大家好，又见面了，我是你们的朋友全栈君。

httpComponents HttpClient4.x

获取httpClient

CloseableHttpClient httpClient = HttpClients.custom()
    .setMaxConnTotal(config.maxConnTotal)
    .setMaxConnPerRoute(config.maxConnPerRoute)
    .setDefaultRequestConfig(requestConfig);

或者    

PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager();
    connectionManager.setMaxTotal(maxTotal);
    connectionManager.setDefaultMaxPerRoute(defaultMaxPerRoute);
    //可用空闲连接过期时间,重用空闲连接时会先检查是否空闲时间超过这个时间，如果超过，释放socket重新建
    connectionManager.setValidateAfterInactivity(validateAfterInactivity);

CloseableHttpClient httpClient = HttpClients.custom()
    .setConnectionManager(connectionManager)
    .setRetryHandler(new DefaultHttpRequestRetryHandler())
    .build();

获取httpRequestBase

RequestConfig requestConfig = RequestConfig.custom()
    .setConnectionRequestTimeout(config.connReqTimeout)
    .setConnectTimeout(config.connTimeout)
    .setSocketTimeout(config.socketTimeout)
    .build();
    
HttpRequestBase httpRequestBase = new HttpGet/HttpPost/HttpDelete(url);
httpRequestBase.setConfig(requestConfig);
httpRequestBase.setxxx();

调用

CloseableHttpResponse response = httpClient.execute(httpRequestBase);

关闭

response.close();

HttpClient HttpClient3.x

获取HttpClient

MultiThreadedHttpConnectionManager httpConnectionManager = new MultiThreadedHttpConnectionManager();
    httpConnectionManager.getParams().setDefaultMaxConnectionsPerHost(maxConnectionsPerHost);
    httpConnectionManager.getParams().setMaxTotalConnections(maxTotalConnections);
    //4.x版本提供connectionManager.setValidateAfterInactivity(validateAfterInactivity);
    httpConnectionManager.getParams().setStaleCheckingEnabled(false/true);
    httpConnectionManager.getParams().setLinger(linger);
    httpConnectionManager.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler());
    httpConnectionManager.getParams().setConnectionTimeout(connectionTimeout);
    httpConnectionManager.getParams().setSoTimeout(soTimeout);

HttpClient httpClient = new HttpClient(httpConnectionManager);

获取method

EntityEnclosingMethod method = new PostMethod(url);
method.setxxx();

调用

client.executeMethod(method);

关闭

method.releaseConnection();