Bitmap 写入本地

// 加载图片
        AsyncTask<String, Void, Bitmap> as = new AsyncTask<String, Void, Bitmap>() {
            @Override
            protected Bitmap doInBackground(String... params) {
                try {
                    URL url = new URL(params[0]);
                    HttpURLConnection con = (HttpURLConnection) url
                            .openConnection();
                    if (con.getResponseCode() == 200) {
                        InputStream is = con.getInputStream();
                        Bitmap bitmap=BitmapFactory.decodeStream(is);
                        File file = new File("mnt/sdcard" + bean.imageurl);
                        OutputStream os = new FileOutputStream(file);
                        bitmap.compress(Bitmap.CompressFormat.PNG, 100, os);
                        os.flush();
                        //Bitmap bitmap1 = BitmapFactory.decodeFile("mnt/sdcard"+bean.imageurl);
                        return bitmap;
                    }
                } catch (Exception e) {
                    System.out.println("Exception");
                    e.printStackTrace();
                }
                return null;
            }

            @Override
            protected void onPostExecute(Bitmap result) {
                vh.iamge.setImageBitmap(result);
                super.onPostExecute(result);
            }

        };
        as.execute("http://172.17.29.120/localuser/loupengfei/kaoshi/"
                + bean.imageurl, "gbk");