使用spring boot默认jackson映射时更改日期时区

在使用Spring Boot的默认Jackson映射时，可以通过以下几种方式来更改日期时区：

方法一：配置全局时区

在application.properties或application.yml文件中配置全局时区：

application.properties

spring.jackson.time-zone=GMT+8

application.yml

spring:
  jackson:
    time-zone: GMT+8

方法二：自定义ObjectMapper

创建一个配置类来自定义ObjectMapper，并设置时区：

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import org.springframework.boot.autoconfigure.jackson.Jackson2ObjectMapperBuilderCustomizer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.TimeZone;

@Configuration
public class JacksonConfig {

    @Bean
    public ObjectMapper objectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        mapper.setTimeZone(TimeZone.getTimeZone("GMT+8"));
        mapper.registerModule(new JavaTimeModule());
        mapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
        return mapper;
    }

    @Bean
    public Jackson2ObjectMapperBuilderCustomizer jsonCustomizer() {
        return builder -> {
            builder.timeZone("GMT+8");
        };
    }
}

方法三：使用注解

在实体类的日期字段上使用@JsonFormat注解来指定时区：

import com.fasterxml.jackson.annotation.JsonFormat;
import java.util.Date;

public class MyEntity {

    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
    private Date createTime;

    // getters and setters
}

方法四：配置消息转换器

通过配置Spring MVC的消息转换器来设置时区：

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import java.util.List;
import java.util.TimeZone;

@Configuration
public class WebConfig implements WebMvcConfigurer {

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.setTimeZone(TimeZone.getTimeZone("GMT+8"));
        objectMapper.registerModule(new JavaTimeModule());
        converter.setObjectMapper(objectMapper);
        converters.add(converter);
    }
}

通过以上几种方式，你可以灵活地控制Spring Boot应用中日期和时间的时区设置。选择最适合你项目需求的方法进行配置即可。