HttpClient工具正确使用方式

虽然现在基于netty和thift的微服务非常的流行，但是公司内部的蛮多系统仍然对外提供http接口。在调用http接口工具类中，apache httpclient工具用的比较多。下面列举一些正确使用httpclient的一些要点。

设置socketTimeout

可以在RequestConfig 中设置socketTimeout，表示数据传输处理时间，如下：

 RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(4000).build()
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设置connectionRequestTimeout

可以在RequestConfig 中设置socketTimeout，表示从连接池中后去连接的timeout时间，如下：

RequestConfig requestConfig = RequestConfig.custom().setConnectionRequestTimeout(1000)
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设置connectTimeout

可以在RequestConfig 中设置connectTimeout，表示建立连接的timeout时间，如下：

RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(3000).build();
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设置MaxTotal

MaxTotal表示连接池最大并发连接数，代码如下：

PoolingHttpClientConnectionManager pccm = new PoolingHttpClientConnectionManager();    pccm.setMaxTotal(300); 
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设置DefaultMaxPerRout

DefaultMaxPerRout表示单路由的最大并发连接数，假设你的业务系统需要调用A和B这两个外部系统的http接口，那么如果DefaultMaxPerRout=100，那么调用A系统的http接口时，最大并发数就是100。代码如下：

PoolingHttpClientConnectionManager pccm = new PoolingHttpClientConnectionManager();    pccm.setDefaultMaxPerRoute(100); // 单路由最大并发数
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尽量不要设置超时重试次数

如果要设置的话，可以如下设置：

// 设置默认时间     RequestConfig params = RequestConfig.custom().setConnectTimeout(3000).setConnectionRequestTimeout(1000).setSocketTimeout(4000)        .setExpectContinueEnabled(true).build();    PoolingHttpClientConnectionManager pccm = new PoolingHttpClientConnectionManager();    pccm.setMaxTotal(300); // 连接池最大并发连接数    pccm.setDefaultMaxPerRoute(50); // 单路由最大并发数HttpRequestRetryHandler retryHandler = new HttpRequestRetryHandler() {      public boolean retryRequest(IOException exception , int executionCount , HttpContext context) {        if (executionCount > 3) {          return false;        }        if (exception instanceof NoHttpResponseException) {          LOGGER.info(              "[NoHttpResponseException has retry request:" + context.toString() + "][executionCount:" + executionCount + "]");          return true;        }        else if (exception instanceof SocketException) {          LOGGER.info("[SocketException has retry request:" + context.toString() + "][executionCount:" + executionCount + "]");          return true;        }        return false;      }    };    httpclient = HttpClients.custom().setConnectionManager(pccm).setDefaultRequestConfig(params).setRetryHandler(retryHandler)        .build();
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完整代码

package test;import java.io.IOException;import java.io.UnsupportedEncodingException;import java.net.SocketException;import java.util.ArrayList;import java.util.List;import java.util.Map;import java.util.Map.Entry;import org.apache.http.HttpEntity;import org.apache.http.HttpStatus;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.HttpPost;import org.apache.http.client.methods.HttpUriRequest;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;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import com.alibaba.fastjson.JSON;public class HttpClientUtils {  private final static Logger LOGGER = LoggerFactory.getLogger(HttpClientUtils.class);  private final static String UTF8 = "UTF-8";  public static CloseableHttpClient httpclient = null;  static {    // 初始化线程池    RequestConfig params = RequestConfig.custom().setConnectTimeout(3000).setConnectionRequestTimeout(1000).setSocketTimeout(4000)        .setExpectContinueEnabled(true).build();    PoolingHttpClientConnectionManager pccm = new PoolingHttpClientConnectionManager();    pccm.setMaxTotal(300); // 连接池最大并发连接数    pccm.setDefaultMaxPerRoute(50); // 单路由最大并发数    HttpRequestRetryHandler retryHandler = new HttpRequestRetryHandler() {      public boolean retryRequest(IOException exception , int executionCount , HttpContext context) {        // 重试1次,从1开始        if (executionCount > 1) {          return false;        }        if (exception instanceof NoHttpResponseException) {          LOGGER.info(              "[NoHttpResponseException has retry request:" + context.toString() + "][executionCount:" + executionCount + "]");          return true;        }        else if (exception instanceof SocketException) {          LOGGER.info("[SocketException has retry request:" + context.toString() + "][executionCount:" + executionCount + "]");          return true;        }        return false;      }    };    httpclient = HttpClients.custom().setConnectionManager(pccm).setDefaultRequestConfig(params).setRetryHandler(retryHandler)        .build();  }  public static String post(String urlToRequest , Map<String, Object> parameters , Integer connectionRequestTimeout ,      Integer connectTimeout , Integer socketTimeout) {    Long startTs = System.currentTimeMillis();    List<NameValuePair> nvps = new ArrayList<NameValuePair>();    if (parameters != null && !parameters.isEmpty()) {      for (Entry<String, Object> entry : parameters.entrySet()) {        nvps.add(new BasicNameValuePair(entry.getKey(), String.valueOf(entry.getValue())));      }    }    try {      LOGGER.info("post-req:url:{},param:{}", urlToRequest, JSON.toJSONString(parameters));      HttpPost post = new HttpPost(urlToRequest);      if (connectionRequestTimeout != null && connectTimeout != null && socketTimeout != null) {        RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(connectTimeout)            .setConnectionRequestTimeout(connectionRequestTimeout).setSocketTimeout(socketTimeout).build();        post.setConfig(requestConfig);      }      post.setEntity(new UrlEncodedFormEntity(nvps, UTF8));      String result = invoke(post);      Long endTs = System.currentTimeMillis();      Long currentMethodCallTime = endTs - startTs;      if (currentMethodCallTime > 5000) {        LOGGER.warn("url:{},call time {} ms", urlToRequest, currentMethodCallTime);        LOGGER.info("所有存活线程="+Thread.getAllStackTraces().size());      }      LOGGER.info("post-rps:{}", result);      return result;    }    catch (UnsupportedEncodingException e) {      LOGGER.error("[HttpClientUtils][post][Unsupported Encoding Exception]", e);    }    return null;  }  private static String invoke(HttpUriRequest request) {    CloseableHttpResponse response = null;    try {      response = httpclient.execute(request);      if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {        HttpEntity entity = response.getEntity();        return EntityUtils.toString(entity, UTF8);      }    }    catch (IOException e) {      LOGGER.error(          "[HttpClientUtils][invoke][method:" + request.getMethod() + " URI:" + request.getURI() + "] is request exception", e);    }    finally {      if (response != null) {        try {          response.close();        }        catch (IOException e) {          LOGGER.error(              "[HttpClientUtils][invoke][method:" + request.getMethod() + " URI:" + request.getURI() + "] is closed exception",              e);        }      }    }    return null;  }}