android - Firebase Android 查询和 Java 方法

Question

我正在尝试验证用户名是否已存在于 Firebase 数据库中，并创建了一个方法来验证它。

如果用户名可用，该方法应返回 true，如果用户名已被占用，则返回 false。

public boolean isUsernameValid(final String newUsername, String oldUsername){
    if(newUsername.equals(oldUsername)){
        //if username is not changed
        return true;
    }else {
        userValid = true;
        databaseReference.orderByChild("Username").equalTo(newUsername).addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                long userCount = dataSnapshot.getChildrenCount();
                if(userCount!=0){
                    userValid = false;
                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }

        });
        return userValid;   //username is valid if this returns true
    }
}

此方法首先返回 UserValid bool 值，然后查询数据库。如果我遗漏了什么，请告诉我。

这首先返回 true，然后在数据库中搜索用户名，因此，它总是覆盖数据库中的用户名。

这个方法是从这里调用的:

    if(!TextUtils.isEmpty(str_firstName)
                && !TextUtils.isEmpty(str_lastName)
                && !TextUtils.isEmpty(str_username)
                && verify.isEmailValid(str_email)
                && verify.isMobileNoValid(str_mobile)

//here
                && verify.isUserNameValid(str_username, globalSharedPrefs.getUserDetail("username").toString())){
            progressDialog.setMessage("Saving Profile ...");
            progressDialog.show();

            //saving the photo
            if(isImageClicked) {
                filepath = storageReference.child("profile_photos").child(globalSharedPrefs.getUserDetail("uid").toString());
                filepath.putFile(imageUri).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
                    @Override
                    public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
                        //TODO: add picture remote/edit button in the XML
                        isImageClicked = false;
                        downloadUri = taskSnapshot.getDownloadUrl();
                        databaseReference.child("Profile Picture").setValue(downloadUri.toString());
                        uploadUserInfo();
                        Toast.makeText(UserProfileActivity.this, "Profile Saved.!", Toast.LENGTH_LONG)
                                .show();
                    }
                }).addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {
                        progressDialog.dismiss();
                        updateProfileUI();
                        clickEditProfileButton(false);
                        Toast.makeText(UserProfileActivity.this, "Update Failed.!", Toast.LENGTH_LONG)
                                .show();
                    }
                });
            }

数据库结构

   {
  "userinfo" : {
    "J6Y4Dtxe7Nh45B653U5AVXHFrSJ2" : {
      "AccountId" : "",
      "DOB" : "21 Jun, 2017",
      "First Name" : "Krishna",
      "Last Name" : "kk",
      "Mobile" : "",
      "Username" : "kittuov",
      "uid" : "J6Y4Dtxe7Nh45B653U5AVXHFrSJ2"
    },
    "ck8x94FeHtUbC9DgHCkxmQt93Ar1" : {
      "AccountId" : "",
      "DOB" : "7 Dec, 1992",
      "First Name" : "Seshagiri Rao",
      "Last Name" : "Kornepati",
      "Mobile" : "",
      "Username" : "seshu1",
      "uid" : "ck8x94FeHtUbC9DgHCkxmQt93Ar1"
    },
    "iDBn0lYIZFSgll9KyVje0T6JFIy2" : {
      "AccountId" : "",
      "DOB" : "",
      "First Name" : "Ramesh",
      "Last Name" : "Devarapu",
      "Mobile" : "",
      "Username" : "rameshb",
      "uid" : "iDBn0lYIZFSgll9KyVje0T6JFIy2"
    }
  }

Answer 1

试试这个

if(str_username.equals(globalSharedPrefs.getUserDetail("username").toString()))){
    sumbit();
}else {

    databaseReference.orderByChild("Username").equalTo(newUsername).addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            long userCount = dataSnapshot.getChildrenCount();
            if(userCount==0){
                sumbit();
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }

    });

    private void sumbit(){
if(!TextUtils.isEmpty(str_firstName)
           && !TextUtils.isEmpty(str_lastName)
           && !TextUtils.isEmpty(str_username)
           && verify.isEmailValid(str_email)
           && verify.isMobileNoValid(str_mobile)
        ){
       progressDialog.setMessage("Saving Profile ...");
       progressDialog.show();

       //saving the photo
       if(isImageClicked) {
           filepath = storageReference.child("profile_photos").child(globalSharedPrefs.getUserDetail("uid").toString());
           filepath.putFile(imageUri).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
               @Override
               public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
                   //TODO: add picture remote/edit button in the XML
                   isImageClicked = false;
                   downloadUri = taskSnapshot.getDownloadUrl();
                   databaseReference.child("Profile Picture").setValue(downloadUri.toString());
                   uploadUserInfo();
                   Toast.makeText(UserProfileActivity.this, "Profile Saved.!", Toast.LENGTH_LONG)
                           .show();
               }
           }).addOnFailureListener(new OnFailureListener() {
               @Override
               public void onFailure(@NonNull Exception e) {
                   progressDialog.dismiss();
                   updateProfileUI();
                   clickEditProfileButton(false);
                   Toast.makeText(UserProfileActivity.this, "Update Failed.!", Toast.LENGTH_LONG)
                           .show();
               }
           });
       }
       }