Hibernate annotation 一对一的两种实现:
1)幅表中有主表的主键ID做为引用
2)幅表的主键即为主表的ID
hibernate.cfg.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <!-- Database connection settings -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://127.0.0.1/testdb</property>
<property name="connection.username">root</property>
<property name="connection.password"></property> <!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">1</property> <!-- SQL dialect -->
<property name="dialect">org.hibernate.dialect.MySQL5Dialect</property> <!-- Enable Hibernate's automatic session context management -->
<property name="current_session_context_class">thread</property> <!-- Disable the second-level cache -->
<property name="cache.provider_class">org.hibernate.cache.internal.NoCacheProvider</property> <!-- Echo all executed SQL to stdout -->
<property name="show_sql">true</property> <!-- Drop and re-create the database schema on startup -->
<property name="hbm2ddl.auto">update</property> <mapping class="com.my.bean.User"/>
<mapping class="com.my.bean.UserCard"/>
<mapping class="com.my.bean.UserInfo"/> </session-factory> </hibernate-configuration>
HibernateUtil.java
package com.my.dao.util; import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration; public class HibernateUtil { private static final SessionFactory sessionFactory = buildSessionFactory(); private static SessionFactory buildSessionFactory() {
try {
// Create the SessionFactory from hibernate.cfg.xml
Configuration configuration = new Configuration();
return configuration.configure().buildSessionFactory(
new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build());
} catch (Throwable ex) {
// Make sure you log the exception, as it might be swallowed
System.err.println("Initial SessionFactory creation failed." + ex);
throw new ExceptionInInitializerError(ex);
}
} public static SessionFactory getSessionFactory() {
return sessionFactory;
} }
Java Beans:
package com.my.bean; import java.util.Date; import javax.persistence.*; @Entity
@Table(name="user")
public class User {
@Id @GeneratedValue @Column(name="user_id", nullable=false)
private long userID; @Column(name="user_name", length=100, nullable=false)
private String userName; @Column(name="create_time", nullable=false)
private Date createTime; @OneToOne(mappedBy="user")
private UserCard userCard; @OneToOne(cascade=CascadeType.ALL)
@PrimaryKeyJoinColumn
private UserInfo userInfo; public long getUserID() {
return userID;
} public void setUserID(long userID) {
this.userID = userID;
} public String getUserName() {
return userName;
} public void setUserName(String userName) {
this.userName = userName;
} public Date getCreateTime() {
return createTime;
} public void setCreateTime(Date createTime) {
this.createTime = createTime;
} public UserCard getUserCard() {
return userCard;
} public void setUserCard(UserCard userCard) {
this.userCard = userCard;
}
}
package com.my.bean; import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.Table; @Entity
@Table(name="user_card")
public class UserCard {
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="card_id", nullable=false)
private long cardID; @OneToOne
@JoinColumn(name="user_id")
private User user; @Column(name="card_name", nullable=false)
private String cardName; public long getCardID() {
return cardID;
}
public void setCardID(long cardID) {
this.cardID = cardID;
}
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
public String getCardName() {
return cardName;
}
public void setCardName(String cardName) {
this.cardName = cardName;
}
}
package com.my.bean; import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.Table; import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.Parameter; @Entity
@Table(name="user_info")
public class UserInfo {
@Id
@GeneratedValue(generator="userInfoForeignKey")
@GenericGenerator(name="userInfoForeignKey", strategy="foreign", parameters=@Parameter(name="property", value="user"))
@Column(name="user_id", nullable=false)
private long userID; @Column(name="message", nullable=false)
private String Message; @OneToOne(mappedBy="userInfo")
private User user; public long getUserID() {
return userID;
} public void setUserID(long userID) {
this.userID = userID;
} public String getMessage() {
return Message;
} public void setMessage(String message) {
Message = message;
} public User getUser() {
return user;
} public void setUser(User user) {
this.user = user;
}
}
测试:
package com.my.init;
import java.util.Date; import org.hibernate.Session;
import org.hibernate.Transaction; import com.my.bean.User;
import com.my.bean.UserCard;
import com.my.bean.UserInfo;
import com.my.dao.util.HibernateUtil; public class Test { public static void main(String[] args) {
Session session = HibernateUtil.getSessionFactory().openSession();
Transaction tx = session.beginTransaction(); try {
//---------------------------------------------------------
// The first method
//---------------------------------------------------------
// add user
User user = new User();
user.setUserName("Robin");
user.setCreateTime(new Date()); // add user card
UserCard userCard = new UserCard();
userCard.setCardName("BBC"); // add user card to user object
user.setUserCard(userCard);
userCard.setUser(user); //---------------------------------------------------------
// The second method
//---------------------------------------------------------
UserInfo userInfo = new UserInfo();
userInfo.setMessage("Message");
userInfo.setUser(user); //---------------------------------------------------------
// save
//---------------------------------------------------------
session.save(user);
session.save(userCard);
session.save(userInfo); tx.commit();
} catch (Exception e) {
tx.rollback();
e.printStackTrace();
} session.close();
} }