发布于 2018-02-24 01:54:08 | 70 次阅读 | 评论: 0 | 来源: 网友投递
Java程序设计语言
java 是一种可以撰写跨平台应用软件的面向对象的程序设计语言,是由Sun Microsystems公司于1995年5月推出的Java程序设计语言和Java平台(即JavaEE(j2ee), JavaME(j2me), JavaSE(j2se))的总称。
java hibernate使用注解来定义联合主键
下面使用hibernate的API中说明的三种方式来定义主键,主要使用Annotation来定义hibernate中的联合主键
下面取至hibernate的API文档:
定义组合主键的几种语法:
1、将组件类注解为@Embeddable,并将组件的属性注解为@Id
2、将组件的属性注解为@EmbeddedId
3、将类注解为@IdClass,并将该实体中所有属于主键的属性都注解为@Id
下面就分别使用这三种方式来定义联合主键。
建表的SQL语句:
CREATE TABLE `syslogs` (
`id` varchar(50) NOT NULL,
`yhid` varchar(50) NOT NULL,
`modelname` varchar(100) DEFAULT NULL,
`content` varchar(500) DEFAULT NULL,
`inserttime` varchar(20) DEFAULT NULL,
`remark` varchar(50) DEFAULT NULL,
PRIMARY KEY (`id`,`yhid`)
) ENGINE=InnoDB DEFAULT CHARSET=utf-8;
一、将组件类注解为@Embeddable
/**
* SysLogsDtoId代表主键类
*/
package com.hibernate.dto;
import javax.persistence.Embeddable;
/**
* 1、主键类必须要实现java.io.Serializable接口
* 2、主键类必须要重写equals和hashCode方法
* @author ibm
*/
@Embeddable
public class SysLogsDtoId implements java.io.Serializable {
private static final long serialVersionUID = 1L;
private String id;
private String yhid;
public SysLogsDtoId() {
}
public SysLogsDtoId(String id, String yhid) {
this.id = id;
this.yhid = yhid;
}
public String getId() {
return this.id;
}
public void setId(String id) {
this.id = id;
}
public String getYhid() {
return this.yhid;
}
public void setYhid(String yhid) {
this.yhid = yhid;
}
public boolean equals(Object other) {
if ((this == other))
return true;
if ((other == null))
return false;
if (!(other instanceof SysLogsDtoId))
return false;
SysLogsDtoId castOther = (SysLogsDtoId) other;
return ((this.getId() == castOther.getId()) || (this.getId() != null && castOther.getId() != null && this.getId().equals(castOther.getId())))
&& ((this.getYhid() == castOther.getYhid()) || (this.getYhid() != null && castOther.getYhid() != null && this.getYhid().equals(
castOther.getYhid())));
}
public int hashCode() {
int result = 17;
result = 37 * result + (getId() == null ? 0 : this.getId().hashCode());
result = 37 * result + (getYhid() == null ? 0 : this.getYhid().hashCode());
return result;
}
}
/**
* SysLogsDto为表对象映射类,其中主键为主键类SysLogsDtoId
*/
package com.hibernate.dto;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name = "syslogs")
public class SysLogsDto implements java.io.Serializable {
private static final long serialVersionUID = 1L;
private SysLogsDtoId id;
private String modelname;
private String content;
private String inserttime;
private String remark;
public SysLogsDto() {
}
public SysLogsDto(SysLogsDtoId id) {
this.id = id;
}
public SysLogsDto(SysLogsDtoId id, String modelname, String content, String inserttime, String remark) {
this.id = id;
this.modelname = modelname;
this.content = content;
this.inserttime = inserttime;
this.remark = remark;
}
@Id
public SysLogsDtoId getId() {
return this.id;
}
public void setId(SysLogsDtoId id) {
this.id = id;
}
@Column(name = "modelname", length = 100)
public String getModelname() {
return this.modelname;
}
public void setModelname(String modelname) {
this.modelname = modelname;
}
@Column(name = "content", length = 500)
public String getContent() {
return this.content;
}
public void setContent(String content) {
this.content = content;
}
@Column(name = "inserttime", length = 20)
public String getInserttime() {
return this.inserttime;
}
public void setInserttime(String inserttime) {
this.inserttime = inserttime;
}
@Column(name = "remark", length = 50)
public String getRemark() {
return this.remark;
}
public void setRemark(String remark) {
this.remark = remark;
}
}
二、将组件的属性注解为@EmbeddedId
这种情况最简单,主键类只用定义主键字段,不需要写任何注解。然后在对象类中在主键类的get方法上加上@EmbeddedId注解。
/**
* SysLogsDtoId代表主键类
*/
package com.hibernate.dto;
public class SysLogsDtoId implements java.io.Serializable {
private static final long serialVersionUID = 1L;
private String id;
private String yhid;
public SysLogsDtoId() {
}
public SysLogsDtoId(String id, String yhid) {
this.id = id;
this.yhid = yhid;
}
public String getId() {
return this.id;
}
public void setId(String id) {
this.id = id;
}
public String getYhid() {
return this.yhid;
}
public void setYhid(String yhid) {
this.yhid = yhid;
}
public boolean equals(Object other) {
if ((this == other))
return true;
if ((other == null))
return false;
if (!(other instanceof SysLogsDtoId))
return false;
SysLogsDtoId castOther = (SysLogsDtoId) other;
return ((this.getId() == castOther.getId()) || (this.getId() != null && castOther.getId() != null && this.getId().equals(castOther.getId())))
