问题

我想要在我的登录页面上，通过电子邮件/密码登录用户，当"角色"等于"洪水受害者"时（另一个角色是"救援者"和"管理员"）。洪水受害者页面是"HomeActivity.class"，而救援者页面是"HomeRes.class"。

以下是我的LoginActivity代码：

LoginActivity：

mAuth.signInWithEmailAndPassword(userEmail, userPswd)
    .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
        @Override
        public void onComplete(@NonNull Task<AuthResult> task) {
            if (task.isSuccessful()) {
                //登录成功，更新UI显示已登录用户的信息
                Toast.makeText(LoginActivity.this, "登录成功！", Toast.LENGTH_SHORT).show();

                FirebaseDatabase firebaseDatabase = FirebaseDatabase.getInstance();
                DatabaseReference reference = firebaseDatabase.getReference().child("User");

                //检查用户是否已成功注册

                reference.orderByChild("userName").equalTo(userEmail).addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(@NonNull DataSnapshot snapshot) {
                        if (snapshot.exists()) {
                            Log.d("用户存在", "欢迎!");
                            String value = snapshot.child("userRole").getValue().toString();

                            if (value.equals("Flood Victim") && value != null) {
                                startActivity(new Intent(LoginActivity.this, HomeActivity.class));
                                finish();
                            } else if (value.equals("Rescuer")) {
                                startActivity(new Intent(LoginActivity.this, HomeRescuer.class));
                                finish();
                            } else {
                                startActivity(new Intent(LoginActivity.this, HomeFv.class));
                                finish();
                            }
                        }
                    }

                    @Override
                    public void onCancelled(@NonNull DatabaseError error) {}
                });

            } else {
                //如果登录失败，向用户显示错误消息
                Toast.makeText(LoginActivity.this, "错误" + task.getException().getMessage(), Toast.LENGTH_SHORT).show();
            }
        }
    });
}

  mAuth.signInWithEmailAndPassword(userEmail, userPswd)
.addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
@Override
public void onComplete(@NonNull Task<AuthResult> task) {
if (task.isSuccessful()) {
//Sign in success, update UI with the signed-in user's information
Toast.makeText(LoginActivity.this, "Login Successfull!",Toast.LENGTH_SHORT).show();
FirebaseDatabase firebaseDatabase = FirebaseDatabase.getInstance();
DatabaseReference reference = firebaseDatabase.getReference().child("User");
//check if user has success registered
reference.orderByChild("userName").equalTo(userEmail).addListenerForSingleValueEvent(new ValueEventListener()  {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
if (snapshot.exists()) {
Log.d("User exists", "Welcome!");
String value =  snapshot.child("userRole").getValue().toString();
if (value.equals("Flood Victim") && value != null) {
startActivity(new Intent(LoginActivity.this, HomeActivity.class));
finish();
} else if (value.equals("Rescuer")) {
startActivity(new Intent(LoginActivity.this, homeRescuer.class));
finish();
} else {
startActivity(new Intent(LoginActivity.this, homeFv.class));
finish();
}
}
}
@Override
public void onCancelled(@NonNull DatabaseError error) {}
});
}else {
// If sign in fails, display a message to the user.
Toast.makeText(LoginActivity.this, "Error" + task.getException().getMessage(), Toast.LENGTH_SHORT).show();
}
}
});
}
}
}

答案1

得分: 0

当您执行针对Firebase数据库的查询时，可能会有多个结果。因此，快照包含这些结果的列表。即使只有一个结果，快照也将包含一个结果的列表。

您的 onDataChange 需要通过循环遍历快照的子项来处理这个列表。

reference.orderByChild("userName").equalTo(userEmail).addListenerForSingleValueEvent(new ValueEventListener() {
  @Override
  public void onDataChange(@NonNull DataSnapshot snapshot) {
    for (DataSnapshot userSnapshot: snapshot.getChildren()) { // 循环遍历快照的子项
       String value = userSnapshot.child("userRole").getValue(String.class); // 获取 "userRole" 的值

        if ("Flood Victim".equals(value)) { // 如果值等于 "Flood Victim"
          startActivity(new Intent(LoginActivity.this, HomeActivity.class));
          finish();
       } else if ("Rescuer".equals(value)) { // 如果值等于 "Rescuer"
         startActivity(new Intent(LoginActivity.this, homeRescuer.class));
         finish();
       } else {
         startActivity(new Intent(LoginActivity.this, homeFv.class));
         finish();
       }
    }
  }

  @Override
  public void onCancelled(@NonNull DatabaseError error) {
    throw error.toException(); // 永远不要忽略错误
  }
});

reference.orderByChild("userName").equalTo(userEmail).addListenerForSingleValueEvent(new ValueEventListener()  {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
for (DataSnapshot userSnapshot: snapshot.getChildren()) { // 👈
String value = userSnapshot.child("userRole").getValue(String.class); // 👈 
if ("Flood Victim".equals(value)) { // 👈
startActivity(new Intent(LoginActivity.this, HomeActivity.class));
finish();
} else if ("Rescuer".equals(value)) { // 👈 
startActivity(new Intent(LoginActivity.this, homeRescuer.class));
finish();
} else {
startActivity(new Intent(LoginActivity.this, homeFv.class));
finish();
}
}
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
throw error.toException(); // 👈 never ignore errors
}
});