Question

我有一个向用户显示图片的应用。这听起来很简单，但我已经在这几天试图解决确切的问题。那么，用户将会发生什么：

点击图片;
图像将保存到用户的外部存储;
图像的Uri将被拍摄;
ImageView将使用此Uri打开图像;
没有图片出现，抛出java.io.FileNotFoundException: /storage/emulated/....jpg: open failed: ENOENT (No such file or directory)。

所以我认为我并没有真正通过正确的Uri，并试图从那里进行故障排除。然后我不小心旋转屏幕嘿 - 我的形象就在那里！当我将它旋转几次时，日志文件显示了这一点：

android.graphics.Bitmap@49361a20
android.graphics.Bitmap@495c42c8
android.graphics.Bitmap@496ac1e0
android.graphics.Bitmap@495b2b28

这是否显示内存位置？即使在屏幕旋转后，它应该是不同的吗？

有了这些信息，我还有其他地方可以解决这个问题吗？我可以排除Uri无效，因为它在旋转屏幕后显示正确的图像。

这是下载单击图像所涉及的代码（实用程序类）; 此方法似乎运行良好，图像保存到正确的目录。

 public void downloadFile(String url) {
        File folder  = new File(Environment.getExternalStorageDirectory() + directory);
        String fileName = url.substring(url.lastIndexOf("/") + 1);
        String filePath = folder.getPath() + "/" + fileName;
        File file = new File(filePath);
        fileUri = Uri.fromFile(file);

        if (!folder.exists()) {
            Log.i(TAG, "Worka folder is not found, creating one now");
            folder.mkdir();
        } else {
            Log.i(TAG, "Worka folder is found");
            if (file.exists()) {
                Log.i(TAG, "Found a file with the same name, deleting/replacing it now");
                file.delete();
            }
        }

        DownloadManager downloadManager = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);

        Uri downloadUri = Uri.parse(url);
        DownloadManager.Request request = new DownloadManager.Request(downloadUri);

        request.setAllowedNetworkTypes(
                DownloadManager.Request.NETWORK_MOBILE | DownloadManager.Request.NETWORK_WIFI)
                //.setAllowedOverRoaming(false).setTitle("Roaming is not available")
                .setDestinationInExternalPublicDir(directory, fileName);

        downloadManager.enqueue(request);
        Log.i(TAG, "downloadFile() is successful, " + fileName + " is saved to Worka directory");
}

public Uri getFilePath() {
        return fileUri;
}

确保它从活动传递到另一个活动;

FileDownload fileDownload = new FileDownload(getApplicationContext());
                fileDownload.downloadFile(conversation.getMessage());
                Uri fileUri = fileDownload.getFilePath();

                if (fileUri != null) {
                    Log.i(TAG, "fileUri: " + fileUri.toString());
                    Intent intent = new Intent(BulletinPostActivity.this, ImageViewingActivity.class);
                    intent.putExtra("imageUri", fileUri.toString());
                    startActivity(intent);

最后，从传递的Uri中获取Bitmap：

然后我尝试在这里使用AsyncTask，以确保位图正确加载......但我不确定要编写什么来实现此目的。

 public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ...

    String imagePath = getIntent().getStringExtra("imageUri");
    imageUri = Uri.parse(imagePath);

    touchImageView = (TouchImageView) findViewById(R.id.image_viewing_image_view);

    if (imageUri != null) {
        new loadBitmap(imageUri).execute();
    }
}

public class loadBitmap extends AsyncTask<Void, Integer, Bitmap> {

    Uri uri;

    public loadBitmap(Uri uri) {
        this.uri = uri;
    }

    @Override
    protected Bitmap doInBackground(Void... params) {
        getBitmap();
        return bitmap;
    }

    public Bitmap getBitmap() {
        try {
            Log.i(TAG, "Attempting to get the bitmap from imageUri");
            bitmap = MediaStore.Images.Media.getBitmap(getContentResolver(), imageUri);
            Log.i(TAG, "Successfully gotten the bitmap from imageUri: " + bitmap);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return bitmap;
    }

    @Override
    protected void onPostExecute(Bitmap bitmap) {
        if (bitmap == null) {
            getBitmap();
        } else {
            touchImageView.setImageBitmap(bitmap);
        }
    }
}

来自Uri的ImageView仅在旋转屏幕后出现

0 个答案: