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通过17个demo快速掌握apache httpclient(二),Manual connection release

此示例演示如何在HTTP响应的手动处理的情况下确保将底层HTTP连接释放回连接管理器。

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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.
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 * This software consists of voluntary contributions made by many
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 * <http://www.apache.org/>.
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package org.apache.http.examples.client;

import java.io.IOException;
import java.io.InputStream;

import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

/**
 * This example demonstrates the recommended way of using API to make sure
 * the underlying connection gets released back to the connection manager.
 */
public class ClientConnectionRelease {

    public final static void main(String[] args) throws Exception {
        CloseableHttpClient httpclient = HttpClients.createDefault();
        try {
            HttpGet httpget = new HttpGet("http://httpbin.org/get");

            System.out.println("Executing request " + httpget.getRequestLine());
            CloseableHttpResponse response = httpclient.execute(httpget);
            try {
                System.out.println("----------------------------------------");
                System.out.println(response.getStatusLine());

                // Get hold of the response entity
                HttpEntity entity = response.getEntity();

                // If the response does not enclose an entity, there is no need
                // to bother about connection release
                if (entity != null) {
                    InputStream instream = entity.getContent();
                    try {
                        instream.read();
                        // do something useful with the response
                    } catch (IOException ex) {
                        // In case of an IOException the connection will be released
                        // back to the connection manager automatically
                        throw ex;
                    } finally {
                        // Closing the input stream will trigger connection release
                        instream.close();
                    }
                }
            } finally {
                response.close();
            }
        } finally {
            httpclient.close();
        }
    }

}