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：

1 <dependency>
2     <groupId>org.apache.httpcomponents</groupId>
3     <artifactId>httpclient</artifactId>
4     <version>4.5.3</version>
5 </dependency>

本文展示的是POST请求。

 1 import java.io.IOException;
 2
 3 import org.apache.commons.lang3.ObjectUtils;
 4 import org.apache.commons.lang3.StringUtils;
 5 import org.apache.http.Consts;
 6 import org.apache.http.HttpStatus;
 7 import org.apache.http.ParseException;
 8 import org.apache.http.client.config.RequestConfig;
 9 import org.apache.http.client.methods.CloseableHttpResponse;
10 import org.apache.http.client.methods.HttpPost;
11 import org.apache.http.entity.ContentType;
12 import org.apache.http.entity.StringEntity;
13 import org.apache.http.impl.client.CloseableHttpClient;
14 import org.apache.http.impl.client.HttpClients;
15 import org.apache.http.util.EntityUtils;
16
17 /**
18  * @author
19  *
20  * @date 2017年5月18日 上午9:17:30
21  *
22  * @Description
23  */
24 public class HttpPostUtils {
25     /**
26      *
27      * @param uri
28      *            the request address
29      * @param json
30      *            the request data that must be a JSON string
31      * @param connectTimeout
32      *            the timeout in milliseconds until a connection is established
33      * @param connectionRequestTimeout
34      *            the timeout in milliseconds used when requesting a connection
35      *            from the connection manager
36      * @param socketTimeout
37      *            the socket timeout in milliseconds, which is the timeout for
38      *            waiting for data or, put differently, a maximum period
39      *            inactivity between two consecutive data packets
40      * @return null when method parameter is null, "", " "
41      * @throws IOException
42      *             if HTTP connection can not opened or closed successfully
43      * @throws ParseException
44      *             if response data can not be parsed successfully
45      */
46     public String postJson(String uri, String json, int connectTimeout, int connectionRequestTimeout, int socketTimeout)
47             throws IOException, ParseException {
48         if (StringUtils.isAnyBlank(uri, json)) {
49             return null;
50         }
51
52         CloseableHttpClient client = HttpClients.createDefault();
53         HttpPost post = new HttpPost(uri);
54         // Create request data
55         StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
56         // Set request body
57         post.setEntity(entity);
58
59         RequestConfig config = RequestConfig.custom().setConnectTimeout(connectTimeout)
60                 .setConnectionRequestTimeout(connectionRequestTimeout).setSocketTimeout(socketTimeout).build();
61         post.setConfig(config);
62         // Response content
63         String responseContent = null;
64         CloseableHttpResponse response = null;
65         try {
66             response = client.execute(post);
67             if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
68                 responseContent = EntityUtils.toString(response.getEntity(), Consts.UTF_8.name());
69             }
70         } finally {
71             if (ObjectUtils.anyNotNull(response)) {
72                 response.close();
73             }
74             if (ObjectUtils.anyNotNull(client)) {
75                 client.close();
76             }
77         }
78         return responseContent;
79     }
80 }