联合主键--Annotation

原创 于 2011-06-02 12:23:38 发布 · 160 阅读 · 0 ·
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文章标签：

#Hibernate #junit #MySQL #JDBC #Cache

本文介绍了使用Hibernate框架配置联合主键的三种方法：通过@EmbeddedId注解组件类及属性；通过@EmbeddedId注解组件属性；以及使用@IdClass注解类，并配合@Id注解属性。文中还提供了详细的代码实例。

联合主键Annotation配置方法有三种：

1.将组件类注解为@EmbeddedId,并将组建的属性注解为@Id

2.将组件的属性注解为@EmbeddeId

3.将类注解为@IdClass,并将该实体中所有的主键的属性都注解为@Id

 

第一种：

1.定义注解类并其直接为@Embeddable

package com.zchen.hibernate.sxt.domain;

import java.io.Serializable;

import javax.persistence.Embeddable;

@Embeddable
public class StudentPK implements Serializable{
	private static final long serialVersionUID = -7880746333829652369L;
	private int id;
	private String name;
	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;
	}
	/*@Override
	public boolean equals(Object o){
		if(o instanceof StudentPK){
			StudentPK pk = (StudentPK)o;
			if(this.id == pk.getId() && this.name.equals(pk.getName())){
				return true;
			}
		}
		return false;
	}
	@Override
	public int hashCode(){
		return this.name.hashCode();
	}*/
	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + id;
		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;
		StudentPK other = (StudentPK) obj;
		if (id != other.id)
			return false;
		if (name == null) {
			if (other.name != null)
				return false;
		} else if (!name.equals(other.name))
			return false;
		return true;
	}

}

 2.定义实体类,将注解类放入其中并注解为@Id

package com.zchen.hibernate.sxt.domain;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="T_STUDENTS")
public class Students {
	private StudentPK pk;

	@Id
	public StudentPK getPk() {
		return pk;
	}

	public void setPk(StudentPK pk) {
		this.pk = pk;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

	private int age;

	private String address;

}

 3.定义Hibernate.cfg.xml配置文件

<?xml version="1.0"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
                                         "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
	<session-factory>
		 <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
		 <property name="connection.url">jdbc:mysql:///db_czbk_hibernate</property>
		 <property name="connection.username">root</property>
		 <property name="connection.password">1234</property>
		 <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
		 <property name="hbm2ddl.auto">create</property>
		 <property name="current_session_context_class">thread</property>
		 <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
		 <property name="show_sql">true</property>
		 <mapping class="com.zchen.hibernate.sxt.domain.Students"/>
		 
	</session-factory>
</hibernate-configuration>

 

4.测试：

package com.zchen.hibernate.sxt.test;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

import com.zchen.hibernate.sxt.domain.StudentPK;
import com.zchen.hibernate.sxt.domain.Students;


public class StudentsTest {
	
	private static SessionFactory sf = null;
	
	@BeforeClass
	public static void beforeClass(){
		try {
			sf = new AnnotationConfiguration().configure().buildSessionFactory();
		} catch (HibernateException e) {
			e.printStackTrace();
		}
	}
	
	@Test
	public void addStduentTest(){
		StudentPK pk = new StudentPK();
		pk.setId(2);
		pk.setName("chen");
		
		Students s = new Students();
		s.setAge(20);
		s.setAddress("湖南");
		s.setPk(pk);

		Session session = sf.getCurrentSession();
		session.beginTransaction();
		
		session.save(s);
		
		session.getTransaction().commit();
	}
	
	@AfterClass
	public static void afterClass(){
		if(sf != null){
			try {
				sf.close();
			} catch (HibernateException e) {
				e.printStackTrace();
			}
		}
	}


}

 

第二种：

1.定义主键类

package com.zchen.hibernate.sxt.domain;

import java.io.Serializable;

import javax.persistence.Embeddable;

//1.@Embeddable
public class StudentPK implements Serializable{
	private static final long serialVersionUID = -7880746333829652369L;
	private int id;
	private String name;
	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;
	}
	/*@Override
	public boolean equals(Object o){
		if(o instanceof StudentPK){
			StudentPK pk = (StudentPK)o;
			if(this.id == pk.getId() && this.name.equals(pk.getName())){
				return true;
			}
		}
		return false;
	}
	@Override
	public int hashCode(){
		return this.name.hashCode();
	}*/
	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + id;
		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;
		StudentPK other = (StudentPK) obj;
		if (id != other.id)
			return false;
		if (name == null) {
			if (other.name != null)
				return false;
		} else if (!name.equals(other.name))
			return false;
		return true;
	}

}

 2.定义实体类

package com.zchen.hibernate.sxt.domain;

import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="T_STUDENTS")
public class Students {
	private StudentPK pk;

	//@Id
	@EmbeddedId
	public StudentPK getPk() {
		return pk;
	}

	public void setPk(StudentPK pk) {
		this.pk = pk;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

	private int age;

	private String address;

}

 

 

第三种：

1.定义主键类：

package com.zchen.hibernate.sxt.domain;

import java.io.Serializable;

import javax.persistence.Embeddable;

public class StudentPK implements Serializable{
	private static final long serialVersionUID = -7880746333829652369L;
	private int id;
	private String name;
	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;
	}
	/*@Override
	public boolean equals(Object o){
		if(o instanceof StudentPK){
			StudentPK pk = (StudentPK)o;
			if(this.id == pk.getId() && this.name.equals(pk.getName())){
				return true;
			}
		}
		return false;
	}
	@Override
	public int hashCode(){
		return this.name.hashCode();
	}*/
	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + id;
		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;
		StudentPK other = (StudentPK) obj;
		if (id != other.id)
			return false;
		if (name == null) {
			if (other.name != null)
				return false;
		} else if (!name.equals(other.name))
			return false;
		return true;
	}

}

 

2.定义实体类：

package com.zchen.hibernate.sxt.domain;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.IdClass;
import javax.persistence.Table;

@Entity
@Table(name="T_STUDENTS")
@IdClass(value=StudentPK.class)
public class Students {
	/*private StudentPK pk;

	//@Id
	@EmbeddedId
	public StudentPK getPk() {
		return pk;
	}

	public void setPk(StudentPK pk) {
		this.pk = pk;
	}*/

	private int id;
	
	private String name;
	
	
	@Id
	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}
	@Id
	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

	private int age;

	private String address;

}

3.测试用例：

package com.zchen.hibernate.sxt.test;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

import com.zchen.hibernate.sxt.domain.StudentPK;
import com.zchen.hibernate.sxt.domain.Students;


public class StudentsTest {
	
	private static SessionFactory sf = null;
	
	@BeforeClass
	public static void beforeClass(){
		try {
			sf = new AnnotationConfiguration().configure().buildSessionFactory();
		} catch (HibernateException e) {
			e.printStackTrace();
		}
	}
	
	@Test
	public void addStduentTest(){
		/*StudentPK pk = new StudentPK();
		pk.setId(3);
		pk.setName("aaa");*/
		
		Students s = new Students();
		s.setId(4);
		s.setName("pig");
		s.setAge(20);
		s.setAddress("湖南");
		//s.setPk(pk);

		Session session = sf.getCurrentSession();
		session.beginTransaction();
		
		session.save(s);
		
		session.getTransaction().commit();
	}
	
	@AfterClass
	public static void afterClass(){
		if(sf != null){
			try {
				sf.close();
			} catch (HibernateException e) {
				e.printStackTrace();
			}
		}
	}


}

 

 

 

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