ObjectMapper序列化时间

springmvc默认的消息转换器是使用的MappingJackson2HttpMessageConverter, 其核心类就是ObjectMapper.

先看一下面一个示例

@RestController
public class TestObjectMapperController {

    @GetMapping("/getUser")
    public User getUser() {
        User user = new User();
        user.setUId("1");
        user.setDate(new Date());
        user.setLocalDateTime(LocalDateTime.now());
        return user;
    }

}

@Data
class User {
    private String uId;
    private Date date;
    private LocalDateTime localDateTime;
}

启动springboot项目,浏览器请求/getUser接口,结果就是下面这个破样子

序列化后的时间格式明显不是我们想要的, 可以通过以下配置对其进行修改

@Configuration
public class ObjectMapperConfig {
    @Bean
    public Jackson2ObjectMapperBuilderCustomizer customJackson() {
        return jacksonObjectMapperBuilder -> {
            //若POJO对象的属性值为null，序列化时不进行显示
            jacksonObjectMapperBuilder.serializationInclusion(JsonInclude.Include.NON_NULL);

            //针对于Date类型，文本格式化
            jacksonObjectMapperBuilder.simpleDateFormat("yyyy-MM-dd HH:mm:ss");

            //针对于JDK新时间类。序列化时带有T的问题，自定义格式化字符串
            JavaTimeModule javaTimeModule = new JavaTimeModule();
            javaTimeModule.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")));
            jacksonObjectMapperBuilder.modules(javaTimeModule);

        };
    }
}

添加以下配置后, 重启项目,请求/getUser接口,结果如下

===============补充示例===============

public class TestObjectMapper {
    @Test
    public void test1() throws JsonProcessingException {
        ObjectMapper objectMapper = new ObjectMapper();
        //POJO无public的属性或方法时，不报错
        objectMapper.disable(SerializationFeature.FAIL_ON_EMPTY_BEANS);
        //null值字段不显示
        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        //美化JSON输出
        objectMapper.enable(SerializationFeature.INDENT_OUTPUT);

//        objectMapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);  // 序列化JSON串时，在值上打印出对象类型
        A a = new A();
        B b = new B();
        b.setSalary(100.5D);
        b.setAge(18);
        a.setB(b);
        a.setId("123");
        a.setUsername("admin");
        a.setDate(new Date());
        String string = objectMapper.writeValueAsString(a);   //解析对象
        System.out.println(string);
        
    }
}

@Data
class A {
    private String id;
    private String username;
    private Date date;
    private B b;
}

@Data
class B {
    private Double salary;
    private Integer age;
}