Hibernate初识

小配置里的代码：

<?xml version='1.0'  encoding='utf-8'?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="cn.happy.entity">
    <class name="Dog" table="Dog" >
        <id name="dogid" column="dogid">
            <generator class="native"></generator>//id主键  自增
        </id>
        <property name="dogname" column="dogname"></property>
        <property name="dogage" column="dogage" ></property>
    </class>

</hibernate-mapping>

　　实体类：

/**
 * Created by lgy on 2017/9/18.
 */
public class Dog {
    private String dogname;
    private Integer dogage;
    private Integer dogid;

    public String getDogname() {
        return dogname;
    }

    public void setDogname(String dogname) {
        this.dogname = dogname;
    }

    public Integer getDogage() {
        return dogage;
    }

    public void setDogage(Integer dogage) {
        this.dogage = dogage;
    }

    public Integer getDogid() {
        return dogid;
    }

    public void setDogid(Integer dogid) {
        this.dogid = dogid;
    }
}

　　util：

public class HibernateUntil {
    private static Configuration cfg=new Configuration().configure();
    private static SessionFactory factory=cfg.buildSessionFactory();

    //1.方法返回session  静态成员变量不能直接使用非静态成员
    //Session依赖于Session工厂，工厂依赖于Configure
    public static Session getSession(){
        return factory.openSession();

    }
    //2.关闭session
    public static void closeSession(){
        getSession().close();
    

　　大配置：

<?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>
        <!--数据库驱动-->
        <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
        <!--数据库url-->
        <property name="connection.url" >jdbc:oracle:thin:@localhost:1521:orcl</property>
        <!--数据库username-->
        <property name="connection.username" >test</property>
        <!--数据库password-->
        <property name="connection.password" >test</property>
        <!--hibernate方言--><!--和Spring整合时name属性前S必须加hibernate，单独用hibernate框架时，name属性可以直接用dialect-->
        <property name="hibernate.dialect" >org.hibernate.dialect.Oracle10gDialect</property>
        <!--输出所有语句到控制台-->
        <property name="hirbernate.show_sql" >true</property>
        <!--在log和console中打印出更新   格式化显示sql-->
        <property name="hibernate.format_sql" >true</property>
        <!--hbm2ddl就是**.hbm.xml,生成特定数据库的sql   从程序中自动建表 updata表示如果底层存在表，name更新表结构 -->
        <property name="hibernate.hbm2ddl.auto" >update</property>
        <!--指定当前session范围和上下文  thread至当前线程用来跟踪管理-->
        <property name="current_session_context_class" >thread</property>
        <mapping resource="cn/happy/entity/Dog.hbm.xml" ></mapping>
    </session-factory>
</hibernate-configuration>

　　Test测试类：

@Test
    public void testhibernate() {
        //configuration
        Configuration cfg=new Configuration().configure();
        SessionFactory factory=cfg.buildSessionFactory();
        Session session=factory.openSession();
        Transaction tx=session.beginTransaction();
        Dog dog=new Dog();
        dog.setDogname("小白");
        session.save(dog);
        tx.commit();
        System.out.println("add ok!");
        session.close();

    }

　　

//用get方法查询数据库
@Test
private void findStudent() {
    //02Hibernate 保存
    //读取大配置文件，获取连接的数据库信息
    Configuration cfg=new Configuration().configure();
    //3创建SessionFactory
    SessionFactory factory=cfg.buildSessionFactory();
    //加工session
    Session session=factory.openSession();
    //开启事务
    Transaction tx=session.beginTransaction();
    //5Hibernate
    //根据session的方法做数据操作  检索
    Student student=session.get(Student.class,2);
    System.out.println(student.getName());
    //提交事务
    tx.commit();
    //关闭session
    session.close();
    System.out.println("success  ok");
}

//用load方法查询
    @Test
    public void update2(){
        Configuration cfg=new Configuration().configure();
        SessionFactory factory=cfg.buildSessionFactory();
        Session session=factory.openSession();
        Transaction tx=session.beginTransaction();
        Dog dog=session.load(Dog.class,1);
        System.out.println("load-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=");
        System.out.println(dog.getDogname());
    }

　　load方法：

　　

无论get方法查询，还是load方法，都要开启事务，也不要手动提交！！！