Hibernate基础

package com.alfred.bean;

import java.sql.Date;

public class Person {
	private Long id;
	private String username;
	private Integer age;
	private Date birthday;

	public Person() {
	}

	public Person(String username, int age, Date birthday) {
		this.username = username;
		this.age = age;
		this.birthday = birthday;
	}

	public Long getId() {
		return id;
	}

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

	public String getUsername() {
		return username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public Integer getAge() {
		return age;
	}

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

	public Date getBirthday() {
		return birthday;
	}

	public void setBirthday(Date birthday) {
		this.birthday = birthday;
	}

}

package com.alfred.bean;

import java.sql.Timestamp;

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

import org.hibernate.annotations.GenericGenerator;

@Entity
@Table(name = "employee")
public class Employee {
	private Long id;
	private String fullname;
	private Integer workyear;
	private Timestamp employdate;

	public Employee() {
	}

	public Employee(String fullname, Integer workyear, Timestamp employdate) {
		this.fullname = fullname;
		this.workyear = workyear;
		this.employdate = employdate;
	}

	@GenericGenerator(name = "generator", strategy = "increment")
	@Id
	@GeneratedValue(generator = "generator")
	@Column(name = "id", unique = true, nullable = false)
	public Long getId() {
		return id;
	}

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

	@Column(name = "fullname", length = 32)
	public String getFullname() {
		return fullname;
	}

	public void setFullname(String fullname) {
		this.fullname = fullname;
	}

	@Column(name = "workyear")
	public Integer getWorkyear() {
		return workyear;
	}

	public void setWorkyear(Integer workyear) {
		this.workyear = workyear;
	}

	@Column(name = "employ_date")
	public Timestamp getEmploydate() {
		return employdate;
	}

	public void setEmploydate(Timestamp employdate) {
		this.employdate = employdate;
	}

}

<?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>一般不去配置,采用默认即可
default-cascade="none":默认的级联风格,表与表联动.
default-lazy="true":默认延迟加载
 -->
<hibernate-mapping>
	<!--
        <class>:使用class元素定义一个持久化类.
        name="com.alfred.bean.Person":持久化类的java全限定名;
        table="person":对应数据库表名;
        mutable="true":默认为true,设置为false时则不可以被应用程序更新或删除;
        dynamic-insert="false":默认为false,动态插入非空值字段;
        dynamic-update="false":默认为false,动态修改那些有改变过的字段,而不用修改所有字段;
        select-before-update="false":默认为false,在修改之前先做一次查询,与用户的值进行对比,有变化都会真正更新;
        optimistic-lock="version":默认为version(检查version/timestamp字段),取值:all(检查全部字段)、dirty(只检查修改过的字段)、
                                   none(不使用乐观锁定),此参数主要用来处理并发,每条值都有固定且唯一的版本,版本为最新时才能执行操作;
     -->
    <class name="com.alfred.bean.Person" table="person">
    	<!--
            <id>:定义了该属性到数据库表主键字段的映射.
            name="id":标识属性的名字;
            column="id":表主键字段的名字,如果不填写与name一样;
         -->
        <id name="id" column="id">
        	<!--
        	<generator>:指定主键由什么生成.
        	例如:
        	uuid:唯一标识符.
        		(32位,长度大,占用空间大,跨数据库,不用访问数据库就生成主键值,所以效率高且能保证唯一性,移植非常方便,推荐使用.)
        	native:由hibernate根据使用的数据库自行判断采用identity、hilo、sequence其中一种作为主键生成方式，灵活性很强。如果能支持identity则使用identity，如果支持sequence则使用sequence.
        		(例如:MySQL使用identity，Oracle使用sequence.注:如果Hibernate自动选择sequence或者hilo，则所有的表的主键都会从Hibernate默认的sequence或hilo表中取。并且，有的数据库对于默认情况主键生成测试的支持，效率并不是很高。)
        	assigned:指用户手工填入.
        	increment:hibernate会先select max(id)的值加1作为id值.
        	 -->
            <generator class="increment"/>
        </id>
        <!--
	        <property>:为类定义一个持久化的javaBean风格的属性.
	        name="username":标识属性的名字,以小写字母开头;
	        column="username":表主键字段的名字,如果不填写与name一样;
	        update="true"/insert="true":默认为true,表示可以被更新或插入;
         -->
        <property name="username" column="username" type="string" />
        <property name="age" column="age" type="int" />
        <property name="birthday" column="birthday" type="timestamp" />
    </class>

</hibernate-mapping>

package com.alfred.util;

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

public class HibernateUtil {
	private static SessionFactory sf;
	static{
		sf = new Configuration().configure().buildSessionFactory();
	}

	public static Session openSession(){
		return sf.openSession();
	}

	public static void closeSession(Session s){
		s.close();
	}

	public static void closeSessionFactory(){
		sf.close();
	}
}

package com.alfred.main;

import java.sql.Date;
import java.sql.Timestamp;

import org.hibernate.Session;
import org.hibernate.Transaction;

import com.alfred.bean.Employee;
import com.alfred.bean.Person;
import com.alfred.util.HibernateUtil;

public class Main {

	public static void main(String[] args) {
		Person person = new Person("alfred", 22, new Date(System
				.currentTimeMillis()));
		Employee employee = new Employee("Alfred_Emp",3,new Timestamp(System.currentTimeMillis()));

		Session session = HibernateUtil.openSession();
		Transaction tr = session.beginTransaction();
		try {
			session.save(person);
			session.save(employee);
			tr.commit();
		} catch (Exception e) {
			e.printStackTrace();
			tr.rollback();
		} finally {
			HibernateUtil.closeSession(session);
		}
		//关闭sessionfactory，结束程序
		HibernateUtil.closeSessionFactory();
	}

}

<?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>
	    <!-- 数据库的基本连接信息 -->
	    <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
	    <property name="connection.url">jdbc:mysql://127.0.0.1:3306/hibernate_db</property>
	    <property name="connection.username">root</property>
	    <property name="connection.password">123456</property>

	    <!-- sql方言 根据不同的数据库有所区别 -->
	    <property name="dialect">org.hibernate.dialect.MySQL5Dialect</property>

	    <!-- 在标准输出流中输出所有执行的sql -->
	    <property name="show_sql">true</property>
		<!-- 格式化输出的sql
	    <property name="format_sql">true</property>
	     -->

	    <!-- 映射文件 -->
	    <mapping resource="com/alfred/bean/Person.hbm.xml"/>
	    <!-- 使用注释方式 -->
	    <mapping class="com.alfred.bean.Employee" />
	</session-factory>
</hibernate-configuration>