【Hibernate】——SchemaExport自动生成数据库表

           以自动生成User表为例，首先需要配置hibernate.cfg.xml：

<!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="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hibernate_first</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">123456</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>

<mapping resource="com/bjpowernode/hibernate/User.hbm.xml"/>
</session-factory>
</hibernate-configuration>

          hibernate.cfg.xml文件里主要配置数据库连接信息：mysql驱动，数据库表信息，用户名，密码，Hibernate方

言，以及映射文件User.hbm.xml的路径。

         然后是User实体类：

package com.bjpowernode.hibernate;
import java.util.Date;
/**
 * 建立User实体类
 * @author why_768
 *
 */
public class User {
private String id;
private String name;
private String password;
private Date createTime;
private Date expireTime;

public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public Date getCreateTime() {
return createTime;
}
public void setCreateTime(Date createTime) {
this.createTime = createTime;
}
public Date getExpireTime() {
return expireTime;
}
public void setExpireTime(Date expireTime) {
this.expireTime = expireTime;
}


}

          User.hbm.xml映射文件配置：

<?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="com.bjpowernode.hibernate.User" >
<id name="id">
<generator class="uuid"/>
</id>
<property name="name" />
<property name="password"/>
<property name="createTime"/>
<property name="expireTime"/>
</class>
</hibernate-mapping>

            User.hbm.xml文件里的主要配置：id标识（主键标识），name里对应的是User实体里的字段信息，如果想在数

据库表中进行重命名，可以加上column属性；其他的字段信息用property。关于数据库的一对多，一对一以及多对多

的关系也是在这里配置的，稍后会有具体的博客进行说明。

           基本的配置就完成了，然后就可以建立测试类，进行数据库表的导入。

package com.bjpowernode.hibernate;

import org.hibernate.cfg.Configuration;
import org.hibernate.tool.hbm2ddl.SchemaExport;

/**
 * 将hbm生成ddl
 * @author why_768
 *
 */
public class ExportDB {
public static void main(String[] args){
                //hibernate读取hibernate.hbm.xml文件
Configuration cfg=new Configuration().configure();

SchemaExport export=new SchemaExport(cfg);

export.create(true, true);
}
}

           Hibernate默认读取的映射文件是hibernate.properties，在Configuration()后加“.configure()”，就能读取

hibernate.hbm.xml映射文件了。关于SchemaExport，它的源码：

/**
 * Create a schema exporter for the given Configuration
 * and given settings
 */
public SchemaExport(Configuration cfg, Settings settings) throws HibernateException {
dialect = settings.getDialect();
connectionHelper = new SuppliedConnectionProviderConnectionHelper(
settings.getConnectionProvider()
);
dropSQL = cfg.generateDropSchemaScript( dialect );
createSQL = cfg.generateSchemaCreationScript( dialect );
format = settings.isFormatSqlEnabled();
}

           官方解释：Commandline tool to export table schema to the database. This class may also be called from

inside an application. 具体的链接：http://docs.jboss.org/hibernate/orm/4.1/javadocs/org/hibernate/tool/hbm2ddl

/SchemaExport.html

          

            控制台输出结果：

drop table if exists User
create table User (id varchar(255) not null, name varchar(255), password varchar(255), createTime datetime, expireTime datetime, primary key (id))

             当然，数据库中的表也创建好了！