ThreadSafeClientConnManager用来支持多线程的使用http client

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager;
import org.apache.http.protocol.BasicHttpContext;
import org.apache.http.protocol.HttpContext;
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 an HttpClient with the ThreadSafeClientConnManager.
        // This connection manager must be used if more than one thread will
        // be using the HttpClient.
        ThreadSafeClientConnManager cm = new ThreadSafeClientConnManager();
        cm.setMaxTotal(100);

        HttpClient httpclient = new DefaultHttpClient(cm);
        try {
            // create an array of URIs to perform GETs on
            String[] urisToGet = {
                "http://hc.apache.org/",
                "http://hc.apache.org/httpcomponents-core-ga/",
                "http://hc.apache.org/httpcomponents-client-ga/",
                "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();
            }

        } finally {
            // 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);
            }
        }

    }

}