对于每个请求和响应，此类将直接打印操作及其发出者或接收者。

For each Request and Response, this class will simply print out the action and who it is to or from.

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阻止访问者查看并打印您的源代码。

Prevent visitors from viewing and printing your source code.

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订阅者接收消息，并准确地打印出该消息，如控制台窗口中所示。

The subscriber receives the message and prints it out exactly as shown in the console window.

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