【Hibernate】——SchemaExport自動生成數據庫表

           以自動生成User表爲例，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文件裏主要配置數據庫連接信息：mysql驅動，數據庫表信息，用戶名，密碼，Hibernate方

言，以及映射文件User.hbm.xml的路徑。

         然後是User實體類：

package com.bjpowernode.hibernate;
import java.util.Date;
/**
 * 建立User實體類
 * @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文件裏的主要配置：id標識（主鍵標識），name裏對應的是User實體裏的字段信息，如果想在數

據庫表中進行重命名，可以加上column屬性；其他的字段信息用property。關於數據庫的一對多，一對一以及多對多

的關係也是在這裏配置的，稍後會有具體的博客進行說明。

           基本的配置就完成了，然後就可以建立測試類，進行數據庫表的導入。

package com.bjpowernode.hibernate;

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

/**
 * 將hbm生成ddl
 * @author why_768
 *
 */
public class ExportDB {
	public static void main(String[] args){
                //hibernate讀取hibernate.hbm.xml文件
		Configuration cfg=new Configuration().configure();
		
		SchemaExport export=new SchemaExport(cfg);
		
		export.create(true, true);
	}
}

          Hibernate默認讀取的映射文件是hibernate.properties，在Configuration()後加“.configure()”，就能讀取

hibernate.hbm.xml映射文件了。關於SchemaExport，它的源碼：

	/**
	 * 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();
	}

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

inside an application. 具體的鏈接：http://docs.jboss.org/hibernate/orm/4.1/javadocs/org/hibernate/tool/hbm2ddl

/SchemaExport.html

          

            控制檯輸出結果：

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))

            當然，數據庫中的表也創建好了！