This is an example that performs GETs from multiple threads.

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import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.MultiThreadedHttpConnectionManager;
import org.apache.commons.httpclient.methods.GetMethod;

/**
 * An example that performs GETs from multiple threads.
 *
 * @author Michael Becke
 */
public class MultiThreadedExample {
    
    /**
     * Constructor for MultiThreadedExample.
     */
    public MultiThreadedExample() {
        super();
    }
    
    public static void main(String[] args) {
        
        // Create an HttpClient with the MultiThreadedHttpConnectionManager.
        // This connection manager must be used if more than one thread will
        // be using the HttpClient.
        HttpClient httpClient = new HttpClient(
                new MultiThreadedHttpConnectionManager());
        
        // Set the default host/protocol for the methods to connect to.
        // This value will only be used if the methods are not given 
        // an absolute URI
        httpClient.getHostConfiguration().setHost(
                "jakarta.apache.org", 80, "http");
        
        // create an array of URIs to perform GETs on
        String[] urisToGet = {
            "/",
            "/commons/",
            "/commons/httpclient/",
            "http://cvs.apache.org/viewcvs.cgi/jakarta-commons/httpclient/"
        };
        
        // create a thread for each URI
        GetThread[] threads = new GetThread[urisToGet.length];
        
        for (int i = 0; i < threads.length; i++) {
            GetMethod get = new GetMethod(urisToGet[i]);
            get.setFollowRedirects(true);
            threads[i] = new GetThread(httpClient, get, i + 1);
        }
        
        // start the threads
        for (int j = 0; j < threads.length; j++) {
            threads[j].start();
        }
        
    }
    
    /**
     * A thread that performs a GET.
     */
    static class GetThread extends Thread {
        
        private HttpClient httpClient;
        private GetMethod method;
        private int id;
        
        public GetThread(HttpClient httpClient, GetMethod method, 
                int id) {
            
            this.httpClient = httpClient;
            this.method = method;
            this.id = id;
            
        }
        
        /**
         * Executes the GetMethod and prints some satus information.
         */
        public void run() {
            
            try {
                
                System.out.println(id + 
                        " - about to get something from " + 
                        method.getURI());
                
                // execute the method
                httpClient.executeMethod(method);
                
                System.out.println(id + " - get executed");
                
                // get the response body as an array of bytes
                byte[] bytes = method.getResponseBody();
                
                System.out.println(id + " - " + bytes.length + 
                        " bytes read");
                
            } catch (Exception e) {
                System.out.println(id + " - error: " + e);
            } finally {
                // always release the connection after we're done
                method.releaseConnection();
                System.out.println(id + " - connection released");
            }
        }
        
    }
    
}

Source: Apache HttpClient