JPA视频学习(六)联合主键

1.配置主键类

import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Embeddable;

/**
 * 1.提供无参数构造器
 * 2.实现序列号接口
 * 3.重写hashCode和equals方法
 * @author Administrator
 *
 */
@Embeddable //用在实体里面，告诉JPA只是使用该类里面的属性作为持久化字段
public class AirLinePK implements Serializable{

	private String startCityString;//北京PEK
	private String endCityString;
	
	public AirLinePK(){} 
	
	
	public AirLinePK(String endCityString, String startCityString) {
		
		this.endCityString = endCityString;
		this.startCityString = startCityString;
	}


	@Column(length=3)
	public String getStartCityString() {
		return startCityString;
	}
	public void setStartCityString(String startCityString) {
		this.startCityString = startCityString;
	}
	
	@Column(length=3)
	public String getEndCityString() {
		return endCityString;
	}
	public void setEndCityString(String endCityString) {
		this.endCityString = endCityString;
	}
	
	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result
				+ ((endCityString == null) ? 0 : endCityString.hashCode());
		result = prime * result
				+ ((startCityString == null) ? 0 : startCityString.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;
		AirLinePK other = (AirLinePK) obj;
		if (endCityString == null) {
			if (other.endCityString != null)
				return false;
		} else if (!endCityString.equals(other.endCityString))
			return false;
		if (startCityString == null) {
			if (other.startCityString != null)
				return false;
		} else if (!startCityString.equals(other.startCityString))
			return false;
		return true;
	}
	
	
	
}

2.配置实体bean

import javax.persistence.Column;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;

@Entity
public class AirLine {

	private AirLinePK id;
	private String name;
	
	
	public AirLine() {
		// TODO Auto-generated constructor stub
	}

	
    public AirLine(String endCityString, String startCityString, String name) {
		
    	this.id=new AirLinePK(startCityString,endCityString);
    	this.name = name;
	}


	@EmbeddedId //为实体的id
	public AirLinePK getId() {
		return id;
	}


	public void setId(AirLinePK id) {
		this.id = id;
	}

    @Column(length=20)
	public String getName() {
		return name;
	}


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

	
}

3.Junit测试

package junit.test;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import org.junit.BeforeClass;
import org.junit.Test;
import com.persia.bean.AirLine;
import com.persia.bean.AirLinePK;
import com.sun.org.apache.bcel.internal.generic.NEW;

public class CompositePKTest {

	@BeforeClass
	public static void setUpBeforeClass() throws Exception {
	}
   
	//@Test
	public void save(){
		EntityManagerFactory factory=Persistence.createEntityManagerFactory("JPACompositePKPU");
		EntityManager entityManager=factory.createEntityManager();
		entityManager.getTransaction().begin();
		 entityManager.persist(new AirLine("PEK","SHA","北京飞往上海"));
		entityManager.getTransaction().commit();
		entityManager.close();
		factory.close();
	}
	
	//@Test
	public void getAirLine(){
		EntityManagerFactory factory=Persistence.createEntityManagerFactory("JPACompositePKPU");
		EntityManager entityManager=factory.createEntityManager();
		//entityManager.getTransaction().begin();
		AirLine aLine=entityManager.find(AirLine.class, new AirLinePK("SHA","PEK"));
		System.out.println("查询出来的航线："+aLine.getName());
		//entityManager.getTransaction().commit();
		entityManager.close();
		factory.close();
	}
	
	//@Test
	public void updateAirLine(){
		EntityManagerFactory factory=Persistence.createEntityManagerFactory("JPACompositePKPU");
		EntityManager entityManager=factory.createEntityManager();
		entityManager.getTransaction().begin();
		  AirLine aLine=entityManager.find(AirLine.class, new AirLinePK("SHA","PEK"));
		  aLine.setName("bj-sh");
		  aLine.setId(new AirLinePK("sh","bj"));//主键无法修改
		  entityManager.merge(aLine);
		entityManager.getTransaction().commit();
		entityManager.close();
		factory.close();
	}
	
	@Test
	public void deleteAirLine(){
		EntityManagerFactory factory=Persistence.createEntityManagerFactory("JPACompositePKPU");
		EntityManager entityManager=factory.createEntityManager();
		entityManager.getTransaction().begin();
		  AirLine aLine=entityManager.find(AirLine.class, new AirLinePK("SHA","PEK"));
		  entityManager.remove(aLine);
		entityManager.getTransaction().commit();
		entityManager.close();
		factory.close();
	}
}