Android实现带身份验证的Camera Intent图片上传至Firebase

Hey there! Let's get your authenticated Firebase image upload working smoothly. I've looked over your code and spotted a few key gaps and outdated methods that are holding this back—let's fix them step by step:

Key Fixes & Improvements #

• Initialize your Storage Reference properly
  You declared mstorageRef but never assigned it a value, which will cause a NullPointerException when you try to upload. Add this line in your onCreate method:

  mstorageRef = FirebaseStorage.getInstance().getReference();
  

• Update the Download URL retrieval method
  The old taskSnapshot.getDownloadUrl() is deprecated. Instead, fetch the URL from the storage reference after a successful upload.

• Add null safety for the captured Bitmap
  If the user taps "submit" without taking a photo first, photo will be null and crash your app. Add a check at the start of the submit method.

• Optional: Save the image URL to Firebase Realtime Database
  Since you already have a database reference, storing the download URL alongside the user's profile info makes it easy to access later.

Corrected Full Code #

package com.example.android.besafe; 

import android.app.Activity; 
import android.content.Intent; 
import android.graphics.Bitmap; 
import android.net.Uri; 
import android.provider.MediaStore; 
import android.support.annotation.NonNull; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.ImageButton; 
import android.widget.Toast; 

import com.google.android.gms.tasks.OnFailureListener; 
import com.google.android.gms.tasks.OnSuccessListener; 
import com.google.firebase.auth.FirebaseAuth; 
import com.google.firebase.auth.FirebaseUser; 
import com.google.firebase.database.DatabaseReference; 
import com.google.firebase.database.FirebaseDatabase; 
import com.google.firebase.storage.FirebaseStorage; 
import com.google.firebase.storage.StorageReference; 
import com.google.firebase.storage.UploadTask; 

import java.io.ByteArrayOutputStream; 
import java.util.HashMap; 
import java.util.Map; 

public class CameraActivity extends AppCompatActivity { 
    private ImageButton mProfileImage; 
    Bitmap photo; 
    private static final int CAMERA_REQ = 1; 
    StorageReference mstorageRef; 
    String userId; 
    private FirebaseAuth mAuth; 
    FirebaseUser firebaseUser; 
    FirebaseDatabase firebaseDatabase; 
    DatabaseReference ref; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.activity_camera); 

        mProfileImage = findViewById(R.id.btnselect); 
        firebaseDatabase = FirebaseDatabase.getInstance(); 
        ref = firebaseDatabase.getReference("ProfileInfo"); 
        mAuth = FirebaseAuth.getInstance(); 
        firebaseUser = mAuth.getCurrentUser(); 
        userId = firebaseUser.getUid(); 

        // Initialize Storage Reference (FIXED)
        mstorageRef = FirebaseStorage.getInstance().getReference();

        mProfileImage.setOnClickListener(new View.OnClickListener() { 
            @Override 
            public void onClick(View v) { 
                Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); 
                startActivityForResult(cameraIntent, CAMERA_REQ); 
            } 
        }); 
    } 

    public void submit(View v){ 
        // Add null check for captured photo (FIXED)
        if (photo == null) {
            Toast.makeText(this, "Please take a photo first!", Toast.LENGTH_SHORT).show();
            return;
        }

        ByteArrayOutputStream stream = new ByteArrayOutputStream(); 
        photo.compress(Bitmap.CompressFormat.JPEG, 100, stream); 
        byte[] b = stream.toByteArray(); 

        StorageReference storageReference = mstorageRef.child("documentImages")
                .child(userId)
                .child("noplateImg"); 

        storageReference.putBytes(b)
                .addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() { 
                    @Override 
                    public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) { 
                        // Fetch download URL using updated method (FIXED)
                        taskSnapshot.getStorage().getDownloadUrl()
                                .addOnSuccessListener(new OnSuccessListener<Uri>() { 
                                    @Override 
                                    public void onSuccess(Uri downloadUri) { 
                                        Toast.makeText(CameraActivity.this, "Upload successful!", Toast.LENGTH_LONG).show();

                                        // Optional: Save URL to Realtime Database
                                        Map<String, Object> profileUpdates = new HashMap<>();
                                        profileUpdates.put("profileImageUrl", downloadUri.toString());
                                        ref.child(userId).updateChildren(profileUpdates)
                                                .addOnSuccessListener(new OnSuccessListener<Void>() {
                                                    @Override
                                                    public void onSuccess(Void aVoid) {
                                                        Toast.makeText(CameraActivity.this, "Image URL saved to database!", Toast.LENGTH_SHORT).show();
                                                    }
                                                });
                                    } 
                                }); 
                    } 
                }) 
                .addOnFailureListener(new OnFailureListener() { 
                    @Override 
                    public void onFailure(@NonNull Exception e) { 
                        Toast.makeText(CameraActivity.this,"Upload failed: " + e.getMessage(),Toast.LENGTH_LONG).show(); 
                    } 
                }); 
    } 

    @Override 
    public void onActivityResult(int requestCode, int resultCode, Intent data) { 
        super.onActivityResult(requestCode, resultCode, data); // Don't forget to call super!
        if (requestCode == CAMERA_REQ && resultCode == RESULT_OK) { 
            photo = (Bitmap) data.getExtras().get("data"); 
            // Optional: Uncomment to preview the captured photo
            // ImageView preview = findViewById(R.id.imageview);
            // preview.setImageBitmap(photo);
        } 
    } 
}

Quick Extra Notes #

• Thumbnail vs Full-Resolution: The bitmap from data.getExtras().get("data") is a low-res thumbnail. If you need full-size images, you'll need to use a File Provider to capture the image directly to a file instead. Just let me know if you want to expand on that!
• Permissions: Ensure you have the CAMERA permission (and storage permissions for older Android versions) declared in your AndroidManifest.xml.
• Auth Safety: Add a check for firebaseUser != null at the start of onCreate to handle cases where the user signs out while the activity is active.

内容的提问来源于stack exchange，提问作者AHMED ABBAS