Hibernate学习2 -- 第一个Hibernate程序

1. 第一个Hibernate项目

1.1. 前期工作

我们首先需要建立一个Java项目，加入如下jar：
* HIBERNATE_HOME/hibernate3.jar
* HIBERNATE_HOME/lib/*.jar
* 数据库驱动
复制hibernate.cfg.xml和log4j.properties到项目的src目录下，这两个文件位于
* HIBERNATE_HOME/etc/

1.2. 建立JavaBean对象(实体类)

Javabean对象是用来映射数据库的一条记录。例如：

package po; //对应数据库T_CUSTOMER中的一条记录,用JavaBean规范编写 public class Customer { private String account; private String password; private String cname; private double cbalance; public Customer(){} public Customer(String account,String password,String cname,double cbalance){ this.account = account; this.password = password; this.cname = cname; this.cbalance = cbalance; } public String getAccount() { return account; } public void setAccount(String account) { this.account = account; } public double getCbalance() { return cbalance; } public void setCbalance(double cbalance) { this.cbalance = cbalance; } public String getCname() { return cname; } public void setCname(String cname) { this.cname = cname; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } }

1.3. 建立类与表的映射文件（.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> <class name="po.Customer" table="T_CUSTOMER"> <!-- 类和表对应 --> <id name="account" column="ACCOUNT"> <!-- 主键 --> <!-- 主键生成策略,assigned表示由用户赋值 --> <generator class="assigned"/> </id> <property name="password" column="PASSWORD"/> <property name="cname" column="CNAME"/> <property name="cbalance" column="CBALANCE"/> </class> </hibernate-mapping>

1.4. 创建hibernate配置文件(hibernate.cfg.xml)

hibernate.cfg.xml是hibernate的配置信息，为了方便跟踪sql执行，在hibernate.cfg.xml文件中加入<property name="hibernate.show_sql">true</property>，例如：

<?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.username">scott</property> <property name="connection.url">jdbc:odbc:School</property> <property name="dialect"> org.hibernate.dialect.Oracle9Dialect </property> <property name="connection.password">tiger</property> <property name="connection.driver_class"> sun.jdbc.odbc.JdbcOdbcDriver </property> <property name="show_sql">true</property> <mapping resource="po/Customer.hbm.xml" /> </session-factory> </hibernate-configuration>

1.5. 编写hbm2ddl工具类

编写hbm2ddl工具类，将实体类生成数据库表，代码如下：

public class ExportDB { public static void main(String[] args) { //读取hibernate.cfg.xml文件 Configuration cfg = new Configuration().configure(); SchemaExport export = new SchemaExport(cfg); export.create(true, true); } }

1.6. CRUD操作

1.6.1.添加

//第一步，读取Hibernate配置文件 Configuration conf = new Configuration().configure(); //第二步,Hibernate操作要使用Session来完成，Session由SessionFactory管理， //生成SessionFactory SessionFactory sf = conf.buildSessionFactory(); //第三步:打开Session,Session的事务不是自动提交的 Session session = sf.openSession(); Customer cus = new Customer("222","222","张三",4000); Transaction tran = session.beginTransaction(); session.save(cus); tran.commit();

1.6.2.删除

Configuration conf = new Configuration().configure(); SessionFactory sf = conf.buildSessionFactory(); Session session = sf.openSession(); Customer cus = new Customer(); session.load(cus, "111"); Transaction tran = session.beginTransaction(); session.delete(cus); tran.commit();

1.6.3.更新

Configuration conf = new Configuration().configure(); SessionFactory sf = conf.buildSessionFactory(); Session session = sf.openSession(); Customer cus = new Customer(); session.load(cus, "111"); cus.setCbalance(cus.getCbalance() + 1000); Transaction tran = session.beginTransaction(); session.update(cus); tran.commit();

1.6.4.查询

Configuration conf = new Configuration().configure(); SessionFactory sf = conf.buildSessionFactory(); Session session = sf.openSession(); Customer cus = new Customer(); session.load(cus, "111"); System.out.println(cus.getAccount()); System.out.println(cus.getPassword()); System.out.println(cus.getCname()); System.out.println(cus.getCbalance());