Question

我正在使用Spring + JPA + Hibernate开发一个网站。在持久性配置（JPA + Hibernate）中，我将HibernateJpaVendorAdapter的generateDdl属性设置为true，实际上新实体正确地在数据库中创建新表。

一旦创建了表，如果我向实体添加一个属性，我期望HibernateJpaVendorAdapter改变表并添加列。这种情况并没有发生，这很奇怪，因为在Java AbstractJpaVendorAdapter的setGenerateDdl方法文档中有：“设置是否在初始化EntityManagerFactory后生成DDL，创建/ 更新所有相关表。”

JPA + Hibernate配置：

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="${db.driverClassName}" />
    <property name="url" value="${db.url}" />
    <property name="username" value="${db.username}" />
    <property name="password" value="${db.password}" />
</bean>

<bean id="jpaAdapter" class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
    <property name="databasePlatform" value="org.hibernate.dialect.MySQL5Dialect" />
    <property name="showSql" value="${db.showSql}" />
    <property name="generateDdl" value="${db.generateDdl}" />
</bean>

<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
    <property name="jpaVendorAdapter" ref="jpaAdapter" />
    <property name="jpaProperties">
        <props>
            <prop key="hibernate.show_sql">true</prop>
            <prop key="hibernate.format_sql">true</prop>
        </props>
    </property>
    <property name="dataSource" ref="dataSource" />
</bean>

的persistence.xml：

<?xml version="1.0" encoding="UTF-8"?>
<persistence
        xmlns="http://java.sun.com/xml/ns/persistence"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
   http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
        version="1.0">

    <persistence-unit name="m8tsPU" />
</persistence>

我做错了吗？

Answer 1

通过直接设置适当的特定于Hibernate的属性，您可以对DDL生成进行更精细的控制：

<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
     ...
    <property name="jpaProperties">
        <props>
            <prop key="hibernate.hbm2ddl.auto">update</prop>
            ...
        </props>
    </property>
</bean>

或者，您可以使用create-drop代替update，因为在某些情况下update可能会导致问题。但请注意，自动DDL更新不适用于生产用途。

Answer 2

或者，您也可以使用jpaPropertyMap表达相同的属性：

<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> 
     ...
        <property name="jpaPropertyMap">
            <map>
                <entry key="hibernate.hbm2ddl.auto" value="update"/>
                ...
            </map>
        </property>
</bean>

Answer 3

也许到了晚了，但今天我在为遗留应用程序编写测试时遇到了同样的问题。

问题不仅发生在使用generateDdl属性时，而且还会使用HSQL。

要解决此问题，我将数据库从HSQL更改为H2，将数据源从org.springframework.jdbc.datasource.DriverManagerDataSource更改为org.apache.commons.dbcp.BasicDataSource。

spring-context.xml如下所示：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:tx="http://www.springframework.org/schema/tx"
   xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd">

    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="driverClassName" value="org.h2.Driver"/>
        <property name="url" value="jdbc:h2:mem:test"/>
        <property name="username" value="sa"/>
        <property name="password" value=""/>
    </bean>

    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"/>
        </property>
        <property name="dataSource" ref="dataSource"/>
    </bean>

    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="dataSource" ref="dataSource"/>
        <property name="entityManagerFactory" ref="entityManagerFactory"/>
    </bean>

    <tx:annotation-driven/>
...
</beans>

persistence.xml如下所示：

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
      http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
             version="1.0">

    <persistence-unit name="TestPU" transaction-type="RESOURCE_LOCAL">
        <properties>
            <property name="hibernate.show_sql" value="true"/>
            <property name="hibernate.format_sql" value="true"/>
            <property name="hibernate.hbm2ddl.auto" value="create-drop"/>
            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
        </properties>
    </persistence-unit>

</persistence>

我希望它有所帮助。

HibernateJpaVendorAdapter的generateDdl不会改变表

3 个答案: