可以將主鍵的資訊獨立為一個類別,例如:
- UserPK.java
package onlyfun.caterpillar;
import java.io.Serializable;
import org.apache.commons.lang.builder.EqualsBuilder;
import org.apache.commons.lang.builder.HashCodeBuilder;
public class UserPK implements Serializable {
private String name;
private String phone;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public boolean equals(Object obj) {
if(obj == this) {
return true;
}
if(!(obj instanceof User)) {
return false;
}
UserPK pk = (UserPK) obj;
return new EqualsBuilder()
.append(this.name, pk.getName())
.append(this.phone, pk.getPhone())
.isEquals();
}
public int hashCode() {
return new HashCodeBuilder()
.append(this.name)
.append(this.phone)
.toHashCode();
}
}
現在User類別的主鍵資訊被分離出來了,例如:
- User.java
package onlyfun.caterpillar;
import java.io.Serializable;
public class User implements Serializable {
private UserPK userPK; // 主鍵
private Integer age;
public User() {}
public UserPK getUserPK() {
return userPK;
}
public void setUserPK(UserPK userPK) {
this.userPK = userPK;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
}
在映射文件方面,需要指定主鍵類的資訊,例如:
- User.hbm.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping
PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="onlyfun.caterpillar.User" table="user">
<composite-id name="userPK"
class="onlyfun.caterpillar.UserPK"
unsaved-value="any">
<key-property name="name"
column="name"/>
<key-property name="phone"
column="phone"/>
</composite-id>
<property name="age" column="age"/>
</class>
</hibernate-mapping>
在查詢資料時,必須指定主鍵資訊,例如:
UserPK pk = new UserPK();
pk.setName("bush");
pk.setPhone("0970123456");
Session session = sessionFactory.openSession();
// 以主鍵類實例設定複合主鍵並載入對應的資料
User user = (User) session.load(User.class, pk);
System.out.println(user.getAge() + "\t" +
user.getUserPK().getName() + "\t" +
user.getUserPK().getPhone());
session.close();
pk.setName("bush");
pk.setPhone("0970123456");
Session session = sessionFactory.openSession();
// 以主鍵類實例設定複合主鍵並載入對應的資料
User user = (User) session.load(User.class, pk);
System.out.println(user.getAge() + "\t" +
user.getUserPK().getName() + "\t" +
user.getUserPK().getPhone());
session.close();