hibernate之复合主键作为外键的相关配置

1.首先得有一个复合主键类CompositClassTest存在

CompositClassTest.java

package home.yhs.entity;

import java.io.Serializable;

public class CompositClassTest implements Serializable{

    /**
     * 
     */
    private static final long serialVersionUID = -1605112043060635015L;

    String classId;

    String className;

    public String getClassId() {
        return classId;
    }

    public void setClassId(String classId) {
        this.classId = classId;
    }

    public String getClassName() {
        return className;
    }

    public void setClassName(String className) {
        this.className = className;
    }

}

注意：该类不需要单独的配置文件

2.其次得的有一个包含复合主键类（CompositClassTest）的类ClassTest存在

ClassTest.java:

package home.yhs.entity;

public class ClassTest {

    CompositClassTest compositClassTest;//复合主键，用一个单独的类来表示
    
    String num;
    
    public CompositClassTest getCompositClassTest() {
        return compositClassTest;
    }

    public void setCompositClassTest(CompositClassTest compositClassTest) {
        this.compositClassTest = compositClassTest;
    }

    public String getNum() {
        return num;
    }

    public void setNum(String num) {
        this.num = num;
    }
    
}

对应的配置文件ClassTest.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="home.yhs.entity.ClassTest" table = "classtest"> 
           <composite-id name = "CompositClassTest" class = "home.yhs.entity.CompositClassTest">
               <key-property name="classId"></key-property>
               <key-property name="className"></key-property>//这部分就是对应复合主键类的相关配置
           </composite-id>
          <property name="num"></property>
    </class>  
</hibernate-mapping>

3.接下来有一个User.java类与对应的ClassTest类产生Many to one 的单向映射关系

User.java:

package home.yhs.entity;  
  
import java.util.Date;  
  
public class User {  
  
    private String id;  
    
    private String name;  
    
    private String password;  

　　private ClassTest classTest;//User类想要与ClassTest类达成单向映射的关系，必须包含ClassTest类的引用

    public User() {
        super();
    }
    
    public ClassTest getClassTest() {
        return classTest;
    }

    public void setClassTest(ClassTest classTest) {
        this.classTest = classTest;
    }

    public String getId() {  
        return id;  
    }  
    public void setId(String id) {  
        this.id = id;  
    }   
    public String getName() {  
        return name;  
    }   
    public void setName(String name) {  
        this.name = name;  
    }   
    public String getPassword() {  
        return password;  
    }   
    public void setPassword(String password) {  
        this.password = password;  
    }    

}

对应的配置文件User.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="home.yhs.entity.User" table = "User"> 
        <id name="id">  
            <generator class="assigned"/> 
        </id>  
        <property name="name"/>  
        <property name="password"/>  
        <many-to-one name="classTest" class="home.yhs.entity.ClassTest" cascade="all" unique="true" lazy="false">
        <column name="classId"></column>
        <column name="className"></column>
        </many-to-one> 
    </class>  
</hibernate-mapping>

4.最后再来一个测试类：

package home.yhs.util;

import java.util.Date;

import org.hibernate.Hibernate;

import home.yhs.entity.ClassTest;
import home.yhs.entity.CompositClassTest;
import home.yhs.entity.User;

public class Test {

    public static void main(String[] args) {
        CompositClassTest compositClassTest = new CompositClassTest();
        compositClassTest.setClassId("3");
        compositClassTest.setClassName("yhs");
        ClassTest clasTest = new ClassTest();
        clasTest.setCompositClassTest(compositClassTest);//添加复合主键到对应的类
        clasTest.setNum("234");
//        HibernateUtils.insert(clasTest);
        User user = new User();
        user.setId("2");
        user.setName("某某某");
        user.setPassword("root");
        user.setCreateTime(new Date());
        user.setExpireTime(new Date());
        user.setClassTest(clasTest);
        HibernateUtils.insert(user); 
    /*    User user = new User();
        user.setId("4");
        User user1 = (User) HibernateUtils.getById(User.class, user.getId());
        System.out.println(user1.getClassTest().getNum());*/
    }

}

注意：在实现User与ClassTest的单映射之后，在User执行插入操作的时候，会先到ClassTest对应的数据表中查找User对应的复合外键的数据行是否存在，如果存在则不再插入，如果不存在，则会先向ClassTest表中插入数据，然后再向User表中插入数据。