在android中使用URI获取文件大小

Question

我正在开发 android 视频应用程序，我正在使用 Camera Intent 录制视频并从图库中拍摄视频。录制视频时或从图库中选择视频后，我想知道我拍摄的视频的大小。如果选择的视频大小大于 5MB，我想创建一个逻辑来向用户显示吐司消息。我做了一个不工作的底层逻辑，并给了我 0 值，我试图从 URI 中获取大小。

提前致谢。

我的逻辑不起作用

java.net.URI juri = new java.net.URI(uri.toString());
        File mediaFile = new File(juri.getPath());
        long fileSizeInBytes = mediaFile.length();
        long fileSizeInKB = fileSizeInBytes / 1024;
        long fileSizeInMB = fileSizeInKB / 1024;

        if (fileSizeInMB > 5) {
            Toast.makeText(this,"Video files lesser than 5MB are allowed",Toast.LENGTH_LONG).show();
            return;
        }

这是我用来从图库获取视频并录制视频的代码。

public void takeVideoFromCamera(){

        File mediaFile =new File(Environment.getExternalStorageDirectory().getAbsolutePath()+ "/myvideo.mp4");

        Intent intent = new Intent(MediaStore.ACTION_VIDEO_CAPTURE);
        Uri videoUri;

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
//            videoUri = FileProvider.getUriForFile(this, this.getApplicationContext().getPackageName() + ".provider", mediaFile);
            videoUri = FileProvider.getUriForFile(this, "i.am.ce.by.ncy.provider", mediaFile);
        } else {
            videoUri  = Uri.fromFile(mediaFile);
        }
        intent.putExtra(MediaStore.EXTRA_OUTPUT, videoUri);
        intent.putExtra(MediaStore.EXTRA_VIDEO_QUALITY, 1);
        intent.putExtra(MediaStore.EXTRA_SIZE_LIMIT, 5491520L);//5*1048*1048=5MB
        intent.putExtra(MediaStore.EXTRA_DURATION_LIMIT,45);
        startActivityForResult(intent, VIDEO_CAPTURE);
    }

    public void takeVideoFromGallery(){
        Intent intent = new Intent();
        intent.setType("video/*");
        intent.setAction(Intent.ACTION_GET_CONTENT);
        long maxVideoSize = 5 * 1024 * 1024; // 10 MB
        intent.putExtra(MediaStore.EXTRA_SIZE_LIMIT, maxVideoSize);
        startActivityForResult(Intent.createChooser(intent,"Select Video"),REQUEST_TAKE_GALLERY_VIDEO);

    }

onActivityResult 代码

    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == this.RESULT_OK) {

            switch (requestCode) {
                case VIDEO_CAPTURE:
                        if (resultCode == RESULT_OK) {
                            showVideoImage(data.getData());
// Here I want to know what is the size of my Video File
                        } 
                    break;
                case REQUEST_TAKE_GALLERY_VIDEO:
                    if (resultCode == RESULT_OK) {
                        showVideoGallery(data);
// Here I want to know what is the size of my Video File
                    } 
                    break;
          }

Answer 1

AssetFileDescriptor fileDescriptor = getApplicationContext().getContentResolver().openAssetFileDescriptor(uri , "r");
long fileSize = fileDescriptor.getLength();

Answer 2

1. 检查 AssetFileDescriptor.length
2. 如果未找到，则ParcelFileDescriptor.getStatSize在内部隐式检查AssetFileDescriptor.length
3. 如果没有找到，检查MediaStore/ContentResolverURI是否有content://scheme

应该适用于file://，content://计划。-1L如果找不到则返回：

fun Uri.length(contentResolver: ContentResolver)
        : Long {

    val assetFileDescriptor = try {
        contentResolver.openAssetFileDescriptor(this, "r")
    } catch (e: FileNotFoundException) {
        null
    }
    // uses ParcelFileDescriptor#getStatSize underneath if failed
    val length = assetFileDescriptor?.use { it.length } ?: -1L
    if (length != -1L) {
        return length
    }

    // if "content://" uri scheme, try contentResolver table
    if (scheme.equals(ContentResolver.SCHEME_CONTENT)) {
        return contentResolver.query(this, arrayOf(OpenableColumns.SIZE), null, null, null)
                ?.use { cursor ->
                    // maybe shouldn't trust ContentResolver for size: /sf/ask/3381208071/
                    val sizeIndex = cursor.getColumnIndex(OpenableColumns.SIZE)
                    if (sizeIndex == -1) {
                        return@use -1L
                    }
                    cursor.moveToFirst()
                    return try {
                        cursor.getLong(sizeIndex)
                    } catch (_: Throwable) {
                        -1L
                    }
                } ?: -1L
    } else {
        return -1L
    }
}

Answer 3

java.net.URI juri = new java.net.URI(uri.toString());
File mediaFile = new File(juri.getPath());

AUri不是File。

showVideoImage(data.getData());

ACTION_VIDEO_CAPTURE不返回Uri.

而且，您已经知道该文件在哪里。您在 中创建一个File对象takeVideoFromCamera()并将其用于EXTRA_OUTPUT. 按住该File对象（并将其保存在已保存的实例状态中Bundle），然后使用它来找出生成的视频的大小。