java - Android - Spinner 异步下载无法正常运行

Question

激活微调器中的任何按钮后，都会出现进度对话框，但没有任何反应。我让这个与按钮完美配合，但不明白转换到旋转器时这里出了什么问题。有人发现下载无法正常启动的原因吗？

public class SpinnerActivity extends Activity {

public static final int DIALOG_DOWNLOAD_PROGRESS = 0;
private ProgressDialog mProgressDialog;

Spinner spDownloadFrom;
private ArrayAdapter<CharSequence> spinnerArrayAdapter;
String url[] = {"http://www.becker.cl/bases.pdf",
        "http://www.pitt.edu/documents/campusmap0607.pdf", "http://www.aara.ca/reg3317/web_page_doc.pdf",
        "www.dataprotection.ie/documents/guidance/GuidanceFinance.pdf", "http://www.fmbb2012.com/JumpingQualifica1.pdf",
        "http://www.consulatdumaroc.ca/coloniefh22012.pdf", "http://www.rgrdlaw.com/media/cases/140_Complaint.pdf" };
String name[] = { "bases.pdf", "campusmap0607.pdf", "web_page_doc.pdf", "GuidanceFinance.pdf",
        "JumpingQualifica1.pdf", "coloniefh22012.pdf", "140_Complaint.pdf", };

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    mProgressDialog = new ProgressDialog(SpinnerActivity.this);
    mProgressDialog.setMessage("Please be patient, file downloading...");
    mProgressDialog.setIndeterminate(false);
    mProgressDialog.setMax(100);
    mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);

    spDownloadFrom = (Spinner) findViewById(R.id.Spinner01);

    spinnerArrayAdapter = new ArrayAdapter<CharSequence>(this,
            android.R.layout.simple_spinner_item, name);
    spinnerArrayAdapter
            .setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spDownloadFrom.setAdapter(spinnerArrayAdapter);

    spDownloadFrom.setOnItemSelectedListener(new SpinnerListener(
            spDownloadFrom));
}

public class SpinnerListener implements OnItemSelectedListener {
    Spinner sp;

    public SpinnerListener(View v) {
        sp = (Spinner) findViewById(v.getId());
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View v, int arg2,
            long arg3) {
        // Call to download class
        startDownload(arg2);


    }

    @Override
    public void onNothingSelected(AdapterView<?> arg0) {
        // TODO Auto-generated method stub

    }
}

private void startDownload(Integer... url) {
    DownloadFile downloadFile = new DownloadFile();
    downloadFile.execute();

}

class DownloadFile extends AsyncTask<String, Integer, String> { // put your
                                                                // download
                                                                // code

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

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

    @Override
    protected String doInBackground(String... aurl) {
        try {

            URL url = new URL(aurl[0]);
            URLConnection connection = url.openConnection();

            connection.connect();
            int fileLength = connection.getContentLength();
            int tickSize = 2 * fileLength / 100;
            int nextProgress = tickSize;

            Log.d(

            "ANDRO_ASYNC", "Lenght of file: " + fileLength);

            InputStream input = new BufferedInputStream(url.openStream());

            String path = Environment.getExternalStorageDirectory()
                    + "/Android/Data/"
                    + getApplicationContext().getPackageName() + "/files/" + name;
            File file = new File(path);
            file.mkdirs();
            File outputFile = file;

            OutputStream output = new FileOutputStream(outputFile);

            byte data[] = new byte[1024 * 1024];
            long total = 0;
            int count;
            while ((count = input.read(data)) != -1) {
                total += count;
                if (total >= nextProgress) {
                    nextProgress = (int) ((total / tickSize + 1) * tickSize);
                    this.publishProgress((int) (total * 100 / fileLength));
                }
                output.write(data, 0, count);
            }

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

        } catch (Exception e) {
        }
        return null;
    }

    protected void onProgressUpdate(String... progress) {
        Log.d("Downloading", progress[0]);

    }

    @Override
    protected void onPostExecute(String unused) {

        File file = new File(Environment.getExternalStorageDirectory()
                + "/Android/Data/"
                + getApplicationContext().getPackageName()
                + "/files/" + name);
        Intent testIntent = new Intent(Intent.ACTION_VIEW);
        testIntent.setType("application/pdf");
        Intent intent = new Intent();
        intent.setAction(Intent.ACTION_VIEW);
        Uri uri = Uri.fromFile(file);
        intent.setDataAndType(uri, "application/pdf");
        try {
            startActivity(intent);
        } catch (ActivityNotFoundException e) {
            Toast.makeText(SpinnerActivity.this,
                    "No Application Available to View PDF",
                    Toast.LENGTH_LONG).show();
        }
    }
}
}

Answer 1

在 startDownload 方法中，您传入 url，它是一个 String 类型的数组。在 AsyncTask 的 doInBackground 中，您仅使用 url 的第一个索引，您已将其设置为 ""，因此您传递的是一个空的String。

要传入您期望的 URL，请将 startDownload 方法更改为接受 int 值。然后在 onItemSelected 方法中，传入您命名为 arg2 的位置(参数名称应按顺序为parent、view、position 和 id。更容易理解它们的意思)。然后当你调用downloadFile.execute时，传入url[position]。

编辑

将您的下载方法更改为如下所示:

private void startDownload(int position) {
    DownloadFile downloadFile = new DownloadFile();
    downloadFile.execute(url[position]);
}

假设您使用的 URL 有效，这应该会给您预期的结果。此外，您的对话框不会消失，因为您忘记在 onPostExecute 中调用 mProgressDialog.dismiss()。