导入以下依赖:

<!--httpclient-->
<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.1</version>
</dependency>


<!-- 需加上classifier: jdk15 -->
<dependency>
    <groupId>net.sf.json-lib</groupId>
    <artifactId>json-lib</artifactId>
    <version>2.4</version>
    <classifier>jdk15</classifier>
</dependency>

工具类: HttpClientUtils.java

package com.idea.fire.firecontrol.utils;

import net.sf.json.JSONObject;
import org.apache.http.*;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;

//模拟浏览器发送http请求完成固定地址的请求
public class HttpClientUtils {

	/**
	 * 发送post请求
	 * @param url
	 * @param json
	 * @return
	 */
	public static JSONObject DO_POST(String url, JSONObject json){
		DefaultHttpClient client = new DefaultHttpClient();
		HttpPost post = new HttpPost(url);
		JSONObject response = null;
		try {
			StringEntity s = new StringEntity(json.toString());
			s.setContentEncoding("UTF-8");
			s.setContentType("application/json");//发送json数据需要设置contentType
			post.setEntity(s);
			HttpResponse res = client.execute(post);
			if(res.getStatusLine().getStatusCode() == HttpStatus.SC_OK){
				HttpEntity entity = res.getEntity();
				String result = EntityUtils.toString(res.getEntity());// 返回json格式：
				response = JSONObject.fromObject(result);
			}
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
		return response;
	}
}

 准备被请求接口:

@RestController
@RequestMapping("user")
public class UserController {

    @PostMapping("login")
    public R login(@RequestBody User user)
    {
        return R.ok().data("user", user);
    }
}

测试:

public static void main(String[] args) throws Exception {
    JSONObject params = new JSONObject();
    params.put("username", "admin");
    params.put("password", "admin");
    System.out.println(HttpClientUtils.DO_POST("ip/user/login", params));
}

控制台输出:

java发送post formdata java发送post请求带参数_java