Question

我正在尝试创建一个应用程序，您可以在按钮单击时从库中选择图像，选择图像后，应将其保存在firebase上，然后在我的活动中检索回来。问题是我已经成功保存了我的firebase数据库中的图像，但是当我的应用程序启动时，它没有在我的ImageView中显示图像。

以下是我的java代码。我做错了请帮帮我

public class MainActivity extends AppCompatActivity {

private static int RESULT_LOAD_IMG = 1;
String imgDecodableString;
Firebase ref;
ImageView imgView;
String encodedImage;

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

     ref = new Firebase("https://setfireimage.firebaseio.com");

      imgView = (ImageView) findViewById(R.id.imgView);

    byte[] dec = Base64.decode(encodedImage,Base64.DEFAULT);
    Bitmap decodeByte = BitmapFactory.decodeByteArray(dec,0,dec.length);
    imgView.setImageBitmap(decodeByte);


}

public void loadImagefromGallery(View view) {
    // Create intent to Open Image applications like Gallery, Google Photos
    Intent galleryIntent = new Intent(Intent.ACTION_PICK,
            android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
    // Start the Intent
    startActivityForResult(galleryIntent, RESULT_LOAD_IMG);
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    try{
        if (requestCode == RESULT_LOAD_IMG && resultCode == RESULT_OK
                && null != data) {
            // Get the Image from data

            Uri selectedImage = data.getData();
            String[] filePathColumn = { MediaStore.Images.Media.DATA };

            // Get the cursor
            Cursor cursor = getContentResolver().query(selectedImage,
                    filePathColumn, null, null, null);
            // Move to first row
            cursor.moveToFirst();

            int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
            imgDecodableString = cursor.getString(columnIndex);
            cursor.close();



            Bitmap bm = BitmapFactory.decodeFile(imgDecodableString);
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            bm.compress(Bitmap.CompressFormat.JPEG,100,baos);
            byte[] byteArray =  baos.toByteArray();
            String encodedImage = Base64.encodeToString(byteArray,Base64.DEFAULT);

                ref.push().setValue(encodedImage, new Firebase.CompletionListener() {
                    @Override
                    public void onComplete(FirebaseError firebaseError, Firebase firebase) {

                        if(firebaseError != null){
                            Toast.makeText(getApplicationContext(),firebaseError.getMessage(),Toast.LENGTH_SHORT).show();
                        }
                        else{
                            Toast.makeText(getApplicationContext(),"Image Saved",Toast.LENGTH_SHORT).show();
                        }
                    }
                });

        } else {
            Toast.makeText(this, "You haven't picked Image",
                    Toast.LENGTH_LONG).show();
        }
    }
    catch (Exception e) {
        Toast.makeText(this, "Something went wrong", Toast.LENGTH_LONG)
                .show();
    }

   }
}

XML代码：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="random.setimagefirebase.MainActivity"
android:orientation="vertical">


<ImageView
    android:id="@+id/imgView"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1" >
</ImageView>

<Button
    android:id="@+id/buttonLoadPicture"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:onClick="loadImagefromGallery"
    android:text="Load Picture" >
</Button>


</LinearLayout>

Answer 1

基本上，你想要做的是这样的事情：

在Activity中创建一个常量，该常量将对应此图像的子名称：

private final String IMAGE = "image";

然后，在你的onCreate中你需要做这样的事情：

ref.child(IMAGE).addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            String data = dataSnapshot.getValue(String.class);
            if(data != null) {
                byte[] dec = Base64.decode(data,Base64.DEFAULT);
                Bitmap decodeByte = BitmapFactory.decodeByteArray(dec,0,dec.length);
                imgView.setImageBitmap(decodeByte);
            }
        }

        @Override
        public void onCancelled(FirebaseError firebaseError) {

        }
    });

当您在FireBase中创建此值时，您需要这样做：

 mFirebaseRef.child(IMAGE).setValue(encodedImage, new Firebase.CompletionListener() {
        @Override
        public void onComplete(FirebaseError firebaseError, Firebase firebase) {

            if(firebaseError != null){
                Toast.makeText(getApplicationContext(),firebaseError.getMessage(),Toast.LENGTH_SHORT).show();
            }
            else{
                Toast.makeText(getApplicationContext(),"Image Saved",Toast.LENGTH_SHORT).show();
            }
        }
    });

而不是

ref.push().setValue(encodedImage, new Firebase.CompletionListener() {
                    @Override
                    public void onComplete(FirebaseError firebaseError, Firebase firebase) {

                        if(firebaseError != null){
                            Toast.makeText(getApplicationContext(),firebaseError.getMessage(),Toast.LENGTH_SHORT).show();
                        }
                        else{
                            Toast.makeText(getApplicationContext(),"Image Saved",Toast.LENGTH_SHORT).show();
                        }
                    }
                });

因此，当您更改它时，它会自动调用onDataChanged

中的onCreate

无法在imageview中检索Firebase图像

1 个答案: