httpclient5/src/test/java/org/apache/hc/client5/http/examples/ClientMultiThreadedExecution.java

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 * 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
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 * <http://www.apache.org/>.
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 */
package org.apache.hc.client5.http.examples;

import org.apache.hc.client5.http.classic.methods.HttpGet;
import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
import org.apache.hc.client5.http.impl.classic.HttpClients;
import org.apache.hc.client5.http.impl.io.PoolingHttpClientConnectionManager;
import org.apache.hc.core5.http.HttpEntity;
import org.apache.hc.core5.http.io.entity.EntityUtils;
import org.apache.hc.core5.http.protocol.BasicHttpContext;
import org.apache.hc.core5.http.protocol.HttpContext;

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

    public static void main(final String[] args) throws Exception {
        // Create an HttpClient with the PoolingHttpClientConnectionManager.
        // This connection manager must be used if more than one thread will
        // be using the HttpClient.
        final PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager();
        cm.setMaxTotal(100);

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

            // create a thread for each URI
            final GetThread[] threads = new GetThread[urisToGet.length];
            for (int i = 0; i < threads.length; i++) {
                final HttpGet httpget = new HttpGet(urisToGet[i]);
                threads[i] = new GetThread(httpclient, httpget, i + 1);
            }

            // start the threads
            for (final GetThread thread : threads) {
                thread.start();
            }

            // join the threads
            for (final GetThread thread : threads) {
                thread.join();
            }

        }
    }

    /**
     * A thread that performs a GET.
     */
    static class GetThread extends Thread {

        private final CloseableHttpClient httpClient;
        private final HttpContext context;
        private final HttpGet httpget;
        private final int id;

        public GetThread(final CloseableHttpClient httpClient, final HttpGet httpget, final 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() {
            try {
                System.out.println(id + " - about to get something from " + httpget.getUri());
                try (CloseableHttpResponse response = httpClient.execute(httpget, context)) {
                    System.out.println(id + " - get executed");
                    // get the response body as an array of bytes
                    final HttpEntity entity = response.getEntity();
                    if (entity != null) {
                        final byte[] bytes = EntityUtils.toByteArray(entity);
                        System.out.println(id + " - " + bytes.length + " bytes read");
                    }
                }
            } catch (final Exception e) {
                System.out.println(id + " - error: " + e);
            }
        }

    }

}