在Android中下载文件

Question

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]);
        }
    }
}

这只是显示我过去半小时0%的进展.

我甚至补充道

<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,甚至互联网在我的手机正常工作.

请帮忙.

谢谢
Sneha

Answer 1

我的猜测是“connection.getContentLength()”在 HTTP 上不可靠并返回 0，因此您可能会遇到被零除的异常。由于您没有记录异常，因此您在 Logcat 中看不到任何内容，也没有任何进展。