JPA联合主键的使用(@EmbeddedId+@Embeddable)

• 在用户角色权限设计中，我们使用复合主键来来保证唯一性
  

1.数据库

CREATE TABLE `sys_role_detail` (
  `roleid` int(11) DEFAULT NULL COMMENT '角色id',
  `menuid` int(11) DEFAULT NULL COMMENT '菜单id',
  `orgcode` varchar(20) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

2.实体类的联合主键

联合主键满足条件：
必须实现Serializable
必须有默认的 public无参数的构造方法、必须覆盖 equals和 hashCode 方法，这些要求与使用复合主键的要求相同
将嵌入式主键类使用 @Embeddable 标注，表示这个是一个嵌入式类。

package com.datalook.model;
import javax.persistence.Column;
import javax.persistence.Embeddable;
/**
 * SysRoleDetailId entity. 
 */
@SuppressWarnings("serial")
@Embeddable
public class SysRoleDetailId implements java.io.Serializable {
// Fields
private Integer roleid;
private Integer menuid;
// Constructors
/** default constructor */
public SysRoleDetailId() {
}
/** full constructor */
public SysRoleDetailId(Integer roleid, Integer menuid) {
this.roleid = roleid;
this.menuid = menuid;
}
// Property accessors
@Column(name = "roleid")
public Integer getRoleid() {
return this.roleid;
}
public void setRoleid(Integer roleid) {
this.roleid = roleid;
}
@Column(name = "menuid")
public Integer getMenuid() {
return this.menuid;
}
public void setMenuid(Integer menuid) {
this.menuid = menuid;
}
public boolean equals(Object other) {
if ((this == other))
return true;
if ((other == null))
return false;
if (!(other instanceof SysRoleDetailId))
return false;
SysRoleDetailId castOther = (SysRoleDetailId) other;
return ((this.getRoleid() == castOther.getRoleid()) || (this
.getRoleid() != null
&& castOther.getRoleid() != null && this.getRoleid().equals(
castOther.getRoleid())))
&& ((this.getMenuid() == castOther.getMenuid()) || (this
.getMenuid() != null
&& castOther.getMenuid() != null && this.getMenuid()
.equals(castOther.getMenuid())));
}
public int hashCode() {
int result = 17;
result = 37 * result
+ (getRoleid() == null ? 0 : this.getRoleid().hashCode());
result = 37 * result
+ (getMenuid() == null ? 0 : this.getMenuid().hashCode());
return result;
}
@Override
public String toString() {
return "SysRoleDetailId [roleid=" + roleid + ", menuid=" + menuid + "]";
}
}

3.实体

用@EmbeddedId和@AttributeOverrides 属性映射

package com.datalook.model;
import java.sql.Timestamp;
import javax.persistence.AttributeOverride;
import javax.persistence.AttributeOverrides;
import javax.persistence.Column;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.Table;
import javax.persistence.Transient;
import com.newcapec.model.AbstractDataLookModel;
/**
 * SysRoleDetail entity. @author MyEclipse Persistence Tools
 */
@Entity
@Table(name = "sys_role_detail")
public class SysRoleDetail extends AbstractDataLookModel {
 
    
    // Constructors
/** default constructor */
public SysRoleDetail() {
}
/** constructor */
public SysRoleDetail(SysRoleDetailId sysRoleDetailId) {
this.sysRoleDetailId = sysRoleDetailId;
}
private static final long serialVersionUID = -4244160679944459020L;
private SysRoleDetailId sysRoleDetailId;
private String orgcode;
// Property accessors
@Column(name = "orgcode", length = 32)
public String getOrgcode() {
return this.orgcode;
}
public void setOrgcode(String orgcode) {
this.orgcode = orgcode;
}
@EmbeddedId
@AttributeOverrides( {
@AttributeOverride(name = "roleid", column = @Column(name = "roleid")),
@AttributeOverride(name = "menuid", column = @Column(name = "menuid")) })
public SysRoleDetailId getSysRoleDetailId() {
return this.sysRoleDetailId;
}
public void setSysRoleDetailId(SysRoleDetailId sysRoleDetailId) {
this.sysRoleDetailId = sysRoleDetailId;
}
@Override
public String toString() {
return "SysRoleDetail [sysRoleDetailId=" + sysRoleDetailId + ", orgcode=" + orgcode + "]";
}
}