java hibernate使用注解来定义联合主键

2024-07-13 10:03:14

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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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