具有关联映射的Hibernate Composite ID

最近，我们面临着带有复合id字段的休眠关联映射的棘手情况。我们需要与一对一和多对一建立双向关联。我们的拖曳表是“ REPORT”和“ REPORT_SUMMARY”，它们之间具有从REPORT到REPORT_SUMMARY的一对多关系，而从REPORT_SUMMARY到REPORT表。 REPORT_SUMMARY表的主键定义为复合主键，它由自动增量id字段和REPORT表的主键组成。

CREATE TABLE REPORT (ID INT(10) NOT NULL AUTO_INCREMENT,NAME VARCHAR(45) NOT NULL,PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

CREATE TABLE REPORT_SUMMARY (ID INT(10) NOT NULL AUTO_INCREMENT,NAME VARCHAR(45) NOT NULL,RPT_ID INT(10) NOT NULL,PRIMARY KEY (`ID`,`RPT_ID`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

休眠实体类是休假的。
Report.java

package com.semika.autoac.entities;import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;
public class Report implements Serializable{private static final long serialVersionUID = 9146156921169669644L;private Integer id;private String name;private Set<ReportSummary> reportSummaryList  = new HashSet<ReportSummary>();public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Set<ReportSummary> getReportSummaryList() {return reportSummaryList;}public void setReportSummaryList(Set<ReportSummary> reportSummaryList) {this.reportSummaryList = reportSummaryList;}
}

ReportSummary.java

package com.semika.autoac.entities;import java.io.Serializable;
public class ReportSummary implements Serializable {private static final long serialVersionUID = 8052962961003467437L;private ReportSummaryId id;
private String name;public ReportSummaryId getId() {return id;
}
public void setId(ReportSummaryId id) {this.id = id;
}
public String getName() {return name;
}
public void setName(String name) {this.name = name;
}
@Override
public int hashCode() {final int prime = 31;int result = 1;result = prime * result + ((id == null) ? 0 : id.hashCode());result = prime * result + ((name == null) ? 0 : name.hashCode());return result;
}
@Override
public boolean equals(Object obj) {if (this == obj)return true;if (obj == null)return false;if (getClass() != obj.getClass())return false;ReportSummary other = (ReportSummary) obj;if (id == null) {if (other.id != null)return false;} else if (!id.equals(other.id))return false;if (name == null) {if (other.name != null)return false;} else if (!name.equals(other.name))return false;return true;}
}

ReportSummaryId.java

package com.semika.autoac.entities;import java.io.Serializable;public class ReportSummaryId implements Serializable{private static final long serialVersionUID = 6911616314813390449L;private Integer id;
private Report report;public Integer getId() {return id;
}
public void setId(Integer id) {this.id = id;
}
public Report getReport() {return report;
}
public void setReport(Report report) {this.report = report;
}
@Override
public int hashCode() {final int prime = 31;int result = 1;result = prime * result + ((id == null) ? 0 : id.hashCode());result = prime * result + ((report == null) ? 0 : report.hashCode());return result;
}
@Override
public boolean equals(Object obj) {if (this == obj)return true;if (obj == null)return false;if (getClass() != obj.getClass())return false;ReportSummaryId other = (ReportSummaryId) obj;if (id == null) {if (other.id != null)return false;} else if (!id.equals(other.id))return false;if (report == null) {if (other.report != null)return false;} else if (!report.equals(other.report))return false;return true;}
}

报表对象具有ReportSummary对象的集合，ReportSummaryId具有对Report对象的引用。此实现的最重要部分是休眠映射文件。 Report.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping><class name="com.semika.autoac.entities.Report" table="REPORT" ><id name="id" type="int" column="id" ><generator class="native"/></id><property name="name"><column name="NAME" /></property><set name="reportSummaryList" table="REPORT_SUMMARY" cascade="all" inverse="true"><key column="RPT_ID" not-null="true"></key><one-to-many class="com.semika.autoac.entities.ReportSummary"/></set></class>
</hibernate-mapping>

ReportSummary.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping><class name="com.semika.autoac.entities.ReportSummary" table="REPORT_SUMMARY" ><composite-id name="id" class="com.semika.autoac.entities.ReportSummaryId"><key-property name="id" column="ID"></key-property><key-many-to-one name="report" class="com.semika.autoac.entities.Report"column="RPT_ID"</key-many-to-one></composite-id><property name="name"><column name="NAME" /></property></class>
</hibernate-mapping>

参考： 如何在我们的JCG合作伙伴 Semika loku kaluge的Code Box博客上将Hibernate用于复合ID以及关联映射。