hibernate通过配置文件生成数据库信息

hibernate可以通过配置文件在数据库生成相应的数据库信息。也可以把数据库的信息生成相应的代码(实体类操作类和映射文件)

下面是通过代码默认对hibernate.cfg.xml信息在数据库生成信息。事先要建好空的数据库

<?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>  
        <property name="show_sql">true</property>  
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>  
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>  
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/guesswhat?useUnicode=true&amp;characterEncoding=utf8</property>  
        <property name="hibernate.connection.username">root</property>  
        <property name="hibernate.connection.password">1234</property>  
        <mapping resource="com/us/google/domains/TUser.hbm.xml"/>  
        <mapping resource="com/us/google/domains/TUrl.hbm.xml"/>  
    </session-factory>  
</hibernate-configuration> 

列出一个表的单独配置信息

<?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 package="com.us.google.domains">
    <class name="TUser" table="t_user">
        <id name="id" column="id">
            <generator class="identity"></generator>
        </id>
        <property name="username" column="username"></property>
        <property name="password" column="password"></property>
    </class>
</hibernate-mapping> 

执行操作

package com.us.google.util;

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

public class GenerateSql {

    public static void main(String[] args) {

        //默认读取hibernate.cfg.xml
        Configuration cfg = new Configuration().configure();

        //生成并输出sql到文件(当前目录)和数据库
        SchemaExport export = new SchemaExport(cfg);

        //true 在控制台打印sql语句，true 导入sql语句到数据库，即可执行
        export.create(true, true);
    }
}

运行截图如下，在控制台打印出了执行的sql语句（建立表）

即在数据生成了信息。但是这样比较麻烦，等下说建好表如何生成代码

发现上面的写法过时了 现在是hibernate5 推荐下面的写法

ServiceRegistry serviceRegistry = (ServiceRegistry) new StandardServiceRegistryBuilder()
                .configure().build();
        MetadataImplementor metadataImplementor = (MetadataImplementor) new MetadataSources(
                serviceRegistry).buildMetadata();
        SchemaExport export = new SchemaExport(serviceRegistry,
                metadataImplementor);
        export.create(true, true);