JPA 联合主键

/**
 * 联合主键
 * 
 * 1、必须实现Serializable序列化 2、必须提示无参的构造方法 3、必须重写hashCode和equals方法
 * 
 * @Embeddable 表示该类中所有属性在应用该联合主键的类中作为它的属性（字段）
 * @author 张明学
 * 
 */

@Embeddable
public class AirLinePK implements Serializable {

	private String staCity;

	private String endCity;

	public AirLinePK() {

	}

	public AirLinePK(String staCity, String endCity) {
		this.staCity = staCity;
		this.endCity = endCity;
	}

	@Column(nullable = false, length = 32)
	public String getStaCity() {
		return staCity;
	}

	public void setStaCity(String staCity) {
		this.staCity = staCity;
	}

	@Column(nullable = false, length = 32)
	public String getEndCity() {
		return endCity;
	}

	public void setEndCity(String endCity) {
		this.endCity = endCity;
	}

	@Override
	public int hashCode() {
		final int PRIME = 31;
		int result = 1;
		result = PRIME * result + ((endCity == null) ? 0 : endCity.hashCode());
		result = PRIME * result + ((staCity == null) ? 0 : staCity.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;
		final AirLinePK other = (AirLinePK) obj;
		if (endCity == null) {
			if (other.endCity != null)
				return false;
		} else if (!endCity.equals(other.endCity))
			return false;
		if (staCity == null) {
			if (other.staCity != null)
				return false;
		} else if (!staCity.equals(other.staCity))
			return false;
		return true;
	}

}

 该联全主键的应用：

@Entity
@Table(name = "AIRLINE")
public class AirLineEntity {

	private AirLinePK a_id;

	private String a_name;

	// 联合主键
	@EmbeddedId
	public AirLinePK getA_id() {
		return a_id;
	}

	public void setA_id(AirLinePK a_id) {
		this.a_id = a_id;
	}

	@Column(length = 50)
	public String getA_name() {
		return a_name;
	}

	public void setA_name(String a_name) {
		this.a_name = a_name;
	}

}

 

测试：

public class CompositePKTest {
	@Test
	public void save(){
		EntityManagerFactory factory = Persistence.createEntityManagerFactory("mengya");
		EntityManager em = factory.createEntityManager();
		em.getTransaction().begin();
		
		AirLineEntity airLine = new AirLineEntity();
		airLine.setA_id(new AirLinePK("BeJing","ShangHai"));
		airLine.setA_name("北京至上海");
		
		em.persist(airLine);
		
		em.getTransaction().commit();
		em.close();
		factory.close();
	}
}

 

评论

1 楼 laccp 2012-12-11  

我在写一点，联合主键不能是内部类。