Question

我正在使用Dart创建用于Firebase电话身份验证的功能。有两个函数getCredential和signIn。当使用try / catch块时，我不确定应该如何编码。非异步函数getCredential应该在try / catch块之外还是内部？

应将其编码为：

  // Sign in with phone
  Future signInWithPhoneNumber(String verificationId, String smsCode) async {
    AuthCredential credential = PhoneAuthProvider.getCredential(
      verificationId: verificationId,
      smsCode: smsCode,
    );
    try {
      AuthResult result = await _auth.signInWithCredential(credential);
      FirebaseUser user = result.user;
      return user;
    } catch (e) {
      print(e.toString());
      return null;
    }
  }

还是应该这样编码？

  // Sign in with phone
  Future signInWithPhoneNumber(String verificationId, String smsCode) async {
    try {
      AuthCredential credential = PhoneAuthProvider.getCredential(
        verificationId: verificationId,
        smsCode: smsCode,
      );
      AuthResult result = await _auth.signInWithCredential(credential);
      FirebaseUser user = result.user;
      return user;
    } catch (e) {
      print(e.toString());
      return null;
    }
  }

如果编码为第二个选项，则try / catch仅适用于异步功能或两者都适用。例如，如果getCredential函数生成错误，是否会在catch块中捕获它？

Answer 1

是的，该catch可以处理在try块中引发的所有事件，这不是异步特定的。为了确认这一点，您可以编写一个在尝试开始时被调用的函数，例如：

// this is a function that throws
void doSomething(String param) {
   if (param == null) {
     throw FormatException('param can not be null'); 
   }
}


Future signInWithPhoneNumber(String verificationId, String smsCode) async {
  try {
    doSomething(null); // this will be caught
    AuthCredential credential = PhoneAuthProvider.getCredential(
      verificationId: verificationId,
      smsCode: smsCode,
    );
    AuthResult result = await _auth.signInWithCredential(credential);
    FirebaseUser user = result.user;
    return user;
  } catch (e) {
    print(e.toString()); // this prints 'FormatException: param can not be null'
    return null;
  }
}

所以异步与是否捕获函数无关，因此最好使用第二个选项。

具有非异步功能的Dart未来

1 个答案: