Http请求连接池

装载自http://blog.csdn.net/catoop/article/details/50352334

两个主机建立连接的过程是很复杂的一个过程，涉及到多个数据包的交换，并且也很耗时间。Http连接需要的三次握手开销很大，这一开销对于比较小的http消息来说更大。但是如果我们直接使用已经建立好的http连接，这样花费就比较小，吞吐率更大。
传统的HttpURLConnection并不支持连接池，如果要实现连接池的机制，还需要自己来管理连接对象。对于网络请求这种底层相对复杂的操作，个人以为如果有可用的其他方案，也没有必要自己去管理连接对象。

除了HttpURLConnection，大家肯定还知道HttpClient。一般情况下，普通使用HttpClient已经能满足我们的需求，不过有时候，在我们需要高并发大量的请求网络的时候，还是用“连接池”这样的概念能提升吞吐量。

我们来看下怎么使用 org.apache.httpcomponents.httpclient（版本4.4）提供的连接池来实现我们的高并发网络请求。

使用到的jar包：
org\apache\httpcomponents\httpclient\4.4-beta1\httpclient-4.4-beta1.jar
org\apache\httpcomponents\httpclient-cache\4.4-beta1\httpclient-cache-4.4-beta1.jar
org\apache\httpcomponents\httpcore\4.4-beta1\httpcore-4.4-beta1.jar

