日期时间JPA映射

xiaoxiao2021-02-28  18

http://www.mamicode.com/info-detail-1519347.html

数据库日期时间类型

以MySQL为例,Date类型存储日期,Time类型存储时间,DateTime存储日期时间。对应的,这三个MySQL数据库字段类型在实体类的类型分别是java.sql.Date,java.sql.Time,java.sql.Timestamp。

Date类型

数据库表

在MySQL创建表student,字段CreateTime表示记录创建时间,仅仅存储时间。 CREATE TABLE `Student` ( `StudentId` bigint unsigned NOT NULL PRIMARY KEY AUTO_INCREMENT, `Name` varchar(100) NOT NULL, `CreateTime` date NOT NULL, PRIMARY KEY (`StudentId`), KEY `StudentName` (`Name`) ) ENGINE=InnoDB;

实体类

数据库表student的字段CreateTime是Date类型,对应的,实体类的属性createTime是java.sql.Date类型。 package com.gxz.entities; import java.sql.Date; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; @Entity @Table public class Student { private long id; private String name; private Date createTime; @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "StudentId") public long getId() { return id; } public void setId(long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Date getCreateTime() { return createTime; } public void setCreateTime(Date createTime) { this.createTime = createTime; } }

持久化

Student student = new Student(); student.setName("张三"); student.setCreateTime(new Date(new SimpleDateFormat("yyyy-MM-dd").parse("2016-01-01").getTime())); manager.persist(student);查看数据库表student的数据,如下所示。 若把持久化的时间代码修改成2016-01-01 01:01:01,持久化的效果依旧不会保存时间,因为字段CreateTime的Date类型只会保存日期,属性java.sql.Date类型只会保存日期。 Student student = new Student(); student.setName("张三"); student.setCreateTime(new Date(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse("2016-01-01 01:01:01").getTime())); manager.persist(student);持久化后,查看数据库表student的数据,如下所示。 若把数据库表student字段CreateTime的类型修改为DateTime,使之可以保存日期时间,但是,因为属性java.sql.Date类型只会保存日期,所以,该列的时间部分依旧全部为0。首先,我们修改数据库。 CREATE TABLE `Student` ( `StudentId` bigint unsigned NOT NULL PRIMARY KEY AUTO_INCREMENT, `Name` varchar(100) NOT NULL, `CreateTime` datetime NOT NULL, KEY `StudentName` (`Name`) ) ENGINE=InnoDB;持久化的时间代码如下所示。 student.setCreateTime(new Date(new SimpleDateFormat("yyyy-MM-dd").parse("2016-01-01").getTime())); 持久化后,查看数据库表student的数据,如下所示。 持久化的时间代码如下所示。 student.setCreateTime(new Date(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse("2016-01-01 01:01:01").getTime())); 持久化后,查看数据库表student的数据,如下所示。

DateTime类型

数据库表

把数据库表student字段CreateTime的类型修改为DateTime,使之可以保存日期时间。

实体类

数据库表student的字段CreateTime是DateTime类型,对应的,实体类的属性createTime是java.sql.Timestamp类型。 package com.gxz.entities; import java.sql.Timestamp; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; @Entity @Table public class Student { private long id; private String name; private Timestamp createTime; @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "StudentId") public long getId() { return id; } public void setId(long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Timestamp getCreateTime() { return createTime; } public void setCreateTime(Timestamp createTime) { this.createTime = createTime; } }

持久化

Student student = new Student(); student.setName("张三"); student.setCreateTime(new Timestamp(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse("2016-01-02 02:01:01").getTime())); manager.persist(student);持久化后,查看数据库表student的数据,如下所示。

Time类型

数据库表

把数据库表student字段CreateTime的类型修改为time,仅仅可以保存时间。 CREATE TABLE `Student` ( `StudentId` bigint unsigned NOT NULL PRIMARY KEY AUTO_INCREMENT, `Name` varchar(100) NOT NULL, `CreateTime` time NOT NULL, KEY `StudentName` (`Name`) ) ENGINE=InnoDB;

