hibernate------->第一个程序

今天学习hibernate 。

创建User类：

package com.hibernate;

import java.util.Date;

public class User {
    private Integer id;
    private String name;
    private Date birth;
    
    public User(){}

    public User(Integer id, String name, Date birth) {
        super();
        this.id = id;
        this.name = name;
        this.birth = birth;
    }

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public Date getBirth() {
        return birth;
    }

    public void setBirth(Date birth) {
        this.birth = birth;
    }

    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + ", birth=" + birth + "]";
    }
    
}

写User类的hiebernate

<?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="com.hibernate">
     <!-- 映射表和实体 -->
     <class name="User" table="t_user">
         <!-- 字段(column)和属性(name)  属性名和字段名一致的时候，可以省略-->
         <id name="id">
         <!-- 主键生成器 -->
             <generator class="increment"></generator>
         </id>
         <property name="name"></property>
         <property name="birth"></property>
     </class>
 </hibernate-mapping>

配置hibernate的映射：

<?xml version="1.0" encoding="utf-8"?>
<!-- 
    dtd:document type definition
    标签,标签中的属性,标签的层级,标签的先后顺序
 -->
<!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>
        <!-- 配置信息 -->
        <!-- 数据库连接参数 -->
        <property name="hibernate.connection.url">jdbc:oracle:thin:@192.168.1.105:1521:orcl</property>
        <property name="hibernate.connection.driver_class">oracle.jdbc.OracleDriver</property>
        <property name="hibernate.connection.username">ems</property>
        <property name="hibernate.connection.password">123456</property>
        
        <!-- 自身配置信息
            dialect:方言   指示数据库的厂商.
                   :hibernate在进行底层的数据库操作时,会针对不同的数据库特点,做出相应的适应.
         -->
        <property name="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</property>
        <!-- 显示 并 格式化 hibernate底层执行的sql语句 -->
        <property name="hibernate.show_sql">true</property>
        <property name="hibernate.format_sql">true</property>
　　　　　　<!--在数据库中自动创建表-->
        <property name="hbm2ddl.auto">update</property>
        <!-- 映射文件的注册 -->
         <mapping resource="com/hibernate/User.hbm.xml"/>
        
    </session-factory>
</hibernate-configuration>

写测试类：

package com.hibernate;



import java.util.Date;

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


public class Test {
    public static void main(String[] args) {
        //加载配置
        Configuration config=new Configuration().configure();
        //用加载配置连接session工厂
        SessionFactory factory =config.buildSessionFactory();
        //利用session工厂创建session
        Session session=factory.openSession();
        //通过session获取事务
    Transaction transaction=session.beginTransaction();
    User u=new User(null,"heluwei",new Date());
        session.save(u);
        transaction.commit();
        session.close();
        factory.close();
    }
}

小知识：

getCurrentSession()和openSession()

用getCurrentSession()需要在xml文件中配置

<!--  即可通过getCurrentSession 获取线程唯一的session -->
        <property name="current_session_context_class">thread</property>
        <!-- 禁用了javaEE6的bean-validate -->
        <property name="javax.persistence.validation.mode">none</property>

openSession每次调用都获取新的session对象。但是getCurrentSession在同一线程中多次调用，获取的是同一个对象。

利用注解的方式：

在xml配置文件中需要加上需要注解的 类：

<mapping class="com.hibernate.User"/>

实体：

package com.hibernate;

import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;

import org.hibernate.annotations.GenericGenerator;

@Entity//这是一个参与ORM映射的实体
//参与ORM的表,及表名,如果表名和实体名一致的话,则此注解可以省略.
//则hibernate会用实体名作为表名
@Table(name="t_user")
public class User {
    //@Id必需注解
    @Id//此属性要映射主键列
    //如果属性名和列名一致,则@Column可以省略
    @Column(name="id")//此属性映射的列名为id
    @GenericGenerator(name="inc47",strategy="increment")
    @GeneratedValue(generator="inc47")
    private Integer id;
    //@Column(name="name")
    private String name;
    //@Column(name="birth")
    //Date==只保存日期
    //Time==只保存时间
    //TimeStamp==保存日期和时间 (默认)
    @Temporal(TemporalType.DATE)
    private Date birth;
    public User(){}

    public User(Integer id, String name, Date birth) {
        super();
        this.id = id;
        this.name = name;
        this.birth = birth;
    }

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public Date getBirth() {
        return birth;
    }

    public void setBirth(Date birth) {
        this.birth = birth;
    }

    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + ", birth=" + birth + "]";
    }
    
}