下面代码实例中主要使用到 PoolingHttpClientConnectionManager

package com.hvgroup.zhuhai10086.jms.utils;import java.io.IOException;import java.io.InterruptedIOException;import java.io.UnsupportedEncodingException;import java.net.UnknownHostException;import java.util.ArrayList;import java.util.List;import java.util.Map;import java.util.Set;import java.util.concurrent.CountDownLatch;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import javax.net.ssl.SSLException;import javax.net.ssl.SSLHandshakeException;import org.apache.http.HttpEntity;import org.apache.http.HttpEntityEnclosingRequest;import org.apache.http.HttpHost;import org.apache.http.HttpRequest;import org.apache.http.NameValuePair;import org.apache.http.NoHttpResponseException;import org.apache.http.client.HttpRequestRetryHandler;import org.apache.http.client.config.RequestConfig;import org.apache.http.client.entity.UrlEncodedFormEntity;import org.apache.http.client.methods.CloseableHttpResponse;import org.apache.http.client.methods.HttpGet;import org.apache.http.client.methods.HttpPost;import org.apache.http.client.methods.HttpRequestBase;import org.apache.http.client.protocol.HttpClientContext;import org.apache.http.config.Registry;import org.apache.http.config.RegistryBuilder;import org.apache.http.conn.ConnectTimeoutException;import org.apache.http.conn.routing.HttpRoute;import org.apache.http.conn.socket.ConnectionSocketFactory;import org.apache.http.conn.socket.LayeredConnectionSocketFactory;import org.apache.http.conn.socket.PlainConnectionSocketFactory;import org.apache.http.conn.ssl.SSLConnectionSocketFactory;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.message.BasicNameValuePair;import org.apache.http.protocol.HttpContext;import org.apache.http.util.EntityUtils;/** * HttpClient工具类 *  * @return * @author SHANHY * @create 2015年12月18日 */public class HttpClientUtil {    static final int timeOut = 10 * 1000;    private static CloseableHttpClient httpClient = null;    private final static Object syncLock = new Object();    private static void config(HttpRequestBase httpRequestBase) {        // 设置Header等        // httpRequestBase.setHeader("User-Agent", "Mozilla/5.0");        // httpRequestBase        // .setHeader("Accept",        // "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");        // httpRequestBase.setHeader("Accept-Language",        // "zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3");// "en-US,en;q=0.5");        // httpRequestBase.setHeader("Accept-Charset",        // "ISO-8859-1,utf-8,gbk,gb2312;q=0.7,*;q=0.7");        // 配置请求的超时设置        RequestConfig requestConfig = RequestConfig.custom()                .setConnectionRequestTimeout(timeOut)                .setConnectTimeout(timeOut).setSocketTimeout(timeOut).build();        httpRequestBase.setConfig(requestConfig);    }    /**     * 获取HttpClient对象     *      * @return     * @author SHANHY     * @create 2015年12月18日     */    public static CloseableHttpClient getHttpClient(String url) {        String hostname = url.split("/")[2];        int port = 80;        if (hostname.contains(":")) {            String[] arr = hostname.split(":");            hostname = arr[0];            port = Integer.parseInt(arr[1]);        }        if (httpClient == null) {            synchronized (syncLock) {                if (httpClient == null) {                    httpClient = createHttpClient(200, 40, 100, hostname, port);                }            }        }        return httpClient;    }    /**     * 创建HttpClient对象     *      * @return     * @author SHANHY     * @create 2015年12月18日     */    public static CloseableHttpClient createHttpClient(int maxTotal,            int maxPerRoute, int maxRoute, String hostname, int port) {        ConnectionSocketFactory plainsf = PlainConnectionSocketFactory                .getSocketFactory();        LayeredConnectionSocketFactory sslsf = SSLConnectionSocketFactory                .getSocketFactory();        Registry<ConnectionSocketFactory> registry = RegistryBuilder                .<ConnectionSocketFactory> create().register("http", plainsf)                .register("https", sslsf).build();        PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager(                registry);        // 将最大连接数增加        cm.setMaxTotal(maxTotal);        // 将每个路由基础的连接增加        cm.setDefaultMaxPerRoute(maxPerRoute);        HttpHost httpHost = new HttpHost(hostname, port);        // 将目标主机的最大连接数增加        cm.setMaxPerRoute(new HttpRoute(httpHost), maxRoute);        // 请求重试处理        HttpRequestRetryHandler httpRequestRetryHandler = new HttpRequestRetryHandler() {            public boolean retryRequest(IOException exception,                    int executionCount, HttpContext context) {                if (executionCount >= 5) {// 如果已经重试了5次，就放弃                    return false;                }                if (exception instanceof NoHttpResponseException) {// 如果服务器丢掉了连接，那么就重试                    return true;                }                if (exception instanceof SSLHandshakeException) {// 不要重试SSL握手异常                    return false;                }                if (exception instanceof InterruptedIOException) {// 超时                    return false;                }                if (exception instanceof UnknownHostException) {// 目标服务器不可达                    return false;                }                if (exception instanceof ConnectTimeoutException) {// 连接被拒绝                    return false;                }                if (exception instanceof SSLException) {// SSL握手异常                    return false;                }                HttpClientContext clientContext = HttpClientContext                        .adapt(context);                HttpRequest request = clientContext.getRequest();                // 如果请求是幂等的，就再次尝试                if (!(request instanceof HttpEntityEnclosingRequest)) {                    return true;                }                return false;            }        };        CloseableHttpClient httpClient = HttpClients.custom()                .setConnectionManager(cm)                .setRetryHandler(httpRequestRetryHandler).build();        return httpClient;    }    private static void setPostParams(HttpPost httpost,            Map<String, Object> params) {        List<NameValuePair> nvps = new ArrayList<NameValuePair>();        Set<String> keySet = params.keySet();        for (String key : keySet) {            nvps.add(new BasicNameValuePair(key, params.get(key).toString()));        }        try {            httpost.setEntity(new UrlEncodedFormEntity(nvps, "UTF-8"));        } catch (UnsupportedEncodingException e) {            e.printStackTrace();        }    }    /**     * GET请求URL获取内容     *      * @param url     * @return     * @author SHANHY     * @throws IOException      * @create 2015年12月18日     */    public static String post(String url, Map<String, Object> params) throws IOException {        HttpPost httppost = new HttpPost(url);        