如何在android中读取特定路径上的文件?

我正在开发一个应用程序,在这个应用程序中,我打开文件浏览器,选择我选择的任何文件并检索其内容。打开的默认路径是/storage/sdcard0。我可以读取直接位于该路径中的任何文件的内容。但是,对于包含在/storage/sdcard0/中的任何文件夹中的任何文件。无法访问。程序给出了一个文件未找到错误。此外,我无法理解这些文件的路径,例如,如果文件位于路径中:

/存储/sdcard0/DCIM/100ANDRO/DSC_0001.jpg

下面是代码段:

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

    Log.d(TAG, "requestCode received: "+requestCode+" result code: "+resultCode);

    if (requestCode == 1 && resultCode == RESULT_OK) {

        Bitmap thumbnail = (Bitmap) data.getExtras().get("data");
        String folderPath = "Anant";
        String filePath = "image.jpg";

        String imagePath = saveToInternalStorage(thumbnail, folderPath,
                sImageName);

        Log.i(TAG, "DeviceAPIS:actual path :: "
                + imagePath.trim().toString());
        sendCameraData(imagePath.toString().trim(),
                ptrAppContainerForCamera);
    }

    else if (requestCode == REQUEST_PATH){
        if (resultCode == RESULT_OK) {
              // Get the Uri of the selected file
            Uri uri = data.getData();
            Log.d(TAG, "data.getData() result line 742: " + uri);
            String uriString = uri.toString();
            File myFile = new File(uriString);
            String path = myFile.getAbsolutePath();
            String base64 ="Error";
            byte[] bytesRead = base64.getBytes();
            String displayName = null;
            String fileName = null;

            if (uriString.startsWith("content://")) {               
                Cursor cursor = null;
                try {                           
                    cursor = mContext.getContentResolver().query(uri, null, null, null, null);                         
                    if (cursor != null && cursor.moveToFirst()) {                               
                        displayName = cursor.getString(cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME));
                        displayName = path + "/" + displayName;
                        Log.d(TAG, "BEFORE REPLACE: "+displayName);
                        int index = displayName.indexOf(':');
                        fileName = displayName.substring(index + 1, displayName.length());
                        Log.d(TAG,"displayName line 762 " + Part);
                    }
                } finally {
                    cursor.close();
                }
            } else if (uriString.startsWith("file://")) {
                Log.d(TAG, "FILE BLOCK LINE 768");           
                displayName = myFile.getName();
                Log.d(TAG,"displayName 11" + displayName);
            }


            try{
                File sdcard = Environment.getExternalStorageDirectory();
                File readFile = new File(sdcard, fileName);
        //      File readFile = new File(uri);

                int length = (int)readFile.length();

                byte[] bytes = new byte[length];

                FileInputStream in = new FileInputStream(readFile);
                try{
                    in.read(bytes);
                }finally {
                    in.close();
                }

                String contents = new String(bytes);
                Log.d(TAG,"contents read :: \\n"  + contents);

                //convert to Base64
                bytesRead = contents.getBytes("UTF-8");
                base64 = Base64.encodeToString(bytesRead,Base64.DEFAULT);

            }catch (Exception e){
                Log.d(TAG, "THROWING EXCEPTION");
                Log.e(TAG,e.getMessage(),e);
            }
        }

引发的异常为 java.io.FileNotFoundException 。非常感谢您的帮助。