Detailed description of hibernate automatic table creation configuration, detailed description of hibernate Creation

Detailed description of hibernate automatic table creation configuration, detailed description of hibernate Creation

Detailed description of the configuration of automatic table creation by hibernate

Configure Automatic table creation:

<Prop key = "hibernate. hbm2ddl. auto"> update </prop> // used when creating a project for the first time. After the project is stable, note that there are four values:
Update: automatically updates the table structure based on the model object. When hibernate is started, the database is automatically checked. If a table is missing, the table is automatically created. If a column is missing in the table, the column is automatically added.

There are other parameters:

Create: When hibernate is started, the original table is automatically deleted and all new tables are created. Therefore, the previous data is lost after each start.
Create-drop: When hibernate is started, tables are automatically created. When the program is closed, all corresponding tables are automatically deleted. So at the end of the program, the table and data will no longer exist.

Validate:

Each time hibernate is loaded, the system verifies the creation of the database table structure and only compares it with the database table. A new table is not created, but a new value is inserted.

Then, in the configuration, read the object class ing:

There are three methods:

1. (commonly used) method of scanning packets by annotation:

<property name="packagesToScan"><list><value>com.systop.common.core.dao.testmodel</value></list>

2. Annotations:

<property name="annotatedClasses">  <list><value>com.systop.common.core.dao.testmodel.TestDept</value></list> </property> 

3. mappingResources is used to specify a small number of hibernate configuration files.

Xml Code

<property name="mappingResources">    <list>   <value>WEB-INF/conf/hibernate/cat.hbm.</value>         <value>WEB-INF/conf/hibernate/dog.hbm.xml</value>         ......    </list> </property> 

Instance:

<Bean id = "propertyConfigurer" class = "org. springframework. beans. factory. config. propertyplaceholderpolicer "> <property name =" locations "> <list> <value> classpath *:/dataSource/jdbc. properties </value> </list> </property> </bean> <! -- Configure the data source --> <bean id = "dataSource" class = "org. springframework. jdbc. datasource. driverManagerDataSource "> <property name =" driverClassName "value =" $ {jdbcCcbs. driverClassName} "/> <property name =" url "value =" $ {jdbcCcbs. url} "/> <property name =" username "value =" $ {jdbcCcbs. username} "/> <property name =" password "value =" $ {jdbcCcbs. password} "/> </bean> <! -- Configure SessionFactory --> <bean id = "sessionFactory" class = "org. springframework. orm. hibernate4.LocalSessionFactoryBean"> <! -- <Bean id = "sessionFactory" class = "org. springframework. orm. hibernate3.annotation. annotationSessionFactoryBean "> --> <property name =" dataSource "ref =" dataSource "/> <property name =" hibernateProperties "> <props> <prop key =" hibernate. dialect "> org. hibernate. dialect. mySQLDialect </prop> <! -- Automatically create table configuration --> <! -- <Prop key = "hibernate. hbm2ddl. auto "> update </prop> --> <prop key =" hibernate. show_ SQL "> true </prop> <prop key =" hibernate. format_ SQL "> true </prop> <! -- Result scroll set, related to paging --> <prop key = "jdbc. use_scrollable_resultset"> false </prop> </props> </property> <! -- <Property name = "annotatedClasses"> --> <! -- <List> --> <! -- <Value> com. jason. entity. UserEntity </value> --> <! -- </List> --> <! -- </Property> --> <property name = "packagesToScan"> <list> <value> com. jason. entity </value> </list> </property> </bean>

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