java持久性。xml vs DispatcherServlet

Question

我使用的是JPA 2.0，Hibernate 3注释版本，问题是我对持久性感到困惑。xml&；调度员服务

我的坚持。xml文件包含：

<?xml version="1.0" encoding="UTF-8"?>

<persistence version="2.0"
    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_2_0.xsd">

    <persistence-unit name="Hello" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
         <class>models.student</class>

        <properties>
            <property name="hibernate.show_sql" value="true" />
            <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
            <property name="javax.persistence.jdbc.url" value="jdbc:mysql://127.0.0.1:3306/test"/>
            <property name="javax.persistence.jdbc.user" value="root" />
            <property name="javax.persistence.jdbc.password" value="admin" />
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLInnoDBDialect"/>
        </properties>

    </persistence-unit>

</persistence>

在dispatcher servlet文件中，我有以下bean：

<bean id="dataSource"
    class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="com.mysql.jdbc.Driver" />
    <property name="url" value="jdbc:mysql://localhost:3306/test" />
    <property name="username" value="root" />
    <property name="password" value="admin" />
</bean>


<bean id="entityManagerFactory"
    class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
    <property name="persistenceUnitName" value="Hello" />
    <property name="dataSource" ref="dataSource" />
    <property name="jpaVendorAdapter">
        <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
            <property name="databasePlatform" value="org.hibernate.dialect.MySQL5InnoDBDialect" />
            <property name="showSql" value="true" />
            <property name="generateDdl" value="true" />
        </bean>
    </property>
</bean>



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

<bean class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" />

问题是：为什么我们需要将所有属性（DriverClassName、URL、用户名、密码）都放在这两个持久性中。DispatcherServlet中的xml和数据源bean

我正在学习，这让我很困惑，请帮助我

Answer 1

实际上这里有双重配置

您需要persistence.xml或bean定义

看看here