final HttpClient httpClient;
        private final HttpContext context;
        private final HttpGet httpget;
        private final int id;
        
        public GetThread(HttpClient httpClient, HttpGet httpget, int id) {
            this.httpClient = httpClient;
            this.context = new BasicHttpContext();
            this.httpget = httpget;
            this.id = id;
        }
        
        /**
         * Executes the GetMethod and prints some status information.
         */
        @Override
        public void run() {
            
            System.out.println(id + " - about to get something from " + httpget.getURI());

            try {
                
                // execute the method
                HttpResponse response = httpClient.execute(httpget, context);
                
                System.out.println(id + " - get executed");
                // get the response body as an array of bytes
                HttpEntity entity = response.getEntity();
                if (entity != null) {
                    byte[] bytes = EntityUtils.toByteArray(entity);
                    System.out.println(id + " - " + bytes.length + " bytes read");
                }
                
            } catch (Exception e) {
                httpget.abort();
                System.out.println(id + " - error: " + e);
            }
        }
       
    }
    
}

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