以上程式碼直接copy即可使用!

Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.img_public_no);

public static void saveImageToGallery(Context context, Bitmap bmp) {
        // 首先儲存圖片
        File appDir = new File(Environment.getExternalStorageDirectory(), "Boohee");
        if (!appDir.exists()) {
            appDir.mkdir();
        }
        String fileName = System.currentTimeMillis() + ".jpg";
        File file = new File(appDir, fileName);
        try {
            FileOutputStream fos = new FileOutputStream(file);
            bmp.compress(Bitmap.CompressFormat.JPEG, 100, fos);
            fos.flush();
            fos.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        // 其次把檔案插入到系統圖庫
        try {
            MediaStore.Images.Media.insertImage(context.getContentResolver(),
                                                file.getAbsolutePath(), fileName, null);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        // 最後通知相簿更新
        context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse(file.getAbsolutePath())));

    }