Hibernate:操作配置文件生成数据库[Java编程]

目前很多人利用Hibernate作为长期层,假如我们已经写了配置文件poweracl.hbm.xml,则没必要再吃力写SQL的DDL.除了操纵工具SchemaExport之外,还可以编写程序来自动初始化数据库,并且生成SQL DDL.

(1)Hibernate配置文件hibernate.cfg.xml

<?xml version='1.0' encoding='gb2312'?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-2.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost/hibtest</property>
<property name="hibernate.connection.username">test</property>
<property name="hibernate.connection.password">123456</property>
<property name="hibernate.connection.pool.size">20</property>
<property name="hibernate.show_sql">true</property>
<property name="jdbc.fetch_size">50</property>
<property name="jdbc.batch_size">25</property>
<property name="jdbc.use_scrollable_resultset">false</property>
<property name="hibernate.dialect">net.sf.hibernate.dialect.MySQLDialect</property>
<!-- Mapping files -->
<mapping resource="com/hibtest/poweracl.hbm.xml"/>
</session-factory>
</hibernate-configuration>

注意:（1）JDBC驱动为com.mysql.jdbc.Driver,可以按照所利用的库而改换.

（2）dialect为数据库方言,按照所利用数据库差别而差别.这里是Mysql.

（3）jdbc.fetch_size和jdbc.batch_size太小会降低性能,这里是倡议设置.

（4）mapping文件按照文件所在途径而差别.这里是放在WEB-INF/classes/com/hibtest/目录下.

(2)数据库映射配置poweracl.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="com.hibtest.user" table="user" discriminator-value="W">
<id name="loginname" type="string" >
<column name="loginname" sql-type="char(16)" not-null="true"/>
<generator class="assigned"/>
</id>
<property name="password" type="string">
<column name="password" sql-type="varchar(20)" />
</property>
<property name="name" type="string">
<column name="name" sql-type="varchar(20)" />
</property>
<property name="email" type="string">
<column name="email" sql-type="varchar(60)" />
</property>
<property name="modified" type="date">
<column name="modifier" />
</property>
<property name="creater" type="date">
<column name="creater" />
</property>
<property name="lastlogin" type="date">
<column name="lastlogin" />
</property>
</class>
</hibernate-mapping>

阐明:具体的poweracl.hbm.xml要按照数据库表而设置,这里只是摆列一个user表.

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