使用 jackson，完成json转对象，和对象转json串，包括日期处理

jackson的maven依赖

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.5.3</version>
</dependency>

使用的对象User

package com.dkp.bean;

import com.fasterxml.jackson.annotation.JsonFormat;

import java.util.Date;

/**
 * @author: dukangping
 * @Description:
 * @Date: Created in 2020/10/24 17:29
 */
public class User {

    private String userName;
    private Integer age;

	// 这里是设置时间的格式
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
    private Date birthday;

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    @Override
    public String toString() {
        return "User{" +
                "userName='" + userName + '\'' +
                ", age=" + age +
                ", birthday=" + birthday +
                '}';
    }
}

具体代码如下

package com.dkp.test;

import com.dkp.bean.User;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.List;

/**
 * @author: dukangping
 * @Description:
 * @Date: Created in 2020/10/24 17:28
 */
public class JsonToObject {
    
    public static void main(String[] args) throws JsonProcessingException {
        String json = "{\n" +
                "\t\"userName\": \"刘亦菲\",\n" +
                "\t\"age\": 30,\n" +
                "\t\"birthday\": \"2020-10-20 12:16:15\"\n" +
                "}";

        String josns = "[\n" +
                "\t{\n" +
                "\t\t\"userName\": \"刘亦菲\",\n" +
                "\t\t\"age\": 30,\n" +
                "\t\t\"birthday\": \"2020-10-01 12:16:15\"\n" +
                "\t},\n" +
                "\t{\n" +
                "\t\"userName\": \"李艺彤\",\n" +
                "\t\"age\": 20,\n" +
                "\t\"birthday\": \"2000-09-30 12:16:15\"\n" +
                "\t}\n" +
                "]";
        ObjectMapper objectMapper = new ObjectMapper();

        User user = null;
        List<User> users = null;
        try {
           // json字符串转换成对象
            user = objectMapper.readValue(json, User.class);
            // josn 字符串 转换成对象列表
            users = objectMapper.readValue(josns, new TypeReference<List<User>>() {
            });
        } catch (IOException e) {
            e.printStackTrace();
        }

        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
        String format = simpleDateFormat.format(user.getBirthday());

        System.out.println(user);
        System.out.println("----------------------------");

        users.forEach( (u) ->{
            System.out.println(u.toString());
        });

        /**
         * 对象转 json 字符串
         */
        System.out.println("对象转josn字符串----------------");
        String s = objectMapper.writeValueAsString(user);
        System.out.println(s);
        System.out.println();

        System.out.println("对象列表转字符串----------------");
        String ss = objectMapper.writeValueAsString(users);
        System.out.println(ss);
    }
}