android - 在Android中下载文件

我使用以下代码在Android中下载文件：

public class FileDownloadActivity extends Activity {
    ProgressDialog mProgressDialog;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        mProgressDialog = new ProgressDialog(FileDownloadActivity.this);
        mProgressDialog.setMessage("Downlaoding File...");
        mProgressDialog.setIndeterminate(false);
        mProgressDialog.setMax(100);
        mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);

        // execute this when the downloader must be fired
        DownloadFile downloadFile = new DownloadFile();
        downloadFile.execute("http://code.google.com/android/goodies/wallpaper/android-wallpaper5_1024x768.jpg");
    }

    private class DownloadFile extends AsyncTask<String, Integer, String> {
        @Override
        protected String doInBackground(String... sUrl) {
            try {
                Log.i("","In doin bggggggggggggg");
                URL url = new URL(sUrl[0]);
                URLConnection connection = url.openConnection();
                connection.connect();

                // this will be useful so that you can show a typical 0-100% progress bar
                int fileLength = connection.getContentLength();
                // download the file
                InputStream input = new BufferedInputStream(url.openStream());
                OutputStream output = new FileOutputStream("/sdcard/sample.jpg");
                byte data[] = new byte[1024];
                long total = 0;
                int count;
                while ((count = input.read(data)) != -1) {
                    total += count;
                    // publishing the progress....
                    publishProgress((int) (total * 100 / fileLength));
                    output.write(data, 0, count);
                }
                output.flush();
                output.close();
                input.close();
            } catch (Exception e) {

            }
            return null;
        }

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            mProgressDialog.show();
        }

        @Override
        protected void onProgressUpdate(Integer... progress) {
            super.onProgressUpdate(progress);
            mProgressDialog.setProgress(progress[0]);
        }
    }
}

这只是显示了我过去半个小时0%的进展。
我甚至还加了一句

<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission>
<uses-permission android:name="android.permission.READ_PHONE_STATE"></uses-permission>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>

在清单中
我的手机连上网都很好用。
请帮忙。
谢谢
斯尼哈

最佳答案

我的猜测是“connection.getContentLength（）”在http上不可靠，返回0，所以可能得到了一个被零除的异常。因为你没有记录异常，所以在logcat中看不到任何东西，也看不到任何进展。