坑之记录之@Temporal

本文深入探讨了@Temporal注解在Java应用中处理日期和时间的细节,解释了DATE、TIME和TIMESTAMP三种类型在数据库存储与页面返回值之间的转换规则。

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坑之记录之@Temporal

总的来说: 在某类中有Date类型的属性,数据库中存储可能是’yyyy-MM-dd hh:MM:ss’
@Temporal(TemporalType=DATE) 日期 “yyyy-MM-dd” 页面返回取值: 2016–09–28
@Temporal(TemporalType=TIME) 时间 “HH:MM:SS” 页面返回取值:15:50:30
@Temporal(TemporalType=TIMESTAMP) 两者兼具 页面返回取值:2016-09-28 15:52:32:000

### Java Temporal Annotation Usage and Examples In Java, temporal annotations play a crucial role when working with date-time APIs introduced in Java 8 under the `java.time` package. The primary purpose of these annotations is to provide metadata about how dates and times should be processed within applications. #### Commonly Used Annotations One common annotation related to temporal data handling is `@Temporal`. This annotation comes from JPA (Java Persistence API) rather than being part of standard Java libraries. It specifies that a persistent property or field should be persisted as a JDBC DATE, TIME, or TIMESTAMP depending on its value type[^1]. However, for more modern approaches using the `java.time` package directly without involving JPA, there isn't an official built-in annotation specifically named `@Temporal`. Instead, developers rely heavily upon method signatures and variable declarations leveraging classes like `LocalDate`, `LocalTime`, `ZonedDateTime`, etc., which inherently carry information regarding their intended usage context. For custom validation purposes outside persistence layers, frameworks such as Hibernate Validator offer annotations including: - `@Past`: Ensures the annotated element represents a point in time before now. - `@Future`: Validates whether the target date/time occurs after today's current timestamp. Example demonstrating basic application of these constraints can look similar to this snippet below written in Java code block format: ```java import javax.validation.constraints.Future; import java.time.LocalDate; public class Event { @Future(message = "Event must occur in future.") private LocalDate eventDate; // Getters & Setters omitted for brevity... } ``` This example ensures any instance created will only accept valid dates occurring sometime later relative to system clock at runtime evaluation moment. When integrating Spring Framework into projects, additional support becomes available through dedicated packages offering even richer set of options tailored towards web development scenarios where request parameters need validating against expected formats automatically during deserialization processes.
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