日期时间JPA映射
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。
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CREATETABLE`Student`(
`StudentId`bigintunsignedNOTNULLPRIMARYKEYAUTO_INCREMENT,
`Name`varchar(100)NOTNULL,
`CreateTime`dateNOTNULL,
PRIMARYKEY(`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。
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packagecom.gxz.entities;
importjava.sql.Date;
importjavax.persistence.Column;
importjavax.persistence.Entity;
importjavax.persistence.GeneratedValue;
importjavax.persistence.GenerationType;
importjavax.persistence.Id;
importjavax.persistence.Table;
@Entity
@Table
publicclassStudent{
privatelongid;
privateStringname;
privateDatecreateTime;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="StudentId")
publiclonggetId(){
returnid;
}
publicvoidsetId(longid){
this.id=id;
}
publicStringgetName(){
returnname;
}
publicvoidsetName(Stringname){
this.name=name;
}
publicDategetCreateTime(){
returncreateTime;
}
publicvoidsetCreateTime(DatecreateTime){
this.createTime=createTime;
}
}
持久化
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Studentstudent=newStudent();
student.setName("张三");
student.setCreateTime(newDate(newSimpleDateFormat("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2016-01-0101:01:01,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。
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Studentstudent=newStudent();
student.setName("张三");
student.setCreateTime(newDate(newSimpleDateFormat("yyyy-MM-ddHH:mm:ss").parse("2016-01-0101:01:01").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。
[sql]viewplaincopy
CREATETABLE`Student`(
`StudentId`bigintunsignedNOTNULLPRIMARYKEYAUTO_INCREMENT,
`Name`varchar(100)NOTNULL,
`CreateTime`datetimeNOTNULL,
KEY`StudentName`(`Name`)
)ENGINE=InnoDB;
持久化的时间代码如下所示。
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student.setCreateTime(newDate(newSimpleDateFormat("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。
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student.setCreateTime(newDate(newSimpleDateFormat("yyyy-MM-ddHH:mm:ss").parse("2016-01-0101:01:01").getTime()));
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。
[java]viewplaincopy
packagecom.gxz.entities;
importjava.sql.Timestamp;
importjavax.persistence.Column;
importjavax.persistence.Entity;
importjavax.persistence.GeneratedValue;
importjavax.persistence.GenerationType;
importjavax.persistence.Id;
importjavax.persistence.Table;
@Entity
@Table
publicclassStudent{
privatelongid;
privateStringname;
privateTimestampcreateTime;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="StudentId")
publiclonggetId(){
returnid;
}
publicvoidsetId(longid){
this.id=id;
}
publicStringgetName(){
returnname;
}
publicvoidsetName(Stringname){
this.name=name;
}
publicTimestampgetCreateTime(){
returncreateTime;
}
publicvoidsetCreateTime(TimestampcreateTime){
this.createTime=createTime;
}
}
持久化
[java]viewplaincopy
Studentstudent=newStudent();
student.setName("张三");
student.setCreateTime(newTimestamp(newSimpleDateFormat("yyyy-MM-ddHH:mm:ss").parse("2016-01-0202:01:01").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。
[sql]viewplaincopy
CREATETABLE`Student`(
`StudentId`bigintunsignedNOTNULLPRIMARYKEYAUTO_INCREMENT,
`Name`varchar(100)NOTNULL,
`CreateTime`timeNOTNULL,
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。
[java]viewplaincopy
packagecom.gxz.entities;
importjava.sql.Time;
importjavax.persistence.Column;
importjavax.persistence.Entity;
importjavax.persistence.GeneratedValue;
importjavax.persistence.GenerationType;
importjavax.persistence.Id;
importjavax.persistence.Table;
@Entity
@Table
publicclassStudent{
privatelongid;
privateStringname;
privateTimecreateTime;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="StudentId")
publiclonggetId(){
returnid;
}
publicvoidsetId(longid){
this.id=id;
}
publicStringgetName(){
returnname;
}
publicvoidsetName(Stringname){
this.name=name;
}
publicTimegetCreateTime(){
returncreateTime;
}
publicvoidsetCreateTime(TimecreateTime){
this.createTime=createTime;
}
}
持久化
[java]viewplaincopy
Studentstudent=newStudent();
student.setName("张三");
student.setCreateTime(newTime(newSimpleDateFormat("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。
[java]viewplaincopy
packagecom.gxz.entities;
importjava.util.Calendar;
importjavax.persistence.Column;
importjavax.persistence.Entity;
importjavax.persistence.GeneratedValue;
importjavax.persistence.GenerationType;
importjavax.persistence.Id;
importjavax.persistence.Table;
importjavax.persistence.Temporal;
importjavax.persistence.TemporalType;
@Entity
@Table
publicclassStudent{
privatelongid;
privateStringname;
privateCalendarcreateTime;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="StudentId")
publiclonggetId(){
returnid;
}
publicvoidsetId(longid){
this.id=id;
}
publicStringgetName(){
returnname;
}
publicvoidsetName(Stringname){
this.name=name;
}
@Temporal(TemporalType.TIMESTAMP)
publicCalendargetCreateTime(){
returncreateTime;
}
publicvoidsetCreateTime(CalendarcreateTime){
this.createTime=createTime;
}
}
持久化(Calendar类型)
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Studentstudent=newStudent();
student.setName("张三");
Calendarcalendar=Calendar.getInstance();
calendar.setTime(newSiwww.shanxiwang.netmpleDateFormat("yyyy-MM-ddHH:mm:ss").parse("2016-05-1212:25:23"));
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。
[java]viewplaincopy
packagecom.gxz.entities;
importjava.util.Date;
importjavax.persistence.Column;
importjavax.persistence.Entity;
importjavax.persistence.GeneratedValue;
importjavax.persistence.GenerationType;
importjavax.persistence.Id;
importjavax.persistence.Table;
importjavax.persistence.Temporal;
importjavax.persistence.TemporalType;
@Entity
@Table
publicclassStudent{
privatelongid;
privateStringname;
privateDatecreateTime;
@Temporal(TemporalType.DATE)
publicDategetCreateTime(){
returncreateTime;
}
publicvoidsetCreateTime(DatecreateTime){
this.createTime=createTime;
}
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="StudentId")
publiclonggetId(){
returnid;
}
publicvoidsetId(longid){
this.id=id;
}
publicStringgetName(){
returnname;
}
publicvoidsetName(Stringname){
this.name=name;
}
}
持久化(java.util.Date类型)
[java]viewplaincopy
Studentstudent=newStudent();
student.setName("张三");
student.setCreateTime(newSimpleDateFormat("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。
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