android - 下载文件时出现 InputStream 异常

Question

我正在尝试从服务器下载 PPT 文件。 它以字节为单位。

但在调试时我注意到输入流在运行时抛出 FileNotFound 异常。该文件确实存在于服务器上，这是我的代码，我们将不胜感激。

public class DownloadFileAsync extends AsyncTask<String, String, String> {


@Override
protected String doInBackground(String... aurl) {
    int count;

    try {
        URL url = new URL(aurl[0]);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.addRequestProperty("Authorization", "Basic " + SharedPref.getAuthPrefValue());
        connection.addRequestProperty("Device", BaseApplication.getCurrentDevice().getDevice().toString());
        connection.addRequestProperty("DeviceId", BaseApplication.getCurrentDevice().getDeviceId());
        connection.connect();

        int lengthOfFile = connection.getContentLength();
        Log.d("ANDRO_ASYNC", "Length of file: " + lengthOfFile);

        InputStream input = new BufferedInputStream(url.openStream());
        File sdcardDest = new File(Environment.getExternalStorageDirectory(), "Availo");
        String finalDest = sdcardDest + File.separator + "Check1" + "." + "PPT";
        OutputStream output = new FileOutputStream(finalDest);

        byte data[] = new byte[1024];

        long total = 0;

        while ((count = input.read(data)) != -1) {
            total += count;
            publishProgress(""+(int)((total*100)/lengthOfFile));
            output.write(data, 0, count);
        }

        output.flush();
        output.close();
        input.close();

    } catch (Exception e) {
        e.printStackTrace();
    }


    return null;
}

我在 Mac 上使用 Charles(类似于 Windows 上的 fiddler)来查看我从服务器发送和接收的内容， 服务器没有返回任何错误，尽管它显示了 6-7 秒的下载步骤，下载了大约 400 字节然后停止。

异常从输入流中抛出。

谢谢!

Answer 1

我建议你看看 DownloadManager系统服务。它专为您要执行的操作而设计:

(来自文档)

The download manager is a system service that handles long-running HTTP downloads. Clients may request that a URI be downloaded to a particular destination file. The download manager will conduct the download in the background, taking care of HTTP interactions and retrying downloads after failures or across connectivity changes and system reboots