实体类

数据库表student的字段CreateTime是time类型,对应的,实体类的属性createTime是java.sql.Time类型。 package com.gxz.entities; import java.sql.Time; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; @Entity @Table public class Student { private long id; private String name; private Time createTime; @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "StudentId") public long getId() { return id; } public void setId(long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Time getCreateTime() { return createTime; } public void setCreateTime(Time createTime) { this.createTime = createTime; } }

持久化

Student student = new Student(); student.setName("张三"); student.setCreateTime(new Time(new SimpleDateFormat("HH:mm:ss").parse("02:01:01").getTime())); manager.persist(student);持久化后,查看数据库表student的数据,如下所示。

实体类属性是java.util.Calendar或java.util.Date

如果实体类属性是java.util.Calendar或java.util.Date,需要把这种类型转化为java.sql.Time、java.sql.Timestamp、java.sql.Date。实现转化的注解是javax.persistence.Temporal,该注解有一个属性javax.persistence.TemporalType,取值分别是TemporalType.DATE、TemporalType.TIME、TemporalType.TIMESTAMP。具体转化关系如下所述。 1.TemporalType.DATE:把java.util.Calendar或java.util.Date转化为java.sql.Date(持久化实体时),或把java.sql.Date转化为java.util.Calendar或java.util.Date(获取实体时)。 2.TemporalType.TIME:把java.util.Calendar或java.util.Date转化为java.sql.Time(持久化实体时),或把java.sql.TIME转化为java.util.Calendar或java.util.Time(获取实体时)。 3.TemporalType.TIMESTAMP:把java.util.Calendar或java.util.Date转化为java.sql.Timestamp(持久化实体时),或把java.sql.Timestamp转化为java.util.Calendar或java.util.Time(获取实体时)。

数据库表(DateTime类型)

数据库表student的字段CreateTime是DateTime类型。

实体类(Calendar类型)

实体类的属性是createTime的类型是java.util.Calendar,需要把java.util.Calendar转化为java.sql.Timestamp。 package com.gxz.entities; import java.util.Calendar; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; import javax.persistence.Temporal; import javax.persistence.TemporalType; @Entity @Table public class Student { private long id; private String name; private Calendar createTime; @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "StudentId") public long getId() { return id; } public void setId(long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @Temporal(TemporalType.TIMESTAMP) public Calendar getCreateTime() { return createTime; } public void setCreateTime(Calendar createTime) { this.createTime = createTime; } }

持久化(Calendar类型)

Student student = new Student(); student.setName("张三"); Calendar calendar = Calendar.getInstance(); calendar.setTime(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse("2016-05-12 12:25:23")); student.setCreateTime(calendar);持久化后,查看数据库表student的数据,如下所示。

数据库表(Date类型)

数据库表student的字段CreateTime是Date类型。

实体类(java.util.Date类型)

实体类的属性是createTime的类型是java.util.Date,需要把java.util.Date转化为java.sql.Date。 package com.gxz.entities; import java.util.Date; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; import javax.persistence.Temporal; import javax.persistence.TemporalType; @Entity @Table public class Student { private long id; private String name; private Date createTime; @Temporal(TemporalType.DATE) public Date getCreateTime() { return createTime; } public void setCreateTime(Date createTime) { this.createTime = createTime; } @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "StudentId") public long getId() { return id; } public void setId(long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } }

持久化(java.util.Date类型)

Student student = new Student(); student.setName("张三"); student.setCreateTime(new SimpleDateFormat("yyyy-MM-dd").parse("2016-05-13")); manager.persist(student); 持久化后,查看数据库表student的数据,如下所示。

日期时间JPA映射

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原文地址:http://blog.csdn.net/seedshome/article/details/52316913

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