如何从Firebase云存储检索数据到片段类，例如ProfileFragment.class，它也使用MVVM？

Question

我是新手。尝试了其他资源，但其中大多数都讨论了回收站视图，但是对于我的应用程序，我正在使用视图模型。期待获得帮助。我想从Firebase云存储中检索用户个人资料数据。以下是我到目前为止提到的代码。

ProfileViewModel.java

import androidx.lifecycle.LiveData;
import androidx.lifecycle.MutableLiveData;
import androidx.lifecycle.ViewModel;

public class ProfileViewModel extends ViewModel {

private MutableLiveData<String> mText;

public ProfileViewModel() {
    mText = new MutableLiveData<>();

    mText.setValue( "Your Profile" );
}

public LiveData<String> getText() {
    return mText;
}

}

ProfileFragment.java

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.Observer;
import androidx.lifecycle.ViewModelProviders;

import com.example.parkbookingslot.R;

public class ProfileFragment extends Fragment {

private ProfileViewModel profileViewModel;

public View onCreateView(@NonNull LayoutInflater inflater,
                         ViewGroup container, Bundle savedInstanceState) {
    profileViewModel =
            ViewModelProviders.of( this ).get( ProfileViewModel.class );
    View root = inflater.inflate( R.layout.fragment_profile, container, false );

    final TextView textView = root.findViewById( R.id.text_profile );

    profileViewModel.getText().observe( getViewLifecycleOwner(), new Observer<String>() {
        @Override
        public void onChanged(@Nullable String s) {
            textView.setText( s );
        }
    } );

    return root;
}

}

fragment_profile.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ui.profile.ProfileFragment">

<TextView
    android:id="@+id/email"
    android:layout_width="84dp"
    android:layout_height="31dp"
    android:layout_marginEnd="164dp"
    android:layout_marginRight="164dp"
    android:layout_marginBottom="182dp"
    android:text="Email"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent" />

<TextView
    android:id="@+id/text_profile"
    android:layout_width="109dp"
    android:layout_height="35dp"
    android:layout_marginEnd="150dp"
    android:layout_marginRight="150dp"
    android:layout_marginBottom="35dp"
    android:text="Your Profile"
    app:layout_constraintBottom_toTopOf="@+id/name"
    app:layout_constraintEnd_toEndOf="parent" />

<TextView
    android:id="@+id/name"
    android:layout_width="84dp"
    android:layout_height="31dp"
    android:layout_marginEnd="164dp"
    android:layout_marginRight="164dp"
    android:layout_marginBottom="34dp"
    android:text="Name"
    app:layout_constraintBottom_toTopOf="@+id/phoneno"
    app:layout_constraintEnd_toEndOf="parent" />

<TextView
    android:id="@+id/phoneno"
    android:layout_width="wrap_content"
    android:layout_height="31dp"
    android:layout_marginEnd="158dp"
    android:layout_marginRight="158dp"
    android:layout_marginBottom="36dp"
    android:text="Phone Number"
    app:layout_constraintBottom_toTopOf="@+id/vehicleno"
    app:layout_constraintEnd_toEndOf="parent" />

<TextView
    android:id="@+id/vehicleno"
    android:layout_width="112dp"
    android:layout_height="35dp"
    android:layout_marginEnd="150dp"
    android:layout_marginRight="150dp"
    android:layout_marginBottom="30dp"
    android:text="Vehicle Number"
    app:layout_constraintBottom_toTopOf="@+id/email"
    app:layout_constraintEnd_toEndOf="parent" />

Answer 1

ViewModel

import androidx.lifecycle.LiveData;
import androidx.lifecycle.MutableLiveData;
import androidx.lifecycle.ViewModel;

public class ProfileViewModel extends ViewModel {

      public LiveData<UserProfile> getUserProfile(){

        final MutableLiveData<UserProfile> userProfileMutableLiveData = new MutableLiveData<>();
        FirebaseFirestore db = FirebaseFirestore.getInstance();
        DocumentReference docRef = db.collection("users").document("[e-mail]");
        docRef.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
            @Override
            public void onComplete(@NonNull Task<DocumentSnapshot> task) {
                if (task.isSuccessful()) {
                    DocumentSnapshot document = task.getResult();
                    if (document != null && document.exists()) {
                        UserProfile userProfile = document.toObject(UserProfile.class);
                        userProfileMutableLiveData.postValue(userProfile);
                    } else {
                        userProfileMutableLiveData.postValue(null);
                    }
                } else {
                    userProfileMutableLiveData.postValue(null);
                }
            }
        });

        return userProfileMutableLiveData;
    }
}

片段

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.Observer;
import androidx.lifecycle.ViewModelProviders;

import com.example.parkbookingslot.R;

public class ProfileFragment extends Fragment {

private ProfileViewModel profileViewModel;

public View onCreateView(@NonNull LayoutInflater inflater,
                         ViewGroup container, Bundle savedInstanceState) {

    View root = inflater.inflate( R.layout.fragment_profile, container, false );

    profileViewModel =  ViewModelProviders.of(this).get(ProfileViewModel.class);

    profileViewModel.getUserProfile().observe(getViewLifecycleOwner(),new Observer<UserProfile>(){
         @Override
         public void onChanged(UserProfile userProfile) {
                if(userProfile != null){
                    //UPDATE YOUR UI HERE
                } else {
                    //SHOW ERROR MESSAGE
                }
         }
    });

    return root;
}

用户个人资料模型

public class UserProfile {
    String fullName, address, gender, phone;

    public String getFullName() {
        return fullName;
    }

    public void setFullName(String fullName) {
        this.fullName = fullName;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }
}

Firestore视图