其他人建议不应该使用异常，因为在正常流程中，如果用户输入错误，就会出现错误的登录。我不同意，我不明白其中的道理。与打开文件相比。如果该文件不存在或由于某种原因不可用，则框架将抛出异常。使用上述逻辑是微软的一个错误。他们应该返回一个错误代码。解析、webrequest等也一样。

I don't consider a bad login part of a normal flow, it's exceptional. Normally the user types the correct password, and the file does exist. The exceptional cases are exceptional and it's perfectly fine to use exceptions for those. Complicating your code by propagating return values through n levels up the stack is a waste of energy and will result in messy code. Do the simplest thing that could possibly work. Don't prematurely optimize by using error codes, exceptional stuff by definition rarely happens, and exceptions don't cost anything unless you throw them.

异常用于异常行为、错误、失败等事件。功能行为、用户错误等应该由程序逻辑来处理。由于错误的帐户或密码是登录例程中逻辑流的一部分，因此它应该能够毫无例外地处理这些情况。

我想说的是，如果发生了意想不到的行为，应该抛出异常。

比如试图更新或删除一个不存在的实体。它应该在异常可以处理并且有意义的地方被捕获。如果要以另一种方式继续工作，请在Api级别上添加日志记录或返回特定的结果。

如果您期望某些事情是这样的，那么您应该构建代码来检查并确保它是正确的。

异常是一种代价高昂的效果，例如，如果您有一个用户提供了无效的密码，那么通常更好的方法是返回一个失败标志，或其他一些无效的指示。

这是由于异常处理的方式，真正的错误输入和唯一的关键停止项应该是异常，而不是失败的登录信息。

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
  }

}

我有三种情况。

Bad or missing input should not be an exception. Use both client side js and server side regex to detect, set attributes and forward back to the same page with messages. The AppException. This is usually an exception that you detect and throw with in your code. In other words these are ones you expect (the file does not exist). Log it, set the message, and forward back to the general error page. This page usually has a bit of info about what happened. The unexpected Exception. These are the ones you don't know about. Log it with details and forward them to a general error page.

希望这能有所帮助