1、工具类

package com.atguigu.utils;import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;import java.io.IOException;
import java.text.SimpleDateFormat;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.List;import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;/*** 基于Jackson的JSON转换工具类** @author: XuXin* @date: 2023/9/18*/
@Slf4j
public class JsonUtils {// 定义jackson对象private static final ObjectMapper objectMapper = new ObjectMapper();static {// 对象的所有字段全部列入，还是其他的选项，可以忽略null等objectMapper.setSerializationInclusion(JsonInclude.Include.ALWAYS);// 设置Date类型的序列化及反序列化格式objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));// 忽略空Bean转json的错误objectMapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);// 忽略未知属性，防止json字符串中存在，java对象中不存在对应属性的情况出现错误objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);// 注册一个时间序列化及反序列化的处理模块，用于解决jdk8中localDateTime等的序列化问题objectMapper.registerModule(new JavaTimeModule().addSerializer(LocalDateTime.class,new LocalDateTimeSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"))).addDeserializer(LocalDateTime.class,new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"))));}/*** 对象 => json字符串** @param obj 源对象*/public static String format(Object obj) {String json = null;if (obj != null) {try {json = objectMapper.writeValueAsString(obj);} catch (JsonProcessingException e) {log.warn(e.getMessage(), e);throw new IllegalArgumentException(e.getMessage());}}return json;}/*** json字符串 => 对象** @param jsonStr 源json串* @param clazz   对象类* @param <T>     泛型*/public static <T> T parse(String jsonStr, Class<T> clazz) {return parse(jsonStr, clazz, null);}/*** json字符串 => 对象** @param jsonStr 源json串* @param type    对象类型* @param <T>     泛型*/public static <T> T parse(String jsonStr, TypeReference<T> type) {return parse(jsonStr, null, type);}/*** json => 对象处理方法* <br>* 参数clazz和type必须一个为null，另一个不为null* <br>* 此方法不对外暴露，访问权限为private** @param jsonStr 源json串* @param clazz   对象类* @param type    对象类型* @param <T>     泛型*/private static <T> T parse(String jsonStr, Class<T> clazz, TypeReference<T> type) {T obj = null;if (!StringUtils.isEmpty(jsonStr)) {try {if (clazz != null) {obj = objectMapper.readValue(jsonStr, clazz);} else {obj = objectMapper.readValue(jsonStr, type);}} catch (IOException e) {log.warn(e.getMessage(), e);throw new IllegalArgumentException(e.getMessage());}}return obj;}public static <T> List<T> json2List(String jsonStr, Class<T> beanType) {JavaType javaType = objectMapper.getTypeFactory().constructParametricType(ArrayList.class, beanType);try {List<T> list = objectMapper.readValue(jsonStr, javaType);return list;} catch (Exception e) {e.printStackTrace();}return null;}}

2、使用

@SpringBootTest
class MybatisplusApplicationTests {@Testvoid contextLoads() throws IOException {User user = new User();user.setName("pp");user.setAge(17);String s = JsonUtils3.format(user);User user1 = JsonUtils3.parse(s, User.class);User user2 = JsonUtils3.parse(s, new TypeReference<User>() {});Map<String, String> map = JsonUtils3.parse(s, new TypeReference<Map<String, String>>() {});String s2 = "[\n" +"{\"id\": 1, \"name\": \"John\"},\n" +"{\"id\": 2, \"name\": \"Jane\"},\n" +"{\"id\": 3, \"name\": \"Bob\"}\n" +"]";String s3 = "[{\"id\":null,\"name\":\"pp\",\"age\":17,\"email\":null,\"persion\":null}]";List<User> users1 = JsonUtils3.json2List(s2, User.class);List<User> users2 = JsonUtils3.json2List(s3, User.class);}
}

s:
{“id”:null,“name”:“pp”,“age”:17,“email”:null,“persion”:null}
s2:
[
{“id”: 1, “name”: “John”},
{“id”: 2, “name”: “Jane”},
{“id”: 3, “name”: “Bob”}
]
s3:
[{“id”:null,“name”:“pp”,“age”:17,“email”:null,“persion”:null}]