使用Apache HttpClient 4.x发送Json数据

Apache HttpClient是Apache提供的一个开源组件，使用HttpClient可以很方便地进行Http请求的调用。自4.1版本开始，HttpClient的API发生了较大的改变，很多方法的调用方式已经和3.x版本不同。本文使用的是当前最新的4.5.3版本。

首先在pom文件中引入httpcomponents依赖包：

 <dependency>
     <groupId>org.apache.httpcomponents</groupId>
     <artifactId>httpclient</artifactId>
     <version>4.5.3</version>
 </dependency>

本文展示的是POST请求。

 import java.io.IOException;
 
 import org.apache.commons.lang3.ObjectUtils;
 import org.apache.commons.lang3.StringUtils;
 import org.apache.http.Consts;
 import org.apache.http.HttpStatus;
 import org.apache.http.ParseException;
 import org.apache.http.client.config.RequestConfig;
 import org.apache.http.client.methods.CloseableHttpResponse;
 import org.apache.http.client.methods.HttpPost;
 import org.apache.http.entity.ContentType;
 import org.apache.http.entity.StringEntity;
 import org.apache.http.impl.client.CloseableHttpClient;
 import org.apache.http.impl.client.HttpClients;
 import org.apache.http.util.EntityUtils;
 
 /**
  * @author
  *
  * @date 2017年5月18日 上午9:17:30
  *
  * @Description
  */
 public class HttpPostUtils {
     /**
      *
      * @param uri
      *            the request address
      * @param json
      *            the request data that must be a JSON string
      * @param connectTimeout
      *            the timeout in milliseconds until a connection is established
      * @param connectionRequestTimeout
      *            the timeout in milliseconds used when requesting a connection
      *            from the connection manager
      * @param socketTimeout
      *            the socket timeout in milliseconds, which is the timeout for
      *            waiting for data or, put differently, a maximum period
      *            inactivity between two consecutive data packets
      * @return null when method parameter is null, "", " "
      * @throws IOException
      *             if HTTP connection can not opened or closed successfully
      * @throws ParseException
      *             if response data can not be parsed successfully
      */
     public String postJson(String uri, String json, int connectTimeout, int connectionRequestTimeout, int socketTimeout)
             throws IOException, ParseException {
         if (StringUtils.isAnyBlank(uri, json)) {
             return null;
         }
 
         CloseableHttpClient client = HttpClients.createDefault();
         HttpPost post = new HttpPost(uri);
         // Create request data
         StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
         // Set request body
         post.setEntity(entity);
 
         RequestConfig config = RequestConfig.custom().setConnectTimeout(connectTimeout)
                 .setConnectionRequestTimeout(connectionRequestTimeout).setSocketTimeout(socketTimeout).build();
         post.setConfig(config);
         // Response content
         String responseContent = null;
         CloseableHttpResponse response = null;
         try {
             response = client.execute(post);
             if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                 responseContent = EntityUtils.toString(response.getEntity(), Consts.UTF_8.name());
             }
         } finally {
             if (ObjectUtils.anyNotNull(response)) {
                 response.close();
             }
             if (ObjectUtils.anyNotNull(client)) {
                 client.close();
             }
         }
         return responseContent;
     }
 }