我想从Firebase数据库获取数据并将其放在对象中。 我可以看到我正确访问了数据库中的数据，但是无法将其放入我的对象中。
FirebaseMethods
package com.example.android.instagramclone.Utils;
import android.content.Context;
import android.support.annotation.NonNull;
import android.util.Log;
import android.view.View;
import android.widget.ProgressBar;
import android.widget.Toast;
import com.example.android.instagramclone.R;
import com.example.android.instagramclone.models.User;
import com.example.android.instagramclone.models.UserAccountSettings;
import com.example.android.instagramclone.models.UserSettings;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
public class FirebaseMethods {
private static final String TAG = "FirebaseMethods";
private Context mContext;
//Firebase
private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListener;
private FirebaseDatabase database;
private DatabaseReference reference;
private String userid;
/**
* constructor
*
* @param mContext
*/
public FirebaseMethods(Context mContext) {
mAuth = FirebaseAuth.getInstance();
//initialize database.
database = FirebaseDatabase.getInstance();
reference = database.getReference();
this.mContext = mContext;
if (mAuth.getCurrentUser() != null) {
//userID is unique to each user.
userid = mAuth.getCurrentUser().getUid();
}
}
/**
* add information to the users nodes.
* add information to the account setting node.
*
* @param username
* @param email
* @param description
* @param website
* @param profile_photo
*/
public void addNewUser(String username, String email, String description, String website, String profile_photo) {
//setting up user personal info.
User user = new User(StringManupulation.condenseUsername(username), 1, email, username);
//reference a node;
reference.child(mContext.getString(R.string.dbname_users)).child(userid).setValue(user);
//setting up userAccountSetting
UserAccountSettings settings = new UserAccountSettings(
description,
username,
0,
0,
0,
"",
StringManupulation.condenseUsername(username),
website
);
reference.child(mContext.getString(R.string.dbname_user_account_settings))
.child(userid)
.setValue(settings);
}
/**
* setting up FirebaseAuthentificationListener.
*/
private void updateUI() {
Log.d(TAG, "updateUI: started.");
mAuthListener = new FirebaseAuth.AuthStateListener() {
@Override
public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
FirebaseUser user = firebaseAuth.getCurrentUser();
if (user != null) {
Log.d(TAG, "onAuthStateChanged: successfully logged in.");
} else {
Log.d(TAG, "onAuthStateChanged: authentification failed.");
}
}
};
}
/**
* retrieve the account settings from Forebase database.
*
* @param dataSnapshot
* @return
*/
public UserSettings getUserSettings(DataSnapshot dataSnapshot) {
Log.d(TAG, "getUserAccountSettings: retrieving user acoount settings from firebase.");
UserAccountSettings settings = new UserAccountSettings();
User user = new User();
//Read through all the major nodes.
for (DataSnapshot ds : dataSnapshot.getChildren()) {
// If the name of a node is "user_account_setings".
if (ds.getKey().equals(mContext.getString(R.string.dbname_user_account_settings))) {
Log.d(TAG, "getUserAccountSettings: datasnapshot: "+ ds);
try {
//Setting display_name.
settings.setDisplay_name(ds.child(userid)
.getValue(UserAccountSettings.class)
.getDisplay_name());
Log.d(TAG, "getUserSettings: " + settings.getDisplay_name());
//Setting username.
settings.setUsername(ds.child(userid)
.getValue(UserAccountSettings.class)
.getUsername());
//Setting website.
settings.setWebsite(ds.child(userid)
.getValue(UserAccountSettings.class)
.getWebsite());
//Setting description.
settings.setDescription(ds.child(userid)
.getValue(UserAccountSettings.class)
.getDescription());
//Setting profile_photo.
settings.setProfile_photo(ds.child(userid)
.getValue(UserAccountSettings.class)
.getProfile_photo());
//Setting posts.
settings.setPost(ds.child(userid)
.getValue(UserAccountSettings.class)
.getPost());
//Setting followers.
settings.setFollowers(ds.child(userid)
.getValue(UserAccountSettings.class)
.getFollowers());
//Setting Followings.
