java hibernate使用注解來定義聯合主鍵
下面使用hibernate的API中說明的三種方式來定義主鍵，主要使用Annotation來定義hibernate中的聯合主鍵
下面取至hibernate的API文檔：
定義組合主鍵的幾種語法：
1、將組件類注解為@Embeddable，并將組件的屬性注解為@Id
2、將組件的屬性注解為@EmbeddedId
3、將類注解為@IdClass，并將該實體中所有屬于主鍵的屬性都注解為@Id
下面就分別使用這三種方式來定義聯合主鍵。
建表的SQL語句：
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、將組件類注解為@Embeddable
/** * SysLogsDtoId代表主鍵類 */ package com.hibernate.dto; import javax.persistence.Embeddable; /** * 1、主鍵類必須要實現java.io.Serializable接口 * 2、主鍵類必須要重寫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為表對象映射類，其中主鍵為主鍵類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、將組件的屬性注解為@EmbeddedId
這種情況最簡單，主鍵類只用定義主鍵字段，不需要寫任何注解。然后在對象類中在主鍵類的get方法上加上@EmbeddedId注解。
/** * SysLogsDtoId代表主鍵類 */ 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為表對象映射類，其中主鍵為主鍵類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、將類注解為@IdClass，并將該實體中所有屬于主鍵的屬性都注解為@Id
/** * SysLogsDtoId代表主鍵類 */ 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為表對象映射類，其中主鍵為主鍵類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; } } 感謝閱讀，希望能幫助到大家，謝謝大家對本站的支持！
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