hibernate--组件映射

亦凉 2024-02-18 14:48 12阅读 0赞

组件映射：将一个对象属性组合到另外一个对象中（如两张表在数据库中组合成一张表），一个类中的属性包含另一个类的对象的引用

1、通过Annotation注解

Person.java:

package com.bean;
    
    import javax.persistence.Entity;
    import javax.persistence.Id;
    import javax.persistence.IdClass;
    import javax.persistence.OneToOne;
    
    public class Person {
    	private String wifeName;
    	private int age;
    
    	public int getAge() {
    		return age;
    	}
    
    	public void setAge(int age) {
    		this.age = age;
    	}
    
    	public String getWifeName() {
    		return wifeName;
    	}
    
    	public void setWifeName(String wifeName) {
    		this.wifeName = wifeName;
    	}
    }

PersonID.java:

package com.bean;
    
    import javax.persistence.Embedded;
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.Id;
    import javax.persistence.JoinColumn;
    import javax.persistence.JoinColumns;
    import javax.persistence.OneToOne;
    
    @Entity
    public class PersonID {
    	private int id;
    	private String name;
    	Person person;
    
    	@Id
    	@GeneratedValue
    	public int getId() {
    		return id;
    	}
    
    	public void setId(int id) {
    		this.id = id;
    	}
    
    	public String getName() {
    		return name;
    	}
    
    	public void setName(String name) {
    		this.name = name;
    	}
    
    	@Embedded
    	public Person getPerson() {
    		return person;
    	}
    
    	public void setPerson(Person person) {
    		this.person = person;
    	}
    
    }

cfg.xml文件中只需映射PersonId即可：

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE hibernate-configuration PUBLIC
            "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
            "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
    <hibernate-configuration>
       <session-factory>
         <property name="connection.driver_class">com.mysql.jdbc.Driver</property>    
         <property name="connection.url">jdbc:mysql://localhost:3306/user</property>     
         <property name="connection.username">root</property>   
         <property name="connection.password">root</property>
         
         <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
         <property name="show_sql">true</property>
         
         <property name="hbm2ddl.auto">update</property>
         <property name="show_sql">true</property>
         <property name="format_sql">true</property>  
         
         <property name="current_session_context_class">thread</property>
         <mapping class="com.bean.PersonID"/>
       </session-factory>
    </hibernate-configuration>

2、通过XML配置：

Husband.java:

package com.bean;
    
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.Id;
    import javax.persistence.OneToOne;
    
    public class Husband {
    	private int id;
    	private String name;
    	private Wife wife;
    
    
    	public int getId() {
    		return id;
    	}
    
    	public void setId(int id) {
    		this.id = id;
    	}
    
    	public String getName() {
    		return name;
    	}
    
    	public void setName(String name) {
    		this.name = name;
    	}
    
    	public Wife getWife() {
    		return wife;
    	}
    
    	public void setWife(Wife wife) {
    		this.wife = wife;
    	}
    
    }

Wife.java:

package com.bean;
    
    import javax.persistence.Entity;
    import javax.persistence.Id;
    
    public class Wife {
    	private String wifeName;
    	private int age;
    
    	public int getAge() {
    		return age;
    	}
    
    	public void setAge(int age) {
    		this.age = age;
    	}
    
    	public String getWifeName() {
    		return wifeName;
    	}
    
    	public void setWifeName(String wifeName) {
    		this.wifeName = wifeName;
    	}
    
    }

hbm.xml配置：

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE hibernate-mapping PUBLIC
            "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
            "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
    <hibernate-mapping>
      <class name = "com.bean.Husband" table = "Husband" >
    
         <id name = "id" column="id">
           <generator class="native"/>
         </id>
         <property name="name" />
         
         <component name="wife" >
           <property name="wifeName"/>
           <property name="age"/>
         </component>
      </class>
    </hibernate-mapping>

cfg.xml修改映射：