这里所示的代码是一些用来查询和创建消息的标准 JPA 代码。
The code here is just standard JPA code for querying and creating messages.
如清单12所示，这里可以使用简写形式，因为Retention只有一个成员变量。
As you can tell from Listing 12, you can use the shorthand form here, because Retention has a single-member variable.
其中一个有趣的应用程序就是virsh(这里所示)，它是一种虚拟shell。
One of the interesting applications is virsh (demonstrated here), which is a virtualization shell.
应用推荐