android - 无法写入 SD 卡

Question

我的应用程序允许用户拍照，我希望将该照片存储在应用程序的外部文件目录中 (getExternalFilesDir(null))。除了对 renameTo() 的调用外，一切正常，此调用返回 false，我不知道为什么。

源文件是:

/storage/extSdCard/DCIM/Camera/20140424_154458.jpg

目标文件是:

/storage/emulated/0/Android/data/com.myapp.myapp/files/20140424_154458.jpg

我还指定了 WRITE_EXTERNAL_STORAGE 权限。

@Override
public boolean onOptionsItemSelected(MenuItem item)
{
    if (item.getItemId() == R.id.action_take_picture)
    {
        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        startActivityForResult(intent, TAKE_PICTURE_REQUEST_CODE);
        return true;
    }
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
    if (requestCode == TAKE_PICTURE_REQUEST_CODE && resultCode == RESULT_OK)
    {
        File dest = new File(
            getExternalFilesDir(null),
            new SimpleDateFormat("yyyyMMdd_hhmmss", Locale.getDefault()).format(new Date()) + ".jpg");

        File src = new File(convertMediaUriToPath(data.getData()));
        if (src.renameTo(dest)) // Always returns false
        {
            mAdapter.add(dest);
            mAdapter.notifyDataSetChanged();
        }
    }
}

private String convertMediaUriToPath(Uri uri)
{
    String[] proj = {MediaStore.Images.Media.DATA};
    Cursor cursor = getContentResolver().query(uri, proj, null, null, null);
    int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
    cursor.moveToFirst();
    String path = cursor.getString(column_index);
    cursor.close();

    return path;
}

Answer 1

我以前遇到过这个问题 - 不幸的是，您不能使用 renameTo 在不同挂载点(例如，内部和外部存储)之间移动文件和/或目录。考虑使用不同的文件移动方式，例如此处概述的方式:

http://www.mkyong.com/java/how-to-copy-directory-in-java/

public static void copyFolder(File src, File dest) throws IOException{

    if(src.isDirectory()){

        //if directory not exists, create it
        if(!dest.exists()){
           dest.mkdir();
           System.out.println("Directory copied from " 
                          + src + "  to " + dest);
        }

        //list all the directory contents
        String files[] = src.list();

        for (String file : files) {
           //construct the src and dest file structure
           File srcFile = new File(src, file);
           File destFile = new File(dest, file);
           //recursive copy
           copyFolder(srcFile,destFile);
        }

    }else{
        //if file, then copy it
        //Use bytes stream to support all file types
        InputStream in = new FileInputStream(src);
            OutputStream out = new FileOutputStream(dest); 

            byte[] buffer = new byte[1024];

            int length;
            //copy the file content in bytes 
            while ((length = in.read(buffer)) > 0){
               out.write(buffer, 0, length);
            }

            in.close();
            out.close();
            System.out.println("File copied from " + src + " to " + dest);
    }
}