httpclient连接池注意事项

ゝ一世哀愁。 2021-12-01 23:34 656阅读 0赞

**目录**

实例

参数

配置重要参数

导致问题

源码

正确的事例

httpclient官网

--------------------

使用MultiThreadedHttpConnectionManager来配置线程池连接数量等等。

# 实例 #

MultiThreadedHttpConnectionManager connectionManager = 
          		new MultiThreadedHttpConnectionManager（）; 
          	HttpClient客户端=新的HttpClient（connectionManager）; 
    			... 
            //然后从执行方法的某个线程内部
            GetMethod get = new GetMethod（“http://httpcomponents.apache.org/”）; 
            尝试{ 
                client.executeMethod（get）; 
                //打印对stdout 
                System.out.println的响应（get.getResponseBodyAsStream（））; 
            } finally { 
                //确保连接被释放回连接
                // manager 
                get.releaseConnection（）; 
            }

# 参数 #

MultiThreadedHttpConnectionManager支持以下选项：

<table style="margin-left:-2px;"> 
 <tbody> 
  <tr> 
   <td style="vertical-align:top;">connectionStaleCheckingEnabled</td> 
   <td style="vertical-align:top;">该connectionStaleCheckingEnabled标志上的所有创建的连接设置。除特殊情况外，该值应保留为真。有关&nbsp;更多详细信息，请参阅&nbsp;<a href="http://hc.apache.org/httpclient-3.x/apidocs/org/apache/commons/httpclient/HttpConnection.html#setStaleCheckingEnabled%28boolean%29" rel="nofollow">HttpConnection</a>文档。</td> 
  </tr> 
  <tr> 
   <td style="vertical-align:top;">maxConnectionsPerHost</td> 
   <td style="vertical-align:top;">将为任何特定HostConfiguration创建的最大连接数。默认为2。</td> 
  </tr> 
  <tr> 
   <td style="vertical-align:top;">maxTotalConnections</td> 
   <td style="vertical-align:top;"> <p>最大活动连接数。默认为20。</p> </td> 
  </tr> 
 </tbody> 
</table>

# 配置重要参数 #

有两个重要参数：MaxTotalConnections，MaxConnectionsPerHost（默认为2）

这两个参数同时影响连接数大小，如果只配置一个参数的话，会导致总连接数为2->MaxConnectionsPerHost

# 导致问题 #

n多连接上来而无法从ConnectManager中获取连接，导致很多线程阻塞，占用端口

# 源码 #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zODMzNjY1OA_size_16_color_FFFFFF_t_70][]

转自[https://mp.weixin.qq.com/s?\_\_biz=MzIwMDY0Nzk2Mw==&mid=2650320462&idx=1&sn=393196c09dc30e7c295266c5dfbfdcd3&chksm=8ef5fa3ab982732c5adc921f9bb07de0713eb0531d5132c62de2fc4abdcd105e82446a90b91c&mpshare=1&scene=24&srcid=0720oqwh3wVW7ZYd27wo5vgi\#rd][https_mp.weixin.qq.com_s_biz_MzIwMDY0Nzk2Mw_mid_2650320462_idx_1_sn_393196c09dc30e7c295266c5dfbfdcd3_chksm_8ef5fa3ab982732c5adc921f9bb07de0713eb0531d5132c62de2fc4abdcd105e82446a90b91c_mpshare_1_scene_24_srcid_0720oqwh3wVW7ZYd27wo5vgi_rd]

# 正确的事例 #

final String url= "http://www.taobao.com" ;  
                 final HttpClient client = new HttpClient();  
                 final MultiThreadedHttpConnectionManager connectionManager = new 
                 MultiThreadedHttpConnectionManager();  
                 connectionManager.setMaxTotalConnections (1);//总的连接数  
                 connectionManager.setMaxConnectionsPerHost (2);//每个host的最大连接数  
                 client.setHttpConnectionManager( connectionManager );

# httpclient官网 #

[threading目录下][threading]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zODMzNjY1OA_size_16_color_FFFFFF_t_70]: /images/20211201/615d9f408d6c49779042c742ff3d75c9.png
[https_mp.weixin.qq.com_s_biz_MzIwMDY0Nzk2Mw_mid_2650320462_idx_1_sn_393196c09dc30e7c295266c5dfbfdcd3_chksm_8ef5fa3ab982732c5adc921f9bb07de0713eb0531d5132c62de2fc4abdcd105e82446a90b91c_mpshare_1_scene_24_srcid_0720oqwh3wVW7ZYd27wo5vgi_rd]: https://mp.weixin.qq.com/s?__biz=MzIwMDY0Nzk2Mw==&mid=2650320462&idx=1&sn=393196c09dc30e7c295266c5dfbfdcd3&chksm=8ef5fa3ab982732c5adc921f9bb07de0713eb0531d5132c62de2fc4abdcd105e82446a90b91c&mpshare=1&scene=24&srcid=0720oqwh3wVW7ZYd27wo5vgi#rd
[threading]: http://hc.apache.org/httpclient-3.x/threading.html