1.创建个实体类

实体类User代码：

package com.neuedu.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.util.Date;

/**
 * Keafmd
 *
 * @ClassName: User
 * @Description: user实体类
 * @author: 牛哄哄的柯南
 * @date: 2020-12-17 14:08
 */

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {

    private Integer id;
    private String name;
    private String address;
    private Date date;

}

我没有自己写构造函数和Setter()，Getter()以及toString()方法，而是使用了lombok自动生成的。

2.使用类库 fastjson

添加依赖：

<dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>fastjson</artifactId>
      <version>1.2.73</version>
</dependency>

3.测试一下

JsonTest 代码：

package com.neuedu.entity;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.serializer.SerializerFeature;
import org.junit.Test;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**
 * Keafmd
 *
 * @ClassName: Test
 * @Description: user测试类
 * @author: 牛哄哄的柯南
 * @date: 2020-12-17 14:10
 */

public class JsonTest {

    @Test
    public void test(){
        List userList = new ArrayList();
        userList.add(new User(1,"牛哄哄的柯南1","某某省某某市1",new Date()));
        userList.add(new User(2,"牛哄哄的柯南2","某某省某某市2",new Date()));
        userList.add(new User(3,"牛哄哄的柯南3","某某省某某市3",new Date()));
        userList.add(new User(4,"牛哄哄的柯南4","某某省某某市4",new Date()));
        userList.add(new User(5,"牛哄哄的柯南5","某某省某某市5",new Date()));
        userList.add(new User(6,"牛哄哄的柯南6","某某省某某市6",new Date()));



        //List集合转换成 json


        String json = JSON.toJSONString(userList,   SerializerFeature.WriteDateUseDateFormat );


        System.out.println(json);

    }
}

运行结果：

[{"address":"某某省某某市1","date":"2020-12-17 21:09:21","id":1,"name":"牛哄哄的柯南1"},
{"address":"某某省某某市2","date":"2020-12-17 21:09:21","id":2,"name":"牛哄哄的柯南2"},
{"address":"某某省某某市3","date":"2020-12-17 21:09:21","id":3,"name":"牛哄哄的柯南3"},
{"address":"某某省某某市4","date":"2020-12-17 21:09:21","id":4,"name":"牛哄哄的柯南4"},
{"address":"某某省某某市5","date":"2020-12-17 21:09:21","id":5,"name":"牛哄哄的柯南5"},
{"address":"某某省某某市6","date":"2020-12-17 21:09:21","id":6,"name":"牛哄哄的柯南6"}]

Process finished with exit code 0

4.Controller代码

UserController代码：

package com.neuedu.controller;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.neuedu.entity.User;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
/**
 * Keafmd
 *
 * @ClassName: UserController
 * @Description: UserController
 * @author: 牛哄哄的柯南
 * @date: 2020-12-17 14:20
 *
 *
 *  http://127.0.0.1:8080/web/user
 */

@WebServlet(name="UserController" ,urlPatterns = "/user")
public class UserController extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        List userList = new ArrayList();
        userList.add(new User(1,"牛哄哄的柯南1","某某省某某市1",new Date()));
        userList.add(new User(2,"牛哄哄的柯南2","某某省某某市2",new Date()));
        userList.add(new User(3,"牛哄哄的柯南3","某某省某某市3",new Date()));
        userList.add(new User(4,"牛哄哄的柯南4","某某省某某市4",new Date()));
        userList.add(new User(5,"牛哄哄的柯南5","某某省某某市5",new Date()));
        userList.add(new User(6,"牛哄哄的柯南6","某某省某某市6",new Date()));

        String json = JSON.toJSONString(userList,   SerializerFeature.WriteDateUseDateFormat    );


        resp.setContentType("application/json");
        resp.setCharacterEncoding("utf-8");
        PrintWriter out = resp.getWriter();
        out.write(json);
        out.flush();
        out.close();

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req, resp);
    }
}

启动服务访问http://127.0.0.1:8080/web/user

访问结果：

OK,到此就完成实体类转为json对象的需求了。
 
 

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