Spring Data JPA 的配置文件 已经数据库的状态

<?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:context="http://www.springframework.org/schema/context"
       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/context
                             http://www.springframework.org/schema/context/spring-context.xsd
                             http://www.springframework.org/schema/tx
                       http://www.springframework.org/schema/tx/spring-tx.xsd">

    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
        <property name="driverClass" value="${database1.driverClassName}"/>
        <property name="jdbcUrl" value="${database1.url}"/>
        <property name="user" value="${database1.username}"/>
        <property name="password" value="${database1.password}"/>
        <property name="minPoolSize" value="10"/>
        <property name="maxPoolSize" value="80"/>
        <property name="maxIdleTime" value="1800"/>
        <property name="acquireIncrement" value="2"/>
        <property name="acquireRetryDelay" value="1000"/>
        <property name="maxStatements" value="0"/>
        <property name="initialPoolSize" value="20"/>
        <property name="idleConnectionTestPeriod" value="60"/>
        <property name="acquireRetryAttempts" value="30"/>
        <property name="breakAfterAcquireFailure" value="false"/>
        <property name="testConnectionOnCheckout" value="false"/>
        <property name="testConnectionOnCheckin" value="false"/>
    </bean>

    <bean id="jpaVendorAdapter"
        class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
        <property name="generateDdl" value="false" />
        <!-- <property name="showSql" value="false" /> -->
        <!-- <property name="database" value="MYSQL"/> -->
    </bean>   

    <!-- Class 'org.hibernate.ejb.HibernatePersistence' is marked deprecated -->
    <bean id="persistenceProvider" class="org.hibernate.jpa.HibernatePersistenceProvider"/>

    <bean id="jpaDialect" class="org.springframework.orm.jpa.vendor.HibernateJpaDialect" />

    <bean id="entityManagerFactory"
        class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="persistenceXmlLocation" value="classpath:persistence.xml"/>
        <property name="persistenceUnitName" value="persistenceUnit" />
        <property name="persistenceProvider" ref="persistenceProvider"/>
        <property name="jpaVendorAdapter" ref="jpaVendorAdapter" />
        <property name="jpaDialect" ref="jpaDialect"/>
        <property name="packagesToScan">
            <list>
                <value>com.buwei.webpageapp.domain</value>
            </list>
        </property>
        <property name="jpaProperties">
            <props>
                <prop key="hibernate.show_sql">true</prop>
                <prop key="hibernate.format_sql">false</prop>
                <prop key="hibernate.hbm2ddl.auto">update</prop>
                <prop key="hibernate.connection.charSet">UTF-8</prop>
                <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
            </props>
        </property>
    </bean>       

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

    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"/>
    </bean>

    <tx:annotation-driven transaction-manager="transactionManager" mode="aspectj"/>

</beans>

数据库的更新几种状态：

validate               加载hibernate时，验证创建数据库表结构
create                  每次加载hibernate，重新创建数据库表结构，这就是导致数据库表数据丢失的原因。
create-drop        加载hibernate时创建，退出是删除表结构
update                 加载hibernate自动更新数据库结构

第二种配置：

<?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:jdbc="http://www.springframework.org/schema/jdbc"
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:jpa="http://www.springframework.org/schema/data/jpa"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <!--指定仓库包 -->
    <jpa:repositories base-package="com.smallcode.pan.repository" />

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

    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource" />
    </bean>

    <bean id="entityManagerFactory"
        class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="packagesToScan" value="com.smallcode.pan.model" />
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <property name="database" value="MYSQL" />
                <property name="generateDdl" value="true" />
            </bean>
        </property>
        <property name="jpaProperties">
            <props>
                <prop key="hibernate.show_sql">true</prop>
                <prop key="hibernate.format_sql">false</prop>
                <prop key="hibernate.hbm2ddl.auto">update</prop>
                <prop key="hibernate.connection.charSet">UTF-8</prop>
                <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
            </props>
        </property>
    </bean>

    <bean name="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
        <property name="driverClassName">
            <value>org.gjt.mm.mysql.Driver</value>
        </property>
        <property name="url">
            <value>jdbc:mysql://localhost:3306/scpan</value>
        </property>
        <property name="username">
            <value>root</value>
        </property>
        <property name="password" value="root" />
    </bean>

    <!--扫描业务层 -->
    <context:component-scan base-package="com.smallcode.pan.service" />
</beans>

如果配置了 packagesToScan，就不能配置persistenceUnitName，否则packagesToScan会完全不起作用，