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 */@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;}}

/** * 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;}@Idpublic 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;}@EmbeddedIdpublic 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() {}@Idpublic String getId() {return id;}public void setId(String id) {this.id = id;}@Idpublic 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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