HttpClient 4.0.1 - 如何释放连接？

Question

HttpClient 4.0.1 - 如何释放连接？

74

我有一个循环遍历一堆URL，对于每个URL，我正在执行以下操作：

private String doQuery(String url) {

  HttpGet httpGet = new HttpGet(url);
  setDefaultHeaders(httpGet); // static method
  HttpResponse response = httpClient.execute(httpGet);   // httpClient instantiated in constructor

  int rc = response.getStatusLine().getStatusCode();

  if (rc != 200) {
    // some stuff...
    return;
  }

  HttpEntity entity = response.getEntity();

  if (entity == null) {
    // some stuff...
    return;
  }

  // process the entity, get input stream etc

}

第一次查询没问题，第二次会抛出以下异常：

Exception in thread "main" java.lang.IllegalStateException: Invalid use of SingleClientConnManager: connection still allocated. Make sure to release the connection before allocating another one. at org.apache.http.impl.conn.SingleClientConnManager.getConnection(SingleClientConnManager.java:199) at org.apache.http.impl.conn.SingleClientConnManager$1.getConnection(SingleClientConnManager.java:173)......

这只是一个简单的单线程应用程序。如何释放连接？

- Richard H

相关：使用HttpRequest.execute()时出现异常：Invalid use of SingleClientConnManager: connection still allocated - blahdiblah

12个回答

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- Lincoln · Answer 1

强烈建议使用处理程序来处理响应。

client.execute(yourRequest,defaultHanler);

使用 consume(HTTPENTITY) 方法会自动释放连接。

以下是处理程序示例：

private ResponseHandler<String> defaultHandler = new ResponseHandler<String>() {
    @Override
    public String handleResponse(HttpResponse response)
        throws IOException {
        int status = response.getStatusLine().getStatusCode();

        if (status >= 200 && status < 300) {
            HttpEntity entity = response.getEntity();
            return entity != null ? EntityUtils.toString(entity) : null;
        } else {
            throw new ClientProtocolException("Unexpected response status: " + status);
        }
    }
};

- kerl · Answer 2

我遇到了同样的问题，并通过在方法结束处关闭响应来解决它。

try {
    // make the request and get the entity 
} catch(final Exception e) {
    // handle the exception
} finally {
    if(response != null) {
        response.close();
    }
}