通常，这对于在应用服务器上运行的应用程序是不可能的，因为这些应用程序使用连接池，连接不是个人化的。

Generally, it is not possible for applications running on an application server because these applications use connection pooling so that connections are not personalized.

youdao

比如数据库连接池就是单例设计模式的一个例子：我们一般不想让应用程序具有连接池类的多个资源密集型实例。

An example use case for a singleton would be a database connection pool: you don't want your application to have multiple resource-intensive instances of a connection pool class.

youdao

现在，应用程序可以获得连接池。

Now the connection pool is available to the application.

youdao