将tomcat的连接池与JPA一起使用 [英] Using tomcat's connection pool with JPA

问题描述

我想在运行于tomcat的Web应用程序中将连接池与JPA/TopLink一起使用.以前，我使用jdbc的Connection和Statement类来处理数据库中的数据.以这种方式使用连接池，我只需在context.xml中声明资源并在应用程序中获取此资源:

I want to use connection pool with JPA/TopLink in my web app running on tomcat.Earlier I use jdbc's Connection and Statement classes to manipulate data in database; to use connection pool in that way I simply declare resource in context.xml and get this resource in application:

Context c = new InitialContext();
DataSource source = (DataSource) ((Context)c.lookup("java:comp/env")).lookup("jdbc/MySource");

现在我想在JPA中使用这样的连接池.我该怎么办?

And now I want to use such connection pool with JPA. How can i do this?

另一个问题:在某些示例中，我看到reosurce在context.xml中声明，然后在<中的web.xml中声明.资源参考>.为什么我应该在不同的地方声明它还是相同的声明，我的意思是它等同于context.xml中的声明?

One more question: I've seen in some examples that the reosurce is declared in context.xml and then it is declared in web.xml in < resource-ref>. Why I should declare it in different places or is it the same declaration, I mean is it an equivalent of declaration in context.xml?

推荐答案

现在我想在JPA中使用这样的连接池.我该怎么办?

假定您已经在context.xml中声明了<Resource>创建的连接池数据源，那么您只需在Webapp的/META-INF/persistence.xml中声明JPA的数据源使用情况.

Assuming that you've already declared the connection pooled datasource creation by <Resource> in a context.xml, then you just need to declare the datasource usage for JPA in the webapp's /META-INF/persistence.xml.

<persistence-unit name="YourPersistenceUnit" transaction-type="JTA">
    <jta-data-source>jdbc/MySource</jta-data-source>
</persistence-unit>

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另一个问题:在某些示例中，我看到reosurce在context.xml中声明，然后在web.xml中在<resource-ref>中声明.为什么我应该在不同的地方声明它还是相同的声明，我的意思是它等同于context.xml中的声明?

One more question: I've seen in some examples that the reosurce is declared in context.xml and then it is declared in web.xml in <resource-ref>. Why I should declare it in different places or is it the same declaration, I mean is it an equivalent of declaration in context.xml?

context.xml中的<Resource>中的一个定义了servlet容器对数据源的创建.它可以被多个Web应用程序使用. web.xml中的<resource-ref>一词定义了特定Web应用程序对数据源的使用情况.注意:使用JPA时，不需要web.xml中的一个.它进入persistence.xml.

The <Resource> one in context.xml definies the creation of the datasource by the servletcontainer. It can be used by multiple webapps. The <resource-ref> one in web.xml definies the usage of the datasource by the particular webapp. Note: when using JPA, you don't need the one in web.xml. It goes into persistence.xml.

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