Uri文件大小始终为0

uri (android.net.Uri)

我需要在文本视图中显示它的大小。我试着这样做:

这是我从用户库获取文件的地方:

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

        Intent selectIntent = new Intent(Intent.ACTION_GET_CONTENT);
        selectIntent.setType("audio/*");
        startActivityForResult(selectIntent, AUDIO_REQUEST_CODE);

    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == AUDIO_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
            if ((data != null) && (data.getData() != null)) {
                audio = data.getData();
            }
        }
    }

然后我将其传递给下一个活动,如下所示:

Intent debugIntent = new Intent(this, Debug.class);
        Bundle bundle = new Bundle();
        bundle.putString("audio", audio.toString());
        debugIntent.putExtras(bundle);
        startActivity(debugIntent);

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

    Intent intent = this.getIntent();
    Bundle bundle = intent.getExtras();
    audio = Uri.parse((String) bundle.get("audio"));

    File file = new File(audio.getPath());
    long size = file.length();
    if (file.exists()) {
        Toast.makeText(this, "exists", Toast.LENGTH_SHORT).show();
    }
    filesize = (TextView) findViewById(R.id.file_size);
    filesize.setText("file size: ".concat(String.valueOf(size)));

}

file.length()

我怎样才能解决这个问题?