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：
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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
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/** * 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 */@Embeddablepublic 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; } } |
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/** * 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。
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/** * 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; } } |
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/** * 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
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/** * 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; } } |
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/** * 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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原文链接：http://blog.csdn.net/wyc_cs/article/details/9031991
