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为什么需要自定义Jackson序列化和反序列化?下面举个例子看看就知道了

问题描述

由于 Spring Boot 内置使用的就是 Jackson JSON 框架，所以，无需引入新的依赖，仅需添加自定义配置类即可，让其支持新的日期 API

Controller层的代码如下

@RestController
public class TestController {@PostMapping("/test2")public Response<User> test2(@RequestBody User user) {return Response.success(user);}
}

定义一个实体类User但是实体类含有LocalDateTime的日期类型

public class User {/*** 昵称*/private String nickName;/*** 创建时间*/private LocalDateTime createTime;
}

可以通过Postman这些工具来测试一下

下面是入参

{"nickName" : "小明","createTime": "2024-05-14 12:00:00"
}

你回发现一个问题就是，会报错

JSON parse error: Cannot deserialize value of type `java.time.LocalDateTime` from String "2024-05-14 12:00:00": Failed to deserialize java.time.LocalDateTime: (java.time.format.DateTimeParseException) Text '2024-05-14 12:00:00' could not be parsed at index 10]

提示我们 JSON 解析错误，无法将 2024-05-14 12:00:00 字符串解析为 java.time.LocalDateTime 日期类。

问题解决

需要自己定义一个配置类，覆盖框架本身的配置

@Configuration
public class JacksonConfig {@Beanpublic ObjectMapper objectMapper() {// 初始化一个 ObjectMapper 对象，用于自定义 Jackson 的行为ObjectMapper objectMapper = new ObjectMapper();// 忽略未知属性objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);objectMapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);// 设置时区objectMapper.setTimeZone(TimeZone.getTimeZone("Asia/Shanghai"));// JavaTimeModule 用于指定序列化和反序列化规则JavaTimeModule javaTimeModule = new JavaTimeModule();// 支持 LocalDateTime、LocalDate、LocalTimejavaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));javaTimeModule.addSerializer(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd")));javaTimeModule.addDeserializer(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd")));javaTimeModule.addSerializer(LocalTime.class, new LocalTimeSerializer(DateTimeFormatter.ofPattern("HH:mm:ss")));javaTimeModule.addDeserializer(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern("HH:mm:ss")));// 支持 YearMonthjavaTimeModule.addSerializer(YearMonth.class, new YearMonthSerializer(DateTimeFormatter.ofPattern("yyyy-MM")));javaTimeModule.addDeserializer(YearMonth.class, new YearMonthDeserializer(DateTimeFormatter.ofPattern("yyyy-MM")));objectMapper.registerModule(javaTimeModule);return objectMapper;}
}

完成之后,出入参实体类中就能支持定义 LocalDateTime 日期 API 了