[开发工具]jackson 常用方法

?DTO

package com.jt.dto;

import com.fasterxml.jackson.annotation.JsonProperty;
import lombok.Data;

/**
 * User: ldj
 * Date: 2022/3/6
 * Time: 2:01
 * Description: No Description
 */
@Data
public class UserDTO {
    private String name;

    private Integer age;

    @JsonProperty("class")
    private String clazz;
}

package com.jt.dto;

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

import java.util.List;
import java.util.Map;

/**
 * User: ldj
 * Date: 2022/3/5
 * Time: 22:09
 * Description: No Description
 */
public class JsonToObject {

    public static void main(String[] args) throws JsonProcessingException {

        String json = "{\"student\":[{\"name\": \"lili\",\"age\": 15,\"class1\": \"高三7班\"},{\"name\": \"ldj\",\"age\": 5,\"class1\": \"幼儿园\"},{\"name\": \"jack\",\"age\": 16,\"class1\": \"初三5班\"}]}";

        //jackson json -> Map
        ObjectMapper objectMapper = new ObjectMapper();

        Map<String, List<Object>> stringListMap1 = objectMapper.readValue(json, new TypeReference<Map<String, List<Object>>>() {
        });

        Map<String, Object> stringListMap2 = objectMapper.readValue(json, new TypeReference<Map<String, Object>>() {
        });

        System.out.println("jacksonMap1:" + stringListMap1);
        System.out.println("jacksonMap2:" + stringListMap2);

        //jackson json -> List
        String jsonBeans = "[{\"name\": \"lili\",\"age\": 15,\"class\": \"高三7班\"},{\"name\": \"ldj\",\"age\": 5,\"class\": \"幼儿园\"},{\"name\": \"jack\",\"age\": 16,\"class\": \"初三5班\"}]";

        //UsersDTO usersDTO = objectMapper.readValue(jsonBeans, UsersDTO.class); 数组类型 反序列失败了
        //System.out.println(usersDTO);

        List<Object> students = objectMapper.readValue(jsonBeans, new TypeReference<List<Object>>() {
        });

        System.out.println("jacksonList:" + students);

        String jsonBean = "{\"name\": \"lili\",\"age\": 15,\"class\": \"高三7班\"}";
        UserDTO userDTO = objectMapper.readValue(jsonBean, UserDTO.class);
        System.out.println(userDTO);
    }
}

反序列化失败的DTO

package com.jt.dto;

import java.util.List;

/**
 * User: ldj
 * Date: 2022/3/6
 * Time: 2:33
 * Description: No Description
 */
public class UsersDTO {
    public List<UserDTO> users;
}