在Firebase數據庫中讀取和寫入數據

注意： - 由於英語不是我的母語，所以對不起我的英語很糟糕，因爲我已經使用谷歌翻譯器。在Firebase數據庫中讀取和寫入數據

我正在開發一個android地圖應用程序，其中用戶可以找到他們朋友的當前位置並存儲當前位置我正在使用FireBase實時數據庫。因此，當用戶點擊查找按鈕時，他們朋友的當前位置將以其用戶名位於地圖上。

但我無法解決一個問題，當我試圖從Firebase中獲取用戶數據時。它沒有以正確的方式反映出來。數據被反映在2條不同的線在日誌中：

第1行： - 緯度&經度爲0.0但電子郵件是顯示並在
第2行： - 緯度&經度被正確地反映，但電子郵件是空

我不知道如何在一行中得到兩個。我在谷歌上搜索了很多，但失敗了。請幫助我瞭解如何以正確的方式完成。

下面是我的代碼和android studio屏幕截圖。

MainActivity.java

findfriend.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      startActivity(new Intent(MainActivity.this, MapsActivity.class)); 
     } 
    }); 

    final TextView tname; 
    tname = (TextView) findViewById(R.id.textview); 

    ref = FirebaseDatabase.getInstance().getReferenceFromUrl("https://ffinder-b4617.firebaseio.com/Email"); 
    mReferece2 = ref.child("email"); 
    mReferece2 = ref.child("location"); 

    proceed.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 

      ref.addValueEventListener(new ValueEventListener() { 
       @Override 
       public void onDataChange(DataSnapshot dataSnapshot) { 
        for (DataSnapshot dataSnapshot1: dataSnapshot.getChildren()){ 
         UserInformation details = dataSnapshot1.getValue(UserInformation.class); 

         String email = details.email; 
         Double lat = details.latitude; 
         Double lon = details.longitude; 
         tname.setText(lat+" "+'\n'+lon+'\n'+email); 

         System.out.println("-->"+ lat+" " + lon+" "+ email); 
        } 
       } 

       @Override 
       public void onCancelled(DatabaseError databaseError) { 

       } 
      }); 

     } 
    }); 
}

MapsActivity.java

@Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_maps); 
     Firebase.setAndroidContext(this); 

     if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) { 
      checkLocationPermission(); 
     } 

     //Check if Google Play Services Available or not 
     if (!CheckGooglePlayServices()) { 
      Log.d("onCreate", "Finishing test case since Google Play Services are not available"); 
      finish(); 
     } else { 
      Log.d("onCreate", "Google Play Services available."); 
     } 

     auth = FirebaseAuth.getInstance(); 

     // Obtain the SupportMapFragment and get notified when the map is ready to be used. 
     SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager() 
       .findFragmentById(R.id.map); 
     mapFragment.getMapAsync(this); 

FirebaseDatabase.getInstance().getReference().child("Location"); 
    } 

    @Override 
    public void onLocationChanged(Location location) { 
     Log.d("onLocationChanged", "entered"); 

     mLastLocation = location; 

     DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss"); 
     dateFormat.setTimeZone(TimeZone.getTimeZone("UTC")); 
     Date date = new Date(); 
     mLastUpdateTime = ((dateFormat.format(date).toString())); 

     saveToFirebase(); 

     if (mCurrLocationMarker != null) { 
      mCurrLocationMarker.remove(); 
     } 

     latitude = location.getLatitude(); 
     longitude = location.getLongitude(); 

     LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude()); 
     MarkerOptions markerOptions = new MarkerOptions(); 
     markerOptions.position(latLng); 
     markerOptions.draggable(true); 
     markerOptions.title("Current Position"); 
     markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_MAGENTA)); 
     mCurrLocationMarker = mMap.addMarker(markerOptions); 
     mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng)); 
     mMap.animateCamera(CameraUpdateFactory.zoomTo(11)); 

     Toast.makeText(MapsActivity.this,"Your Current Location", Toast.LENGTH_LONG).show(); 

     //stop location updates 
     if (mGoogleApiClient != null) { 
      LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this); 
      Log.d("onLocationChanged", "Removing Location Updates"); 
     } 

