httpclient 3 連接池

在項目期初是用HttpConnection，近期爲了用應對大促問題，大家決定將請求外部地圖接口改爲httpclient連接池。期初是朝着httpclient4.X準備的，結果在開發過程中，發現項目中引入的是httpClient3.2。多方找資料，發現3.X的資料已經相當少，特記錄一下。

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.MultiThreadedHttpConnectionManager;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.params.HttpConnectionManagerParams;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;

/**
 * 單例連接池
 *
 */
public class HttpClientPool {

    private static final Logger LOGGER = LoggerFactory.getLogger(HttpClientPool.class);

    private static volatile HttpClientPool pool;

    private MultiThreadedHttpConnectionManager connectionManager;

    private HttpClientPool(){
        connectionManager = new MultiThreadedHttpConnectionManager();

        HttpConnectionManagerParams params = new HttpConnectionManagerParams();//連接池屬性實例
        params.setDefaultMaxConnectionsPerHost(100);//每個網址最大連接數
        params.setMaxTotalConnections(100);//最大連接數
        params.setConnectionTimeout(1000);//連接超時時間
        params.setSoTimeout(2000);//獲取數據超時時間

        connectionManager.setParams(params);
    }

    public static HttpClientPool getInstance(){
        if(null == pool){
            LOGGER.info("外層判斷實例不存在，進行鎖定，鎖定線程{}",Thread.currentThread().getName());
            synchronized (HttpClientPool.class){
                if(null == pool){
                    LOGGER.info("內層判斷實例不存在，進行創建線程池，創建線程{}",Thread.currentThread().getName());
                    pool = new HttpClientPool();
                }
            }
        }
        return pool;
    }

    /**
     * 執行get方法，並將返回信息以字符串返回-不允許有留或文件操作
     * @param url
     * @return
     * @throws IOException
     */
    public String exeGetMethod(String url) {
        LOGGER.info("通過HttpClient請求路徑：{}",url);
        GetMethod getMethod = null;
       try {
           HttpClient client = new HttpClient(this.connectionManager);//創建客戶端，並交由連接池管理
           getMethod = new GetMethod(url);
           int statusCode = client.executeMethod(getMethod);
           if(200 == statusCode){
               return getMethod.getResponseBodyAsString();
           }else {
               LOGGER.info("獲取網絡信息失敗,url:{},返回碼：{}",url,statusCode);
               throw new RuntimeException("獲取網絡信息失敗,url:" + url + ",返回碼：" + statusCode);
           }
       } catch (Exception e){
           LOGGER.error("調用httpclient異常：",e);
           throw new RuntimeException("調用HttpClient異常！");
       } finally {
           if(null != getMethod){
               getMethod.releaseConnection();//釋放連接
           }
       }

    }
}

HttpClient 3.X連接池注意事項：
1. 創建MultiThreadedHttpConnectionManager對象
2. client屬性設置通過HttpConnectionManagerParams對象，如最大連接數、超時時間等。
3. 創建HttpClient對象需要傳入創建MultiThreadedHttpConnectionManager對象，這樣創建的client對象是交由連接池管理的
4. 調用結束後，需要將連接釋放。getMethod.releaseConnection();