一个简单的利用hibernate实现增删改查的例子

下面这个例子非常简单，只是用于实现一个对oracle数据库中student表的一个简单的增删改查，其中查询和删除都是根据主键id来查询。
目录结构
图1：目录结构
hibernate.cfg.xml中的代码如下：
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
<property name="connection.url">jdbc:oracle:thin:@localhost:1521:orcl</property>
<property name="connection.username">yedward</property>
<property name="connection.password">yedward</property>
<property name="dialect">org.hibernate.dialect.OracleDialect</property>
<property name="show_sql">true</property>
<property name="format_sql">true</property>
<mapping resource="net/yedward/db/mapping/Student.hbm.xml" />
</session-factory>
</hibernate-configuration>
Student.hbm.xml中代码如下：
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="net.yedward.db.domain">
    <class name="Student" table="student">
        <id name="id" column="id"></id>
        <property name="name" column="name"></property>
        <property name="age" column="age"></property>
    </class>
</hibernate-mapping>
Student.java中的代码如下：
package net.yedward.db.domain;


import java.io.Serializable;


public class Student implements Serializable {
private static final long serialVersionUID = 5631142352656445262L;
private int id; // 注意在表中id是主键
private String name;
private int age;


public int getAge() {
return age;
}


public int getId() {
return id;
}


public String getName() {
return name;
}


public void setAge(int age) {
this.age = age;
}


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


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


}
StudentDAO.java中的代码如下：
package net.yedward.db.dao;


import net.yedward.db.domain.Student;


import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;


public class StudentDao {
// main方法，用于测试
public static void main(String[] args) {
delete(3);
}

// 增加
public static void add(Student student) {
Configuration cfg = new Configuration();
SessionFactory sf = cfg.configure().buildSessionFactory(); // 加载配置文件去构建Session工厂
Session session = sf.openSession();
session.beginTransaction();
session.save(student);
session.getTransaction().commit();
session.close();
sf.close();
}


// 查询，id是主键
public static Student findById(int id) {
Configuration cfg = new Configuration();
SessionFactory sf = cfg.configure().buildSessionFactory(); // 加载配置文件去构建Session工厂
Session session = sf.openSession();
// 查询不需要事务transaction
Student student = (Student) session.get(Student.class, id);
session.close();
sf.close();
return student;
}


// 修改
public static void update(Student student) {
Configuration cfg = new Configuration();
SessionFactory sf = cfg.configure().buildSessionFactory(); // 加载配置文件去构建Session工厂
Session session = sf.openSession();
session.beginTransaction();
session.update(student);
session.getTransaction().commit();
session.close();
sf.close();
}

// 删除
public static void delete(int id) {
Configuration cfg = new Configuration();
SessionFactory sf = cfg.configure().buildSessionFactory(); // 加载配置文件去构建Session工厂
Session session = sf.openSession();
session.beginTransaction();
Student student = new Student();
student.setId(id);
session.delete(student);
session.getTransaction().commit();
session.close();
sf.close();
}
}
上面的这些代码中，StudentDAO.java中的获得session的代码可以直接封装成一个工具类来调用，这里没有这样做了，以及hibernate的映射也可以用Annotation来写，这里也没这样做了，以后补充。