SpringBoot-LocalDateTime格式化处理

Java 8之后，日期类的处理建议使用java.time包中对应的LocalDateTime, LocalDate, LocalTime类。（参考Java8新特性）

在Spring Boot中（验证版本：2.1.5.RELEASE），日期类的序列化格式可能不是自己所希望的，需要定义为自己的格式。有两种方式实现。

注解方式

分别使用 @JsonFormat， @DateTimeFormat 来定义序列化（bean转json）与反序列（json转bean）时的格式

@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
@DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")
private LocalDateTime dateTime;

全局配置

定义一个配置类，对ObjectMapper对象进行定制，指定日期类对应的序列化与反序列化处理对象。

package com.example.config;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateDeserializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalTimeSerializer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;

@Configuration
public class LocalDateTimeFormatConfig {
    private static final String DEFAULT_DATE_TIME_PATTERN = "yyyy-MM-dd HH:mm:ss";
    private static final String DEFAULT_DATE_PATTERN = "yyyy-MM-dd";
    private static final String DEFAULT_TIME_PATTERN = "HH:mm:ss";

    @Bean
    @Primary
    //@Primary：自动装配时当出现多个Bean候选者时，被注解为@Primary的Bean将作为首选者，否则将抛出异常
    public ObjectMapper objectMapper(){
        ObjectMapper objectMapper = new ObjectMapper();
        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_PATTERN)));
        javaTimeModule.addSerializer(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_PATTERN)));
        javaTimeModule.addSerializer(LocalTime.class, new LocalTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_PATTERN)));
        javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_PATTERN)));
        javaTimeModule.addDeserializer(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_PATTERN)));
        javaTimeModule.addDeserializer(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_PATTERN)));
        objectMapper.registerModule(javaTimeModule);
        return objectMapper;
    }
}