&& ((this.getYhid() == castOther.getYhid()) || (this.getYhid() != null && castOther.getYhid() != null && this.getYhid().equals(
castOther.getYhid())));
}
public int hashCode() {
int result = 17;
result = 37 * result + (getId() == null ? 0 : this.getId().hashCode());
result = 37 * result + (getYhid() == null ? 0 : this.getYhid().hashCode());
return result;
}
}
/**
* SysLogsDto为表对象映射类,其中主键为主键类SysLogsDtoId
*/
package com.hibernate.dto;
import javax.persistence.Column;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.Table;
@Entity
@Table(name = "syslogs")
public class SysLogsDto implements java.io.Serializable {
private static final long serialVersionUID = 1L;
private SysLogsDtoId id;
private String modelname;
private String content;
private String inserttime;
private String remark;
public SysLogsDto() {
}
public SysLogsDto(SysLogsDtoId id) {
this.id = id;
}
public SysLogsDto(SysLogsDtoId id, String modelname, String content, String inserttime, String remark) {
this.id = id;
this.modelname = modelname;
this.content = content;
this.inserttime = inserttime;
this.remark = remark;
}
@EmbeddedId
public SysLogsDtoId getId() {
return this.id;
}
public void setId(SysLogsDtoId id) {
this.id = id;
}
@Column(name = "modelname", length = 100)
public String getModelname() {
return this.modelname;
}
public void setModelname(String modelname) {
this.modelname = modelname;
}
@Column(name = "content", length = 500)
public String getContent() {
return this.content;
}
public void setContent(String content) {
this.content = content;
}
@Column(name = "inserttime", length = 20)
public String getInserttime() {
return this.inserttime;
}
public void setInserttime(String inserttime) {
this.inserttime = inserttime;
}
@Column(name = "remark", length = 50)
public String getRemark() {
return this.remark;
}
public void setRemark(String remark) {
this.remark = remark;
}
}
三、将类注解为@IdClass,并将该实体中所有属于主键的属性都注解为@Id
/**
* SysLogsDtoId代表主键类
*/
package com.hibernate.dto;
public class SysLogsDtoId implements java.io.Serializable {
private static final long serialVersionUID = 1L;
private String id;
private String yhid;
public SysLogsDtoId() {
}
public SysLogsDtoId(String id, String yhid) {
this.id = id;
this.yhid = yhid;
}
public String getId() {
return this.id;
}
public void setId(String id) {
this.id = id;
}
public String getYhid() {
return this.yhid;
}
public void setYhid(String yhid) {
this.yhid = yhid;
}
public boolean equals(Object other) {
if ((this == other))
return true;
if ((other == null))
return false;
if (!(other instanceof SysLogsDtoId))
return false;
SysLogsDtoId castOther = (SysLogsDtoId) other;
return ((this.getId() == castOther.getId()) || (this.getId() != null && castOther.getId() != null && this.getId().equals(castOther.getId())))
&& ((this.getYhid() == castOther.getYhid()) || (this.getYhid() != null && castOther.getYhid() != null && this.getYhid().equals(
castOther.getYhid())));
}
public int hashCode() {
int result = 17;
result = 37 * result + (getId() == null ? 0 : this.getId().hashCode());
result = 37 * result + (getYhid() == null ? 0 : this.getYhid().hashCode());
return result;
}
}
/**
* SysLogsDto为表对象映射类,其中主键为主键类SysLogsDtoId
*/
package com.hibernate.dto;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.IdClass;
import javax.persistence.Table;
@Entity
@Table(name = "syslogs")
@IdClass(value=SysLogsDtoId.class)
public class SysLogsDto implements java.io.Serializable {
private static final long serialVersionUID = 1L;
private String id;
private String yhid;
private String modelname;
private String content;
private String inserttime;
private String remark;
public SysLogsDto() {
}
@Id
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
@Id
public String getYhid() {
return yhid;
}
public void setYhid(String yhid) {
this.yhid = yhid;
}
@Column(name = "modelname", length = 100)
public String getModelname() {
return this.modelname;
}
public void setModelname(String modelname) {
this.modelname = modelname;
}
@Column(name = "content", length = 500)
public String getContent() {
return this.content;
}
public void setContent(String content) {
this.content = content;
}
@Column(name = "inserttime", length = 20)
public String getInserttime() {
return this.inserttime;
}
public void setInserttime(String inserttime) {
this.inserttime = inserttime;
}
@Column(name = "remark", length = 50)
public String getRemark() {
return this.remark;
}
public void setRemark(String remark) {
this.remark = remark;
}
}
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