    } 

    public void saveToFirebase() { 

     Firebase firebase = new Firebase("https://ffinder-b4617.firebaseio.com").child("Email").child("location"); 

     Map mLoactions = new HashMap(); 
     mLoactions.put("timestamp",mLastUpdateTime); 
     mLoactions.put("latitude", mLastLocation.getLatitude()); 
     mLoactions.put("longitude", mLastLocation.getLongitude()); 

     firebase.setValue(mLoactions); 
    } 

    @Override 
    public void onConnectionFailed(ConnectionResult connectionResult) { 
} 

    public static final int MY_PERMISSIONS_REQUEST_LOCATION = 99; 
    public boolean checkLocationPermission(){ 
     if (ContextCompat.checkSelfPermission(this, 
       Manifest.permission.ACCESS_FINE_LOCATION) 
       != PackageManager.PERMISSION_GRANTED) { 

      // Asking user if explanation is needed 
      if (ActivityCompat.shouldShowRequestPermissionRationale(this, 
        Manifest.permission.ACCESS_FINE_LOCATION)) { 

       ActivityCompat.requestPermissions(this, 
         new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 
         MY_PERMISSIONS_REQUEST_LOCATION); 


      } else { 
       // No explanation needed, we can request the permission. 
       ActivityCompat.requestPermissions(this, 
         new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 
         MY_PERMISSIONS_REQUEST_LOCATION); 
      } 
      return false; 
     } else { 
      return true; 
     } 
    } 

    @Override 
    public void onRequestPermissionsResult(int requestCode, 
              String permissions[], int[] grantResults) { 
     switch (requestCode) { 
      case MY_PERMISSIONS_REQUEST_LOCATION: { 
       // If request is cancelled, the result arrays are empty. 
       if (grantResults.length > 0 
         && grantResults[0] == PackageManager.PERMISSION_GRANTED) { 

        if (ContextCompat.checkSelfPermission(this, 
          Manifest.permission.ACCESS_FINE_LOCATION) 
          == PackageManager.PERMISSION_GRANTED) { 

         if (mGoogleApiClient == null) { 
          buildGoogleApiClient(); 
         } 
         mMap.setMyLocationEnabled(true); 
        } 

       } else { 

        // Permission denied, Disable the functionality that depends on this permission. 
        Toast.makeText(this, "permission denied", Toast.LENGTH_LONG).show(); 
       } 
       return; 
      } 
     } 
    } 

    @Override 
    public boolean onMarkerClick(Marker marker) { 
     marker.setDraggable(true); 
     return false; 
    } 

    @Override 
    public void onMarkerDragStart(Marker marker) {} 

    @Override 
    public void onMarkerDrag(Marker marker) {} 

    @Override 
    public void onMarkerDragEnd(Marker marker) { 
     end_latitude = marker.getPosition().latitude; 
     end_longitude = marker.getPosition().longitude; 

     Log.d("end_lat",""+end_latitude); 
     Log.d("end_lng",""+end_longitude); 
    } 
}

Login.class

@Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_login); 
     Firebase.setAndroidContext(this); 

     auth = FirebaseAuth.getInstance(); 

     if (auth.getCurrentUser() != null){ 
      startActivity(new Intent(LoginActivity.this, MainActivity.class)); 
      finish(); 
     } 

     setContentView(R.layout.activity_login); 

     inputEmail = (EditText) findViewById(R.id.email); 
     inputPassword = (EditText) findViewById(R.id.password); 
     progressBar = (ProgressBar) findViewById(R.id.progressBar); 
     btnSignup = (Button) findViewById(R.id.btn_signup); 
     btnLogin = (Button) findViewById(R.id.btn_login); 
     btnReset = (Button) findViewById(R.id.btn_reset_password); 

     auth = FirebaseAuth.getInstance(); 

     btnSignup.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       startActivity(new Intent(LoginActivity.this, SignupActivity.class)); 
      } 
     }); 

     btnReset.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       startActivity(new Intent(LoginActivity.this, ResetPasswordActivity.class)); 
      } 
     }); 

     btnLogin.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 

       String email = inputEmail.getText().toString(); 
       final String password = inputPassword.getText().toString(); 

       if (TextUtils.isEmpty(email)) { 
        Toast.makeText(getApplicationContext(), "Enter email address!", Toast.LENGTH_SHORT).show(); 
        return; 
       } 

       if (TextUtils.isEmpty(password)) { 
        Toast.makeText(getApplicationContext(), "Enter password!", Toast.LENGTH_SHORT).show(); 
        return; 
       } 
     progressBar.setVisibility(View.VISIBLE); 

