Android中图片的文件储存

public static void saveMyBitmap(Bitmap mBitmap, String fileName) {
        // 新建文件
        File f = new File(fileName);
        // 新建文件输出流
        FileOutputStream fOut = null;
        try {
            fOut = new FileOutputStream(f);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        // 将bitmap压缩至文件输出流
        mBitmap.compress(Bitmap.CompressFormat.JPEG, 100, fOut);
        try {
            fOut.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }
        try {
            fOut.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

public boolean compress(Bitmap.CompressFormat format, int quality, OutputStream stream) {
        throw new RuntimeException("Stub!");
    }

public static enum CompressFormat {
        JPEG,
        PNG,
        WEBP;

        private CompressFormat() {
        }
    }

public class DownloadTask extends AsyncTask<String, Integer , String> {

    Context context;

    public DownloadTask(Context context){
        this.context = context;
    }

    @Override
    protected String doInBackground(String... strings) {
        // 文件的下载地址
        String fileUrl = strings[0];
        // 文件名
        String fileName = strings[1];
        // 文件的扩展名
        String expandName = strings[2];

        try {
            // 下载图片
            URL u = new URL(fileUrl);
            InputStream is = u.openStream();
            DataInputStream dis = new DataInputStream(is);
            // 保存图片文件
            byte[] buffer = new byte[1024];
            int length;
            FileOutputStream fos = new FileOutputStream(new File(fileName + expandName));
            while ((length = dis.read(buffer))>0) {
                fos.write(buffer, 0, length);
            }
            // 扫描指定文件使媒体更新
            Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
            Uri uri = Uri.fromFile(new File(fileName + expandName));
            intent.setData(uri);
            context.sendBroadcast(intent);

        } catch (MalformedURLException mue) {
            mue.printStackTrace();
        } catch (IOException ioe) {
            ioe.printStackTrace();
        } catch (SecurityException se) {
            se.printStackTrace();
        }

        return (fileName+expandName);
    }

    @Override
    protected void onPostExecute(String fileName) {
        UIUtil.toastMessage(context, "下载成功，图片已保存至:" + fileName);

    }