Firebase Auth - 使用电子邮件和密码 - 检查用户是否已注册

8 回答

• 3

  要检测具有该电子邮件地址的用户是否已存在，您可以检测 createUserWithEmailAndPassword () 的调用何时因 auth/email-already-in-use 而失败 . 我看到@Srinivasan刚刚发布了一个答案 .

  或者，您可以通过调用fetchSignInMethodsForEmail()（以前称为fetchProvidersForEmail()）来检测已使用的电子邮件地址 .

  回复于 2024-05-06T08:04:36+08:00
• 11

  当用户尝试使用相同的电子邮件地址创建用户时，任务响应将为 "Response: The email address is already in use by another account."

  mFirebaseAuth.createUserWithEmailAndPassword(email,password)
                  .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                      @Override
                      public void onComplete(@NonNull Task<AuthResult> task) {                           
                          if(task.isSuccessful()){
                             //User registered successfully
                          }else{
                              Log.i("Response","Failed to create user:"+task.getException().getMessage());
                          }
                      }
                  });
  

  

  

  回复于 2024-05-06T08:04:36+08:00
• 6

  首先，您需要确保在Firebase控制台中启用了该限制（帐户和电子邮件地址设置） . 看看@ Srinivasan的回答 .

  然后，在您的Java代码中执行此操作：

  firebaseAuthenticator.createUserWithEmailAndPassword(email, password)
                  .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                      @Override
                      public void onComplete(@NonNull Task<AuthResult> task) {
                          if (!task.isSuccessful()) {
  
                              if (task.getException() instanceof FirebaseAuthUserCollisionException) {
                                  Toast.makeText(SignUpActivity.this, "User with this email already exist.", Toast.LENGTH_SHORT).show();
                              }
  
  
                          } else {
                              sendVerificationEmail();
                              startActivity(new Intent(SignUpActivity.this, DetailsCaptureActivity.class));
                          }
  
                          // ...
                      }
                  });
  

  这就是诀窍发生的地方：

  if (task.getException() instanceof FirebaseAuthUserCollisionException) {
                              Toast.makeText(SignUpActivity.this, 
            "User with this email already exist.", Toast.LENGTH_SHORT).show();
  

  使用电子邮件和密码注册用户时可能会抛出几个异常，但我们感兴趣的是 FirebaseAuthUserCollisionException . 顾名思义，如果电子邮件已经存在，则抛出此异常 . 如果抛出的异常是此类的实例，请让用户知道 .

  回复于 2024-05-06T08:04:36+08:00
• 12

  作为@Frank在这里回答的做法是使用 fetchProvidersForEmail() 的代码

  private boolean checkAccountEmailExistInFirebase(String email) {
                  FirebaseAuth mAuth = FirebaseAuth.getInstance();
                  final boolean[] b = new boolean[1];
                  mAuth.fetchProvidersForEmail(email).addOnCompleteListener(new OnCompleteListener<ProviderQueryResult>() {
                      @Override
                      public void onComplete(@NonNull Task<ProviderQueryResult> task) {
                          b[0] = !task.getResult().getProviders().isEmpty();
                      }
                  });
                  return b[0];
              }
  

  回复于 2024-05-06T08:04:36+08:00
• 4

  我正在调查这种情况，我们可以检测用户是否存在，并执行注册和登录 . fetchProvidersForEmail 现在是最好的选择 . 我找到了 this 教程 . 希望它也能帮到你！

  回复于 2024-05-06T08:04:36+08:00
• -2

  private ProgressDialog progressDialog;
  progressDialog.setMessage("Registering, please Wait...");
  progressDialog.show();
  
  mAuth.createUserWithEmailAndPassword(email, password)
              .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                  @Override
                  public void onComplete(@NonNull Task<AuthResult> task) {
  
                      //checking if success
                      if (task.isSuccessful()) {
                          //Registration was successfull:
                          Toast.makeText(RegistrationActivity.this, "Successfully registered!", Toast.LENGTH_LONG).show();
  
                      } else {
                          //Registration failed:
                          //task.getException().getMessage() makes the magic
                          Toast.makeText(RegistrationActivity.this, "Registration failed! " + "\n" + task.getException().getMessage(), Toast.LENGTH_LONG).show();
                      }
                      progressDialog.dismiss();
                  }
              });
  

  回复于 2024-05-06T08:04:36+08:00
• 0

  将以下代码添加到 MainActivity.java 文件 . 当用户尝试使用相同的电子邮件地址注册时，将弹出一条消息"The email address is already used by another account"作为 Toast

  mAuth.createUserWithEmailAndPassword(email,password).addOnCompleteListener(new OnCompleteListener<AuthResult>() {
                  @Override
                  public void onComplete(@NonNull Task<AuthResult> task) {
  
                      if(!task.isSuccessful()){
  
                          Toast.makeText(MainActivity.this, task.getException().getMessage(), Toast.LENGTH_SHORT).show();
  
                      }
                      if(task.isSuccessful()){
                          Toast.makeText(MainActivity.this, "Sign up successfull", Toast.LENGTH_SHORT).show();
                      }
  
                  }
              });
  

  回复于 2024-05-06T08:04:36+08:00
• 0

  You do not have to do anything because the backend of Firebase will do the job.

  除非您指的是重新验证应用程序 . 以一个例子为例，w

  回复于 2024-05-06T08:04:36+08:00