Hibernate---第一个helloworld程序 (XML版本, annotation版本)

Hibernate作为JPA的一种实现,jpa的注解已经是hibernate的核心，hibernate只提供了一些补充，而不是两套注解。hibernate对jpa的支持够足量，在使用hibernate注解建议使用jpa

XML版本过程:

新建工程, 导入hibernate包, 数据库包, 建立数据库表, 新建model类, 测试类, 新建src下hibernate.cfg.xml, model 类下 Student.hbm.xml

annotation版本过程:

新建工程, 导入hibernate包, 数据库包, 建立数据库表, 新建model类 (里面加入@Entity(javax), 和@Id (主键)), 测试类, 新建src下hibernate.cfg.xml(加入映射)

所以annotation比较简单.

XML版本具体过程:

1. new->java project : hibernate_0100_HelloWorld

2. 引入所有Hibernate的jar包:

　 1. preferrence->java->build path->user library-> new("hibernate")-> Add JARs (hibernate3, antlr, commons-collections, dom4j, javassist, jta,slf4j-api, slf4j-nop)

    2. 右键项目 build-> add libraries->user library->"hibernate"

3. 引入数据库包 build-> add external archieves-> mysql-connector....

4. 建立数据库的表    

create database hibernate;
use hibernate;
create table student(id int primary key, name varchar(20), age int);

5. new class: Student　   package: com.bjsxt.hibernate.model

package com.bjsxt.hibernate.model;

public class Student {
	private int id;
	private String name;
	private int age;
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
}

6.  new class: StudentTest.java     package: default

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

import com.bjsxt.hibernate.model.Student;


public class StudentTest {
	public static void main(String[] args) throws Exception{
		Student s =new Student();
		s.setId(2);
		s.setName("lisi");
		s.setAge(30);
		
		Configuration cfg=new Configuration();
		SessionFactory sf=cfg.configure().buildSessionFactory(); //默认找hibernate.cfg.xml,然后产生一个connection工厂
		Session session =  sf.openSession();
		session.beginTransaction();
		session.save(s);
		session.getTransaction().commit();
		session.close();
		sf.close();
	}
}

7. 在src下放hibernate.cfg.xml:

<?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">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost/hibernate</property>
        <property name="connection.username">root</property>
        <property name="connection.password">linda0213</property>
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>

        <!-- JDBC connection pool (use the built-in) -->
		<!--<property name="connection.pool_size">1</property> -->

        <!-- SQL dialect -->
		<property name="dialect">org.hibernate.dialect.MySQLDialect</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.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>
		<!--<property name="format_sql">true</property> -->

        <!-- Drop and re-create the database schema on startup
        <property name="hbm2ddl.auto">update</property>
		 -->
		<!--<mapping class="com.bjsxt.hibernate.model.Student"/> -->
        <mapping resource ="com/bjsxt/hibernate/model/Student.hbm.xml"/>		
    </session-factory>

</hibernate-configuration>

8. 在model下new Student.hbm.xml:

<?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="com.bjsxt.hibernate.model">
    <class name="Student" table="student">
        <id name="id"></id>
        <property name="name"/>
        <property name="age"/>
    </class>
</hibernate-mapping>

9. run -> java application.

运行出错的话一般还需要加入两个包: cglib-nodep-2.1_3.jar, commons-logging.jar

　　

annotation版本具体过程:

1. 加入annotation相关的jar包(hibernate-annotations, ejb3-persistence, hibernate-commons-annotations )

2. 创建teacher表:

use hibernate;
create table teacher(id int primary key, name varchar(20), title varchar(10));

3. 创建一个新的model 类, Teacher.java:

里面加入@Entity(javax), 和@Id (主键)

package com.bjsxt.hibernate.model;

import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class Teacher {
	private int id;
	private String name;
	private String title;
	
	@Id
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getTitle() {
		return title;
	}
	public void setTitle(String title) {
		this.title = title;
	}
}

3. 建立一个新的测试类TeacherTest.java;

import javax.persistence.Entity;

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

import com.bjsxt.hibernate.model.Teacher;

@Entity
public class TeacherTest {
	public static void main(String[] args) throws Exception{
		Teacher t =new Teacher();
		t.setId(3);
		t.setName("ww");
		t.setTitle("high");
		
		Configuration cfg=new AnnotationConfiguration();
		SessionFactory sf=cfg.configure().buildSessionFactory(); //默认找hibernate.cfg.xml,然后产生一个connection工厂
		Session session =  sf.openSession();
		session.beginTransaction();
		session.save(t);
		session.getTransaction().commit();
		session.close();
		sf.close();
	}
}

4. hibernate-cfg.xml里加入这句话:

<mapping class="com.bjsxt.hibernate.model.Teacher"/>

　　

　　

也可以自动创建数据库里的表, 只需要在hibernate.cfg.xml里加入这样一句话:

<property name="hbm2ddl.auto">create</property> 

可以通过类正向建表. 也可以建表反向推出类　

那么是先建表还是先建类呢?  理论上来说, 先建类, 但是实际工作中先表.

因为表需要进行优化,