在开始之前，我们需要先引入 maven 依赖。如下：
<dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.5.2</version> </dependency> <dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpmime</artifactId> <version>4.5.2</version> </dependency>
注意：提交表单的 MultipartEntityBuilder 类需要引入 httpmime 库。
实例1：提交一个JSON数据到后端，即我们常说的 Restful 接口。代码如下：
package com.huangx.httpcomponents;
import com.alibaba.fastjson.JSONObject;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
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.DefaultHttpClient;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map;
/**
* 使用 http components 发起 POST 请求
* @author huangxin 2019/12/2
*/
public class PostDemo {
public static void main(String[] args) throws Exception {
// (1) 创建HttpGet实例
HttpPost post = new HttpPost("https://127.0.0.1:8080/env/postEnvObj");
// (2) 设置请求体
Map<String,Object> data = new HashMap<>();
data.put("name", "admin");
data.put("email", "admin@163.com");
StringEntity myEntity = new StringEntity(JSONObject.toJSONString(data), ContentType.APPLICATION_JSON);
post.setEntity(myEntity);
// (3) 使用HttpClient发送get请求，获得返回结果HttpResponse
HttpClient http = new DefaultHttpClient();
HttpResponse response = http.execute(post);
// (4) 读取返回结果
int statusCode = response.getStatusLine().getStatusCode();
System.out.println("statusCode=" + statusCode);
if (statusCode == 200) {
HttpEntity entity = response.getEntity();
InputStream in = entity.getContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
String line;
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
reader.close();
}
}
}服务端代码如下：
/**
* 使用 JSON 格式提交数据到服务端
* @param userEntity 用户数据
* @return
*/
@RequestMapping(value = "/postEnvObj", method = RequestMethod.POST)
@ResponseBody
public String postEnvObj(@RequestBody UserEntity userEntity) {
LOG.info("#### /postEnvObj userEntity={}", JSONObject.toJSONString(userEntity));
Map<String,Object> retData = new HashMap<>();
retData.put("timestamp", new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS").format(new Date()));
retData.put("content", userEntity);
return JSONObject.toJSONString(retData, true);
}注意：服务端我采用Spring Boot进行实现。
实例2：使用 POST 方式提交一个表单到后端服务器。代码如下：
package com.huangx.httpcomponents;
import org.apache.http.Consts;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.mime.MultipartEntityBuilder;
import org.apache.http.entity.mime.content.StringBody;
import org.apache.http.impl.client.DefaultHttpClient;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
/**
* 使用 http components 发起 POST 请求，提交表单数据
* @author huangxin 2019/12/2
*/
public class PostDemo2 {
public static void main(String[] args) throws Exception {
// (1) 创建HttpGet实例
HttpPost post = new HttpPost("https://127.0.0.1:8080/env/postEnv");
// (2) 设置请求体
// 提交表单数据
MultipartEntityBuilder builder = MultipartEntityBuilder.create();
builder.addPart("name", new StringBody("admin", ContentType.create("text/plain", Consts.UTF_8)));
builder.addPart("email", new StringBody("admin@163.com", ContentType.create("text/plain", Consts.UTF_8)));
HttpEntity reqEntity = builder.build();
post.setEntity(reqEntity);
// (3) 使用HttpClient发送get请求，获得返回结果HttpResponse
HttpClient http = new DefaultHttpClient();
HttpResponse response = http.execute(post);
// (4) 读取返回结果
int statusCode = response.getStatusLine().getStatusCode();
System.out.println("statusCode=" + statusCode);
if (statusCode == 200) {
HttpEntity entity = response.getEntity();
InputStream in = entity.getContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
String line;
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
reader.close();
}
}
}服务端代码如下：
/**
* 提交表单数据到服务端，然后将数据返回
* @param name 名称
* @param email 邮箱
* @return
*/
@RequestMapping(value = "/postEnv", method = RequestMethod.POST)
@ResponseBody
public String postEnv(String name, String email) {
LOG.info("#### /postEnv name={}, email={}", name, email);
Map<String,Object> retData = new HashMap<>();
retData.put("timestamp", new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS").format(new Date()));
Map<String,Object> content = new HashMap<>();
content.put("name", name);
content.put("email", email);
retData.put("content", content);
return JSONObject.toJSONString(retData, true);
}
