一. 场景描述

在进行前后端交互时，发现实体的LocalDateTime返回的格式是这样的：

这不符合我们日常习惯的格式 “年-月-日 时:分:秒”，于是上网学习了前辈
励碼的文章SSM项目中LocalDateTime格式化最佳实践_localdatetime 格式化-CSDN博客解决了问题。

二. 解决方案：

用到的和 jackson 相关的依赖有：

<!--	Json序列化（ObjectMapper）	-->
<dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.18.1</version>
</dependency>
<!--用于适配JAVA的时间类型（比如LocalDateTime）-->
<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.datatype/jackson-datatype-jsr310 -->
<dependency><groupId>com.fasterxml.jackson.datatype</groupId>	<artifactId>jackson-datatype-jsr310</artifactId><version>2.18.2</version>
</dependency>

2.1 创建配置类

千万别忘了注册 JavaTimeModule()，否则会报错转换不了 LocalDateTime类型

/*** @author yamu* @version 1.0* @description 配置响应的 Json 字符串的时间格式* @date 2025/1/24 9:54*/
@Configuration
public class JacksonConfig {public static final String DEFAULT_DATETIME_FORMAT = "yyyy-MM-dd HH:mm:ss";public static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd";public static final String DEFAULT_TIME_FORMAT = "HH:mm:ss";@Bean(name = "myObjectMapper")public ObjectMapper myObjectMapper() {ObjectMapper objectMapper = new ObjectMapper();//适用于java8的时间模块JavaTimeModule javaTimeModule = new JavaTimeModule();//年-月-日 时:分:秒DateTimeFormatter localDateTimeFormatter = DateTimeFormatter.ofPattern(DEFAULT_DATETIME_FORMAT);javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(localDateTimeFormatter));javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(localDateTimeFormatter));//年-月-日DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT);javaTimeModule.addSerializer(LocalDate.class, new LocalDateSerializer(dateFormatter));javaTimeModule.addDeserializer(LocalDate.class, new LocalDateDeserializer(dateFormatter));//时:分:秒DateTimeFormatter timeFormatter = DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT);javaTimeModule.addSerializer(LocalTime.class, new LocalTimeSerializer(timeFormatter));javaTimeModule.addDeserializer(LocalTime.class, new LocalTimeDeserializer(timeFormatter));//注册时间模块(不注册的话，会报错Java 8 date/time type `java.time.LocalDateTime` not supported by default: add Module "com.fasterxml.jackson.datatype:jackson-datatype-jsr310" to enable handling... )objectMapper.registerModule(javaTimeModule);// 配置其他特性objectMapper.setTimeZone(TimeZone.getTimeZone("GMT+8"));//设置东八区return objectMapper;}
}

2.2 在响应类中注册

这里有个注意点，由于我的响应类是通过R.success(T)去返回给前端的，所以自定义的ObjectMapper需要静态注入，但是@Autowired是不支持自动静态注入的，所以我定义了一个工具类去进行注入。

/*** @description: 自定义消息响应类* @author yamu* @date 2024/11/12 11:22* @version 1.0*/
@Data
public class R<T> {private Integer code; //0失败，1成功private String message; //错误信息private T data; //数据public static ObjectMapper objectMapper;//静态代码块注入JacksonConfig定义的objectMapperstatic{objectMapper =  ObjectMapperUtil.getObjectMapper();}/*** @description: 带返回值成功* @param: object* @returns:  R<T>* @author yamu* @date: 2024/11/12 11:24*/public static <T> String success(T object) {R<T> r = new R<T>();r.data = object;r.code = 1;try {return objectMapper.writeValueAsString(r);} catch (JsonProcessingException e) {throw new RuntimeException(e);}}
}

2.3 定义工具类静态注入ObjectMapper

/*** @author yamu* @version 1.0* @description 获取自定义序列化器的 ObjectMapper* @date 2025/1/24 17:06*/
@Component
public class ObjectMapperUtil implements ApplicationContextAware {private static ApplicationContext context;@Overridepublic void setApplicationContext(ApplicationContext applicationContext) throws BeansException {context = applicationContext;}public static ObjectMapper getObjectMapper() {return (ObjectMapper) context.getBean("myObjectMapper");}
}	public static ObjectMapper getObjectMapper() {return (ObjectMapper) context.getBean("myObjectMapper");}
}	

结果如下：