       //authenticate user 
       auth.signInWithEmailAndPassword(email, password) 
         .addOnCompleteListener(LoginActivity.this, new OnCompleteListener<AuthResult>() { 
          @Override 
          public void onComplete(@NonNull Task<AuthResult> task) { 

           progressBar.setVisibility(View.GONE); 
           if (!task.isSuccessful()) { 
            // there was an error 
            if (password.length() < 6) { 
             inputPassword.setError(getString(R.string.minimum_password)); 
            } else { 
             Toast.makeText(LoginActivity.this, getString(R.string.auth_failed), Toast.LENGTH_LONG).show(); 
            } 
           } else { 
            Intent intent = new Intent(LoginActivity.this, MainActivity.class); 
            startActivity(intent); 
            finish(); 
     } 
     } 
    }); 
    } 
}); 
} 

    public void userLoginInfo(){ 

     String email = inputEmail.getText().toString(); 

     mDatabase = FirebaseDatabase.getInstance().getReference().child("Email").push(); 
     String userId = mDatabase.child("email").getKey(); 
     mDatabase.child(userId).setValue(email); 
    } 
}

個UserInformation.class

public class UserInformation { 

    public String email; 
    public double latitude; 
    public double longitude; 

    public UserInformation() { 
    } 

    public UserInformation(String email, double latitude, double longitude) { 
     this.email = email; 
     this.latitude = latitude; 
     this.longitude = longitude; 
    } 

    public String getEmail() { 
     return email; 
    } 

    public double getLatitude() { 
     return latitude; 
    } 

    public double getLongitude() { 
     return longitude; 
    } 
}

火力地堡數據庫截圖 Android Studio中的日誌截圖

來源

2017-10-12 Amit Rana

你userLoginInfo()方法使用push()來在數據庫中創建一個唯一的密鑰存儲的電子郵件地址，並您的saveToFirebase()方法不同地存儲緯度/經度值，這意味着數據在不同的地方結束。

這將有利於充分利用你的UserInformation對象的標準化數據庫，並使用DatabaseReference#setValue(Object) 和DataSnapshot#getValue(Class<CT>)來存儲和檢索數據。所以，當你要存儲用戶的位置，你這樣做：

public void saveToFirebase() { 
    DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("Email").push(); 

    String email = FirebaseAuth.getInstance().getCurrentUser().getEmail(); 

    UserInformation userInformation = new UserInformation(email, mLastLocation.getLatitude(), mLastLocation.getLongitude()); 

    ref.setValue(userInformation); 
}

然後，再取回這些細節，您可以使用您現有的ValueEventListener了一些調整：

DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("Email"); 

ref.addValueEventListener(new ValueEventListener() { 
    @Override 
    public void onDataChange(DataSnapshot dataSnapshot) { 
     for (DataSnapshot child : dataSnapshot.getChildren()){ 
      UserInformation details = child.getValue(UserInformation.class); 

      System.out.println("-->" + details.getLatitude() +" " + details.getLongitude() +" "+ details.getEmail()); 
     } 
    } 

    @Override 
    public void onCancelled(DatabaseError databaseError) {} 
});

我希望我」我已經正確理解您的要求，請讓我知道我是否遺漏了任何東西。

來源

2017-10-12 10:03:25 Grimthorr

感謝您的回覆，它幫助我組織單親「電子郵件」下的數據，但現在我沒有在Firebase中獲取用戶的登錄電子郵件。 –

它是未來像這樣如下： - 。 ffinder-b4617 電子郵件郵件：「電子郵件」緯度：31.5037501 經度：74.3502436 –

你可以用'FirebaseAuth.getInstance（）getCurrentUser（）getEmail（）'以獲得當前用戶的電子郵件地址，因此您可以在'saveToFirebase（）'方法中使用它。這會起作用嗎？ – Grimthorr

在Firebase數據庫中讀取和寫入數據

回答

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