在决定异常是否合适时，需要考虑一些有用的事情:

what level of code you want to have run after the exception candidate occurs - that is, how many layers of the call stack should unwind. You generally want to handle an exception as close as possible to where it occurs. For username/password validation, you would normally handle failures in the same block of code, rather than letting an exception bubble up. So an exception is probably not appropriate. (OTOH, after three failed login attempts, control flow may shift elsewhere, and an exception may be appropriate here.) Is this event something you would want to see in an error log? Not every exception is written to an error log, but it's useful to ask whether this entry in an error log would be useful - i.e., you would try to do something about it, or would be the garbage you ignore.

If it's code running inside a loop that will likely cause an exception over and over again, then throwing exceptions is not a good thing, because they are pretty slow for large N. But there is nothing wrong with throwing custom exceptions if the performance is not an issue. Just make sure that you have a base exception that they all inherite, called BaseException or something like that. BaseException inherits System.Exception, but all of your exceptions inherit BaseException. You can even have a tree of Exception types to group similar types, but this may or may not be overkill.

因此，简短的回答是，如果它不会导致显著的性能损失(除非抛出大量异常，否则不应该如此)，那么就继续执行。

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.

我同意japollock的说法当你不确定手术的结果时就放弃接受。调用api、访问文件系统、数据库调用等。任何时候你都要超越编程语言的“界限”。

我想补充一点，请随意抛出一个标准异常。除非你打算做一些“不同”的事情(忽略，电子邮件，日志，显示twitter鲸鱼图片之类的东西)，否则不要费心自定义异常。

异常与返回错误代码参数应该是关于流控制的，而不是哲学(错误有多“异常”):

void f1() throws ExceptionType1, ExceptionType2 {}

void catchFunction() {
  try{
    while(someCondition){
      try{
        f1(); 
      }catch(ExceptionType2 e2){
        //do something, don't break the loop
      }
    }
  }catch(ExceptionType1 e1){
    //break the loop, do something else
  }

}

抛出异常的经验法则非常简单。当你的代码进入UNRECOVERABLE INVALID状态时，你可以这样做。如果数据被泄露，或者您无法回溯到目前为止发生的处理，那么您必须终止它。你还能做什么呢?您的处理逻辑最终将在其他地方失败。如果你能以某种方式恢复，那么就这样做，不要抛出异常。

在你的特定情况下，如果你被迫做一些愚蠢的事情，比如接受提款，然后才检查用户/密码，你应该通过抛出一个异常来终止这个过程，通知发生了一些不好的事情，并防止进一步的损害。