config(httppost);        setPostParams(httppost, params);        CloseableHttpResponse response = null;        try {            response = getHttpClient(url).execute(httppost,                    HttpClientContext.create());            HttpEntity entity = response.getEntity();            String result = EntityUtils.toString(entity, "utf-8");            EntityUtils.consume(entity);            return result;        } catch (Exception e) {//          e.printStackTrace();            throw e;        } finally {            try {                if (response != null)                    response.close();            } catch (IOException e) {                e.printStackTrace();            }        }    }    /**     * GET请求URL获取内容     *      * @param url     * @return     * @author SHANHY     * @create 2015年12月18日     */    public static String get(String url) {        HttpGet httpget = new HttpGet(url);        config(httpget);        CloseableHttpResponse response = null;        try {            response = getHttpClient(url).execute(httpget,                    HttpClientContext.create());            HttpEntity entity = response.getEntity();            String result = EntityUtils.toString(entity, "utf-8");            EntityUtils.consume(entity);            return result;        } catch (IOException e) {            e.printStackTrace();        } finally {            try {                if (response != null)                    response.close();            } catch (IOException e) {                e.printStackTrace();            }        }        return null;    }    public static void main(String[] args) {        // URL列表数组        String[] urisToGet = {                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497",                "http://blog.csdn.net/catoop/article/details/38849497" };        long start = System.currentTimeMillis();        try {            int pagecount = urisToGet.length;            ExecutorService executors = Executors.newFixedThreadPool(pagecount);            CountDownLatch countDownLatch = new CountDownLatch(pagecount);            for (int i = 0; i < pagecount; i++) {                HttpGet httpget = new HttpGet(urisToGet[i]);                config(httpget);                // 启动线程抓取                executors                        .execute(new GetRunnable(urisToGet[i], countDownLatch));            }            countDownLatch.await();            executors.shutdown();        } catch (InterruptedException e) {            e.printStackTrace();        } finally {            System.out.println("线程" + Thread.currentThread().getName() + ","                    + System.currentTimeMillis() + ", 所有线程已完成，开始进入下一步！");        }        long end = System.currentTimeMillis();        System.out.println("consume -> " + (end - start));    }    static class GetRunnable implements Runnable {        private CountDownLatch countDownLatch;        private String url;        public GetRunnable(String url, CountDownLatch countDownLatch) {            this.url = url;            this.countDownLatch = countDownLatch;        }        @Override        public void run() {            try {                System.out.println(HttpClientUtil.get(url));            } finally {                countDownLatch.countDown();            }        }    }}
>
Post使用方法
// 其中 params 为 Map<String, Object> paramsString ret = HttpClientUtil.post(url, params);            jsonRet = new JSONObject(ret);
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一开始我是使用传统的 HttpURLConnection 来做网络请求的，查了很多资料，有不少说 HttpURLConnection 效率高的。可是经过我修改实现方法后，HttpClient 连接池版本的网络请求相对比较稳定。这也说明，我们并不请尽信他人解说，凡事还是要寻找适合自己的方法，真正的解决自己的问题，才是王道。
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在使用 HttpURLConnection 的时候，大并发对外做网络请求的时候，前期请求耗时还好，后面耗时越来越高。下面是我之前的实现代码：
    @Deprecated    protected JSONObject callRestfulOld(String url, Map<String, Object> params)     {        String temp;        String ret="";        JSONObject jsonRet=null;        String sign = generateSign("POST", url, params);// 对参数进行加密签名        if(sign.isEmpty()) return new JSONObject("{\"ret_code\":-1,\"err_msg\":\"generateSign error\"}");        params.put("sign", sign);        try{            URL u = new URL(url);            HttpURLConnection conn = (HttpURLConnection)u.openConnection();            conn.setRequestMethod("POST");            conn.setConnectTimeout(10000);            conn.setDoOutput(true);            conn.setDoInput(true);            conn.setUseCaches(false);            StringBuffer param = new StringBuffer();            for (String key: params.keySet())            {                param.append(key).append("=").append(URLEncoder.encode(params.get(key).toString(), "UTF-8")).append("&");            }            conn.getOutputStream().write(param.toString().getBytes("UTF-8"));
        //System<span class="hljs-preprocessor">.out</span><span class="hljs-preprocessor">.println</span>(param)<span class="hljs-comment">;</span>        conn<span class="hljs-preprocessor">.getOutputStream</span>()<span class="hljs-preprocessor">.flush</span>()<span class="hljs-comment">;</span>        conn<span class="hljs-preprocessor">.getOutputStream</span>()<span class="hljs-preprocessor">.close</span>()<span class="hljs-comment">;</span>        InputStreamReader isr = new InputStreamReader(conn<span class="hljs-preprocessor">.getInputStream</span>())<span class="hljs-comment">;  </span>        BufferedReader br = new BufferedReader(isr)<span class="hljs-comment">;  </span>        while((temp = br<span class="hljs-preprocessor">.readLine</span>()) != null){              <span class="hljs-keyword">ret</span> += temp<span class="hljs-comment">;  </span>        }             br<span class="hljs-preprocessor">.close</span>()<span class="hljs-comment">;  </span>        isr<span class="hljs-preprocessor">.close</span>()<span class="hljs-comment">;</span>        conn<span class="hljs-preprocessor">.disconnect</span>()<span class="hljs-comment">;</span>        //System<span class="hljs-preprocessor">.out</span><span class="hljs-preprocessor">.println</span>(<span class="hljs-keyword">ret</span>)<span class="hljs-comment">;</span>        jsonRet = new JSONObject(<span class="hljs-keyword">ret</span>)<span class="hljs-comment">;</span>    } catch(java<span class="hljs-preprocessor">.net</span><span class="hljs-preprocessor">.SocketTimeoutException</span> e) {        //e<span class="hljs-preprocessor">.printStackTrace</span>()<span class="hljs-comment">;</span>        jsonRet = new JSONObject(<span class="hljs-string">"{\"ret_code\":-1,\"err_msg\":\"call restful timeout\"}"</span>)<span class="hljs-comment">;</span>    } catch(Exception e) {        //e<span class="hljs-preprocessor">.printStackTrace</span>()<span class="hljs-comment">;</span>        jsonRet = new JSONObject(<span class="hljs-string">"{\"ret_code\":-1,\"err_msg\":\"call restful error\"}"</span>)<span class="hljs-comment">;</span>    }    return jsonRet<span class="hljs-comment">;</span>}</code>