与显式类装入一样，如果类已经装入了，那么只是返回一个引用；否则，装入器会通过委托模型装入类。

As with explicit class loading, if the class is already loaded, then a reference is simply returned; otherwise, the loader goes through the delegation model to load the class.

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如果类已经装入，那么只是返回一个引用；否则，装入器会通过委托模型装入类。

If the class is already loaded, then a reference is simply returned; otherwise, the loader goes through the delegation model to load the class.

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委托对象保持对另一个对象的引用，委托方法在恰当的时间向其发送消息。

The delegating object keeps a reference to the other object, the delegate, and at the appropriate time sends a message to it.

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