JPA Hibernate 项目中需要 DataSource 吗？

发布于 2024-12-16 12:46:16 字数 1450 浏览 5 评论 0原文

我正在准备一些使用 JPA 2.0、Hibernate 作为提供程序、MySQL 5 作为数据库的应用程序，它将部署在 JBoss AS 7.0.2 上。
我已经在 persistence.xml 中配置了一些基础知识，并且进入了某种状态的麻烦。我注意到有些人还在 JBoss 管理控制台级别定义了一些特定的数据源。
我的问题是。我真的需要担心 Hibernate 应用程序中的某些 DataSource 或类似的东西吗？
我认为这在旧的 JDBC 方法中很重要。
在一些显示示例的书籍中，持久性中没有这样的配置。 xml 或 hibernate.cfg.xml
我是否必须将 mysql 连接器放入 JBOSS_HOME/standalone/deployments 目录才能在我的应用程序中使用 MySQL？

以下是我的 persistence.xml 文件的内容：

<?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="SomeApp">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <properties>
            <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver" />
            <property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/somedb" />
            <property name="hibernate.connection.username" value="" />
            <property name="hibernate.connection.password" value="" />
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect" />
        </properties>
    </persistence-unit>
</persistence>

原文

I am preparing some application with usage of JPA 2.0, Hibernate as provider, MySQL 5 as database, which will be deployed on JBoss AS 7.0.2.
I have already configured some basics in persistence.xml and I came into some kind of trouble. I have noticed that some people also defines some specific DataSource on JBoss Management Console level.
My question is. Do I really need to worry about some DataSource or anything like that in Hibernate application?
I thought it is important in old JDBC approach.
In some books, where examples are shown, there is no such configuration in persistence.xml or hibernate.cfg.xml
Do I have to place mysql connector into JBOSS_HOME/standalone/deployments directory to use MySQL in my application?

Here is content of my persistence.xml file:

<?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="SomeApp">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <properties>
            <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver" />
            <property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/somedb" />
            <property name="hibernate.connection.username" value="" />
            <property name="hibernate.connection.password" value="" />
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect" />
        </properties>
    </persistence-unit>
</persistence>

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格子衫的從容 2024-12-23 12:46:16

那么，您可以通过以下方式访问数据库：

提供 url/驱动程序/密码/等。使用 jpa-provider 属性（在您的情况下为 hibernate.connection.*）或 JPA 2.0 标准化 javax.persistence.jdbc 中的 persistence.xml 中的信息。 * 的 - 这基本上看起来像您发布的示例，
在 ApplicationServer 中创建数据源并在 persistence.xml 中引用它（通过它的您在创建过程中提供的 JNDI 名称）可能与此类似（为了简洁起见，没有 XML 模式定义）：
```
<持久化>
    ;
        org.hibernate.ejb.HibernatePersistence
        jdbc/myDB;
    
```

您现在实际执行的操作（使用这些属性）是使用 JDBC。

我肯定会选择在 ApplicationServer 中创建数据源，而不是在 persistence.xml 的属性中提供它。它允许您动态更改最终数据库、其类型、凭据、管理连接池等，甚至无需触及描述符。

它也更安全，因为凭据不会写入服务器上留下的纯文件中。

附带说明一下，请记住，javax.persistence.jdbc.* 属性是 Java SE 环境的 JPA 提供程序必须要求，但对于Java EE来说它是可选。

希望有帮助！

Well, you can either access the database by:

providing the url/driver/password/etc. information in the persistence.xml using your jpa-provider properties (in your case hibernate.connection.*) or the JPA 2.0 standardised javax.persistence.jdbc.* ones - this basically looks like the example you've posted,
creating a Data Source in the ApplicationServer and just referring to it in the persistence.xml (through it's JNDI name you provide during creation) which might look similar to this (without the XML schema definition for the sake of brevity) :
```
<persistence>
    <persistence-unit name="SomeApp">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <jta-data-source>jdbc/myDB</jta-data-source>
    </persistence-unit>
</persistence>
```

What you're actually doing right now (with these properties) is using the JDBC.

I would definitely go with the creation of the Data Source in the ApplicationServer rather than providing it in the properties in persistence.xml. It allows you to dynamically change the end-database, it's type, credentials, manage connection pools, etc. without even touching your descriptor.

It's also safer, as the credentials are not written in the plain file left on your server.

As a side note, please remember that the javax.persistence.jdbc.* properties are a JPA provider must requirement for the Java SE environment, but it's optional for Java EE.

Hope that helps!

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