settings.setFollowing(ds.child(userid)
.getValue(UserAccountSettings.class)
.getFollowing());
Log.d(TAG, "getUserAccountSettings: retrieved user_account_settings info.");
} catch (NullPointerException e) {
Log.e(TAG, "getUserAccountSettings: " + e.getMessage());
}
//users node
if (ds.getKey().equals(R.string.dbname_users)) {
Log.d(TAG, "getUserAccountSettings: dataSnapShot: " + ds);
try {
//Setting mail.
user.setMail(ds.child(userid)
.getValue(User.class)
.getMail());
//Setting username.
user.setUsername(ds.child(userid)
.getValue(User.class)
.getUsername());
//Setting phone_number.
user.setPhone_number(ds.child(userid)
.getValue(User.class)
.getPhone_number());
//Setting userID.
user.setUserID(ds.child(userid)
.getValue(User.class)
.getUserID());
Log.d(TAG, "getUserAccountSettings: retrieved user info.");
} catch (NullPointerException e) {
Log.e(TAG, "getUserAccountSettings: " + e.getMessage());
}
}
}
}
return new UserSettings(user, settings);
}
}
个人资料片段
package com.example.android.instagramclone.Profile;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.design.widget.BottomNavigationView;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.TextView;
import com.example.android.instagramclone.R;
import com.example.android.instagramclone.Utils.BottomNavigationViewHelper;
import com.example.android.instagramclone.Utils.FirebaseMethods;
import com.example.android.instagramclone.Utils.GridImageAdapter;
import com.example.android.instagramclone.Utils.UniversalImageLoader;
import com.example.android.instagramclone.models.User;
import com.example.android.instagramclone.models.UserAccountSettings;
import com.example.android.instagramclone.models.UserSettings;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;
import java.util.ArrayList;
import de.hdodenhof.circleimageview.CircleImageView;
public class ProfileFragment extends Fragment {
private static final String TAG = "ProfileFragment";
private Context mContext;
private TextView mPosts;
private TextView mFollowers;
private TextView mFollowings;
private TextView mDisplayName;
private TextView mUserName;
private TextView mWebsite;
private TextView mDescription;
private ProgressBar mProgressBar;
private CircleImageView mProfilePhoto;
private GridView gridView;
private ImageView profileMenu;
private android.support.v7.widget.Toolbar toolbar;
private BottomNavigationView bottomNavigationView;
//For bottomNavigationView icons.
private static final int ACTIVITY_NUM = 4;
//The number of columns of gridView for pics uploaded.
private static final int NUM_GRID_COLUMNS = 3;
//Firebase things.
private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListener;
private FirebaseDatabase database;
private DatabaseReference myRef;
private FirebaseMethods mFirebaseMethods;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_profile, container, false);
Log.d(TAG, "onCreateView: started.");
//Setting up each widgets.
mDisplayName = (TextView) view.findViewById(R.id.display_name);
mUserName = (TextView) view.findViewById(R.id.username);
mPosts = (TextView) view.findViewById(R.id.tv_posts);
mFollowings = (TextView) view.findViewById(R.id.tvFollowing);
mFollowers = (TextView) view.findViewById(R.id.tvFollowers);
mWebsite = (TextView) view.findViewById(R.id.display_website);
mDescription = (TextView) view.findViewById(R.id.display_description);
mProfilePhoto = (CircleImageView) view.findViewById(R.id.profile_image);
mProgressBar = (ProgressBar) view.findViewById(R.id.profileProgressBar);
gridView = (GridView) view.findViewById(R.id.gridview);
toolbar = (android.support.v7.widget.Toolbar) view.findViewById(R.id.profileToolBar);
profileMenu = (ImageView) view.findViewById(R.id.profile_menu);
bottomNavigationView = (BottomNavigationView) view.findViewById(R.id.bottomNavViewBar);
mContext = getActivity();
mFirebaseMethods = new FirebaseMethods(getActivity());
//setting up progress bar
mProgressBar.setVisibility(View.GONE);
setupBottomNavigationView();
setupToolbar();
setUpFirebaseAuth();
return view;
}
/**
* Setting up information retrieving from FIrebaseDatabase.
* @param userSettings
*/
private void setProfileWidgets(UserSettings userSettings){
//Create instances.
