httpClient入门到精通-------连接池

package cn.itcast.httpclient;import org.apache.http.client.methods.CloseableHttpResponse;import org.apache.http.client.methods.HttpGet;import org.apache.http.conn.HttpClientConnectionManager;import org.apache.http.impl.client.CloseableHttpClient;import org.apache.http.impl.client.HttpClients;import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;import org.apache.http.util.EntityUtils;public class HttpConnectManager {    public static void main(String[] args) throws Exception {        PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager();        // 设置最大连接数        cm.setMaxTotal(200);        // 设置每个主机地址的并发数        cm.setDefaultMaxPerRoute(20);        doGet(cm);        doGet(cm);    }    public static void doGet(HttpClientConnectionManager cm) throws Exception {        CloseableHttpClient httpClient = HttpClients.custom().setConnectionManager(cm).build();        // 创建http GET请求        HttpGet httpGet = new HttpGet("http://www.baidu.com/");        CloseableHttpResponse response = null;        try {            // 执行请求            response = httpClient.execute(httpGet);            // 判断返回状态是否为200            if (response.getStatusLine().getStatusCode() == 200) {                String content = EntityUtils.toString(response.getEntity(), "UTF-8");                System.out.println("内容长度：" + content.length());            }        } finally {            if (response != null) {                response.close();            }            // 此处不能关闭httpClient，如果关闭httpClient，连接池也会销毁            // httpClient.close();        }    }}