@JsonFormat @DataTimeFormat 时间格式 入参 时间 日期 转换 Date_@datetimeformat(pattern = "yyyy-mm-dd")

省流：用@JsonFormat即可

一、时间格式

1. 字符串转Date

入参出参dto里，有时候会看到@DateTimeFormat或@JsonFormat，代码如下。

public class XXXdto{
 
    @DateTimeFormat(pattern = "yyyy-MM-dd")
    private Date startDate;
}
 
public class XXXdto{
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
    private Date startDate;
}

加@DateTimeFormat注解的目的：将字符串的时间转换成Date类型。此注解只能用于form表单请求和get请求。

加@JsonFormat注解的目的：将字符串的时间转换成Date类型。此注解只能用于json请求。在Controller层入参处需要用@RequestBody

补充：@DataTimeFormat用于前端传后端，@JsonFormat用于后端传前端，这种说法是错误的。@JsonFormat前传后、后传前都可以用。

使用方法：加在时间类型的变量上。

2. 时间格式不匹配

这是为了入参可以是日期时间格式(年月日时分秒)的值。如 {"startDate":"2022-01-01 01:02:02"}。

如果没有加注解@DateTimeFormat，会报错：

Invalid JSON input: 
Cannot deserialize value of type `java.util.Date` from String "2023-02-01 01:02:03": not a valid representation (error: Failed to parse Date value '2023-02-01 01:02:03': Cannot parse date "2023-02-01 01:02:03": while it seems to fit format 'yyyy-MM-dd'T'HH:mm:ss.SSSZ', parsing fails (leniency? null)); 
nested exception is com.fasterxml.jackson.databind.exc.InvalidFormatException: 
Cannot deserialize value of type `java.util.Date` from String "2023-02-01 01:02:03": not a valid representation (error: Failed to parse Date value '2023-02-01 01:02:03': Cannot parse date "2023-02-01 01:02:03": while it seems to fit format 'yyyy-MM-dd'T'HH:mm:ss.SSSZ', parsing fails (leniency? null))

根据报错信息，while it seems to fit format 'yyyy-MM-dd'T'HH:mm:ss.SSSZ'，判断传入的值日期格式有问题。

3. 正确的时间格式

正确时间格式：2023-02-01T00:00:00.000+0800，即前端传参： {"startDate":"2023-02-01T00:00:00.000+0800"}。

由于前端通常也是直接使用时间组件生成的值，时间组件生成的就是正确的时间格式，所以通常后端不需要加@DateTimeFormat。

但如果前端传的是自定义的值，例如：2023-01-01 01:01:01，即年月日时分秒，由于这个值不是正确的时间格式，这时候，后端没有加注解就会报错。

在没有注解的年代，会用SimpleDateFormat做转换。代码如下

public class XXXdto{
 
    private String startDate;
 
    public Date getStartDate(){
        return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse(startDate);
    }
}

但@DataTimeFormat不如@JsonFormat好用。另，如果值是纯日期，例如2022-01-01，也不需要用注解。

二、注解

1. @JsonFormat

com.fasterxml.jackson.annotation.JsonFormat;

public class XXXdto{
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
    private Date startDate;
}

@JsonFormat 默认的时区是 Greenwich Time， 格林威治时间，而我们是在东八区。查到的时间可能会比数据库中的时间少八个小时。所以需要加上timezone="GMT+8"

2. @DataTimeFormat

org.springframework.format.annotation.DateTimeFormat

public class XXXdto{
    @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    private Date startDate;
}

3. @JsonFormat 和 @DateTimeFormat 区别

三、补充：

1.前端传值给后端，后端接收到的都是字符串。

2.前端传日期格式的值，如果形如yyyy-MM-dd，即{"startDate":"2023-01-02"}，不需要用@DataTimeFormat和@JsonFormat，框架会帮你转。

四、自测

各种情况测试对比

报错1
Field error in object 'safescoreHomePageQueryParam' on field 'startTime': rejected value [2023-02-01 01:01:01];Failed to convert property value of type 'java.lang.String' to required type 'java.util.Date' for property 'endTime';nested exception is java.lang.IllegalArgumentException

报错2
nested exception is java.lang.IllegalArgumentException: Invalid format: "2023-02-01 01:01:01" is malformed at " 01:01:01"

使用@RequestBody，form表单提交会报错如下

Content type 'multipart/form-data;boundary=--------------------------590532731747110494187237;charset=UTF-8' not supported

使用@RequestBody，JSON提交，使用@JsonFormat，入参如果写20220101报错如下。

入参2022-01-01 10:01:01不会报错。时分秒写错不会报错

Invalid JSON input: Cannot deserialize value of type `java.util.Date` from String "20220101": expected format "yyyy-MM-dd"; nested exception is com.fasterxml.jackson.databind.exc.InvalidFormatException: Cannot deserialize value of type `java.util.Date` from String "20220101": expected format "yyyy-MM-dd"
 at [Source: (PushbackInputStream); line: 1, column: 14] (through reference chain: com.xxx.dto.xxx.xxxDTO["startTime"])