User user = userSettings.getUser();
UserAccountSettings accountSettings = userSettings.getSettings();
Log.d(TAG, "setProfileWidgets: Setting Widgets with data retrieving from firebaseDatabase: " + accountSettings.toString());
//Set values to each views.
UniversalImageLoader.setImage(accountSettings.getProfile_photo(), mProfilePhoto, null, "");
mDisplayName.setText(accountSettings.getDisplay_name());
mUserName.setText(accountSettings.getUsername());
mWebsite.setText(accountSettings.getWebsite());
mDescription.setText(accountSettings.getDescription());
mPosts.setText(String.valueOf(accountSettings.getPost()));
mFollowers.setText(String.valueOf(accountSettings.getFollowers()));
mFollowings.setText(String.valueOf(accountSettings.getFollowing()));
}
/**
* setting up the toolBar on the top.
*/
private void setupToolbar() {
//アクションバーとしてtoolbarを使う
((ProfileActivity) getActivity()).setSupportActionBar(toolbar);
// When the toolbar button is tapped, navigate to Account setting page.
profileMenu.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.d(TAG, "onClick: navigating to account settings.");
Intent intent = new Intent(mContext, AccountSettingActivity.class);
startActivity(intent);
}
});
}
/**
* set up bottomNavigationView
*/
private void setupBottomNavigationView() {
Log.d(TAG, "setBottomNavigationView: setting up bottomNavigationView");
BottomNavigationViewHelper.enableNavigation(mContext, bottomNavigationView);
Menu menu = bottomNavigationView.getMenu();
MenuItem menuItem = menu.getItem(ACTIVITY_NUM);
menuItem.setChecked(false);
}
/**
* -----------------Firebase section starts------------------------*
*/
/**
* Setting up FirebaseAuth for Authentification of user
*/
private void setUpFirebaseAuth() {
Log.d(TAG, "setUpFirebaseAuth: started.");
mAuth = FirebaseAuth.getInstance();
//Preparing to get info from FirebaseDatabase.
database = FirebaseDatabase.getInstance();
myRef = database.getReference();
mAuthListener = new FirebaseAuth.AuthStateListener() {
@Override
public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
FirebaseUser user = firebaseAuth.getCurrentUser();
if (user != null) {
Log.d(TAG, "onAuthStateChanged: User logged in.");
} else if (user == null) {
Log.d(TAG, "onAuthStateChanged: User not logged in.");
}
}
};
//Allow us to get data snapshot and read, write data.
myRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
//retrieve user info from database.
setProfileWidgets(mFirebaseMethods.getUserSettings(dataSnapshot));
//retrieve images for the user in question.
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
@Override
public void onStart() {
super.onStart();
Log.d(TAG, "onStart: started.");
//user Authentification and update UI accordingly.
setUpFirebaseAuth();
mAuth.addAuthStateListener(mAuthListener);
}
@Override
public void onStop() {
super.onStop();
Log.d(TAG, "onStop: started.");
if(mAuthListener != null ){
mAuth.removeAuthStateListener(mAuthListener);
}
}
/**
* -----------------Firebase section ends ------------------------*
*/
}
log.d正确显示了“ ds”的内容，这意味着我可以正确访问数据。但是，当我在对象“ accountSettings”中放入数据后看到每个值时，它显示String为null，长值（初始化值）为0。 您能告诉我为什么会发生这种情况以及如何解决这个问题吗？
谢谢。
答案 0 :(得分：0)
我不知道这是否有用，但这是我从Firebase设置数据的方式。
private DatabaseReference mUsernameDatabase;
//
mUsernameDatabase = FirebaseDatabase.getInstance().getReference().child("Users").child(current_uid);
mUsernameDatabase.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
String about = Objects.requireNonNull(dataSnapshot.child("about").getValue()).toString();
editAbout.setText(about);
String address = Objects.requireNonNull(dataSnapshot.child("address").getValue()).toString();
editAddress.setText(address);
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
Toast.makeText(Profile.this, databaseError.getMessage(), Toast.LENGTH_SHORT).show();
}
});
答案 1 :(得分：0)
谢谢，我解决了这个问题。 那是因为我已经删除了登录帐户。 不是因为我的代码。 但是我从您的答案中学到了很多。 再次感谢。