JavaWeb实体类转为json对象

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;
}

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

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);
    }
}

[{"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

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);
    }
}