Annotation对Hibernate中联合主键定义

Annotation对Hibernate中联合主键定义

public class User {

private int id;

private String name;

private String address;

public int getId() {

return id;

}

public String getName() {

return name;

}

public String getAddress() {

return address;

}

public void setId(int id) {

this.id = id;

}

public void setName(String name) {

this.name = name;

}

public void setAddress(String address) {

this.address = address;

}

}

在如上类中假设需要定义一个联合主键 id,name，在hibernate中利用注解映射方法有如下三种：

1、将组件类注解为@Embeddable，并将实体类中组件的注解为@Id

      首先需要抽象出一个组件类，并将其注解为可嵌入式的Embeddedable在User中进行引用

@Embeddable

public class UserPk implements Serializable {

private static final long serialVersionUID = 1L;

private int id;

private String name;

public int getId() {

return id;

}

public String getName() {

return name;

}

public void setId(int id) {

this.id = id;

}

public void setName(String name) {

this.name = name;

}

}

其次要在实体类中将组件属性注解为@ID

@Entity

public class User {

private UserPk userPk;

private String address;

@Id

public UserPk getUserPk() {

return userPk;

}

public String getAddress() {

return address;

}

public void setUserPk(UserPk userPk) {

this.userPk = userPk;

}

public void setAddress(String address) {

this.address = address;

}

}

2、将组件的属性注解为@EmbeddedId

首先需要抽象出一个组件类，在User中进行引用

public class UserPk implements Serializable {

private static final long serialVersionUID = 1L;

private int id;

private String name;

public int getId() {

return id;

}

public String getName() {

return name;

}

public void setId(int id) {

this.id = id;

}

public void setName(String name) {

this.name = name;

}

}

其次需要在实体类中对组件属性注解为嵌入式的ID，即：@EmbeddedId

@Entity

public class User {

private UserPk userPk;

private String address;

@EmbeddedId

public UserPk getUserPk() {

return userPk;

}

public String getAddress() {

return address;

}

public void setUserPk(UserPk userPk) {

this.userPk = userPk;

}

public void setAddress(String address) {

this.address = address;

}

}

3、将类注解为@IdClass,并将该实体中所有属于主键属性都注解为@Id

抽象出组件类

public class UserPk implements Serializable {

private static final long serialVersionUID = 1L;

private int id;

private String name;

public int getId() {

return id;

}

public String getName() {

return name;

}

public void setId(int id) {

this.id = id;

}

public void setName(String name) {

this.name = name;

}

}

实体类

@Entity

@IdClass(value = UserPk.class)

public class User {

private int id;

private String name;

private String address;

@Id

public int getId() {

return id;

}

@Id

public String getName() {

return name;

}

public String getAddress() {

return address;

}

public void setId(int id) {

this.id = id;

}

public void setName(String name) {

this.name = name;

}

public void setAddress(String address) {

this.address = address;

}

}