使用@RequestBody，JSON提交，不使用@JsonFormat，入参2022-01-01 10:01:01报错如下。入参2022-01-01不会报错。

Invalid JSON input: Cannot deserialize value of type `java.util.Date` from String "2022-01-01 10:01:01": not a valid representation (error: Failed to parse Date value '2022-01-01 10:01:01': Cannot parse date "2022-01-01 10:01:01": while it seems to fit format 'yyyy-MM-dd'T'HH:mm:ss.SSSZ', parsing fails (leniency? null)); nested exception is com.fasterxml.jackson.databind.exc.InvalidFormatException: Cannot deserialize value of type `java.util.Date` from String "2022-01-01 10:01:01": not a valid representation (error: Failed to parse Date value '2022-01-01 10:01:01': Cannot parse date "2022-01-01 10:01:01": while it seems to fit format 'yyyy-MM-dd'T'HH:mm:ss.SSSZ', parsing fails (leniency? null))
 at [Source: (PushbackInputStream); line: 1, column: 14] (through reference chain: com.xxx.dto.xxx.xxxDTO["startTime"])

参考

不要在听大坑们@DateTimeFormat 和 @JsonFormat只是前后端传参的区别了_*阿莫西林*的博客-CSDN博客

SpringBoot中时间格式化的5种方法！

=====================分割线=======================

文章到此已经结束，以下是紫薯布丁

public class XXXdto{

@DateTimeFormat(pattern = "yyyy-MM-dd")

private Date startDate;

}

public class XXXdto{

@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")

private Date startDate;

}

Invalid JSON input:

Cannot deserialize value of type `java.util.Date` from String "2023-02-01 01:02:03": not a valid representation (error: Failed to parse Date value '2023-02-01 01:02:03': Cannot parse date "2023-02-01 01:02:03": while it seems to fit format 'yyyy-MM-dd'T'HH:mm:ss.SSSZ', parsing fails (leniency? null));

nested exception is com.fasterxml.jackson.databind.exc.InvalidFormatException:

Cannot deserialize value of type `java.util.Date` from String "2023-02-01 01:02:03": not a valid representation (error: Failed to parse Date value '2023-02-01 01:02:03': Cannot parse date "2023-02-01 01:02:03": while it seems to fit format 'yyyy-MM-dd'T'HH:mm:ss.SSSZ', parsing fails (leniency? null))

public class XXXdto{

private String startDate;

public Date getStartDate(){

return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse(startDate);

}

}

public class XXXdto{

@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")

private Date startDate;

}

public class XXXdto{

@DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")

private Date startDate;

}

报错1

Field error in object 'safescoreHomePageQueryParam' on field 'startTime': rejected value [2023-02-01 01:01:01];Failed to convert property value of type 'java.lang.String' to required type 'java.util.Date' for property 'endTime';nested exception is java.lang.IllegalArgumentException

报错2

nested exception is java.lang.IllegalArgumentException: Invalid format: "2023-02-01 01:01:01" is malformed at " 01:01:01"

Content type 'multipart/form-data;boundary=--------------------------590532731747110494187237;charset=UTF-8' not supported

Invalid JSON input: Cannot deserialize value of type `java.util.Date` from String "20220101": expected format "yyyy-MM-dd"; nested exception is com.fasterxml.jackson.databind.exc.InvalidFormatException: Cannot deserialize value of type `java.util.Date` from String "20220101": expected format "yyyy-MM-dd"

at [Source: (PushbackInputStream); line: 1, column: 14] (through reference chain: com.xxx.dto.xxx.xxxDTO["startTime"])

Invalid JSON input: Cannot deserialize value of type `java.util.Date` from String "2022-01-01 10:01:01": not a valid representation (error: Failed to parse Date value '2022-01-01 10:01:01': Cannot parse date "2022-01-01 10:01:01": while it seems to fit format 'yyyy-MM-dd'T'HH:mm:ss.SSSZ', parsing fails (leniency? null)); nested exception is com.fasterxml.jackson.databind.exc.InvalidFormatException: Cannot deserialize value of type `java.util.Date` from String "2022-01-01 10:01:01": not a valid representation (error: Failed to parse Date value '2022-01-01 10:01:01': Cannot parse date "2022-01-01 10:01:01": while it seems to fit format 'yyyy-MM-dd'T'HH:mm:ss.SSSZ', parsing fails (leniency? null))

at [Source: (PushbackInputStream); line: 1, column: 14] (through reference chain: com.xxx.dto.xxx.xxxDTO["startTime"])