最终，决定取决于是使用异常处理更有助于处理此类应用程序级错误，还是通过您自己的机制(如返回状态代码)更有帮助。我不认为哪个更好有一个严格的规则，但我会考虑:

Who's calling your code? Is this a public API of some sort or an internal library? What language are you using? If it's Java, for example, then throwing a (checked) exception puts an explicit burden on your caller to handle this error condition in some way, as opposed to a return status which could be ignored. That could be good or bad. How are other error conditions in the same application handled? Callers won't want to deal with a module that handles errors in an idiosyncratic way unlike anything else in the system. How many things can go wrong with the routine in question, and how would they be handled differently? Consider the difference between a series of catch blocks that handle different errors and a switch on an error code. Do you have structured information about the error you need to return? Throwing an exception gives you a better place to put this information than just returning a status.

异常类就像“正常”类。当一个新类“是”一个不同类型的对象，具有不同的字段和不同的操作时，您可以创建一个新类。

As a rule of thumb, you should try balance between the number of exceptions and the granularity of the exceptions. If your method throws more than 4-5 different exceptions, you can probably merge some of them into more "general" exceptions, (e.g. in your case "AuthenticationFailedException"), and using the exception message to detail what went wrong. Unless your code handles each of them differently, you needn't creates many exception classes. And if it does, may you should just return an enum with the error that occured. It's a bit cleaner this way.

我对异常的使用有哲学问题。基本上，您期待一个特定的场景发生，但不是明确地处理它，而是将问题推到“其他地方”处理。至于“其他地方”在哪里，谁也说不准。

避免抛出异常的主要原因是抛出异常涉及大量开销。

下面这篇文章指出的一件事是，例外是针对异常条件和错误的。

错误的用户名不一定是程序错误，而是用户错误……

下面是关于。net中的异常的一个不错的起点: http://msdn.microsoft.com/en-us/library/ms229030 (VS.80) . aspx

我个人的指导方针是:当发现当前代码块的基本假设为假时抛出异常。

例1:假设我有一个函数，它应该检查任意类，如果该类继承自List<>，则返回true。这个函数问一个问题:“这个对象是List的后代吗?”这个函数永远不会抛出异常，因为它的操作中没有灰色地带——每个单独的类要么继承了List<>，要么继承了List<>，所以答案总是“是”或“否”。

Example 2: say I have another function which examines a List<> and returns true if its length is more than 50, and false if the length is less. This function asks the question, "Does this list have more than 50 items?" But this question makes an assumption - it assumes that the object it is given is a list. If I hand it a NULL, then that assumption is false. In that case, if the function returns either true or false, then it is breaking its own rules. The function cannot return anything and claim that it answered the question correctly. So it doesn't return - it throws an exception.

这与“负载问题”逻辑谬误相当。每个函数都问一个问题。如果给出的输入使该问题成为谬误，则抛出异常。对于返回void的函数，这条线很难画出来，但底线是:如果函数对其输入的假设违反了，它应该抛出异常，而不是正常返回。

这个等式的另一方面是:如果你发现你的函数经常抛出异常，那么你可能需要改进它们的假设。

安全性与您的示例混为一谈:您不应该告诉攻击者用户名存在，但密码是错误的。这是你不需要分享的额外信息。只要说“用户名或密码不正确”。