android - 将水平进度条添加到AsyncTask

Question

我正在尝试创建一个应用程序，它将从网址下载网页的源代码并在 TextView 中显示。我还希望它显示水平进度条< / strong>在后台下载页面时。我已成功使用 Asynctask 在后台下载网页，但我不知道如何找出网页的大小并根据后台的下载状态更新进度条

这就是我正在下载的网页源代码 -

package com.example.gc;

import java.io.IOException;

import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.impl.client.DefaultHttpClient;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {
private TextView tv;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    tv = (TextView) findViewById(R.id.cd);
    grabURL("http://google.com");
}

public void grabURL(String url) {
    new GrabURL().execute(url);
}

private class GrabURL extends AsyncTask<String, Void, Void> {
    private final HttpClient Client = new DefaultHttpClient();
    private String Content;
    private String Error = null;

    protected Void doInBackground(String... urls) {
        try {
            HttpGet httpget = new HttpGet(urls[0]);
            ResponseHandler<String> responseHandler = new BasicResponseHandler();
            Content = Client.execute(httpget, responseHandler);

        } catch (ClientProtocolException e) {
            Error = e.getMessage();
            cancel(true);
        } catch (IOException e) {
            Error = e.getMessage();
            cancel(true);
        }

        return null;
    }

    protected void onPostExecute(Void unused) {
        if (Error != null) {
            Toast.makeText(MainActivity.this, Error, Toast.LENGTH_LONG).show();
        } else {
          //  Toast.makeText(MainActivity.this, "Source: " + Content, Toast.LENGTH_LONG).show();
            tv.setText(Content);
        }
    }

}
}

请帮助我在我的应用中显示和更新水平进度条。提前谢谢！

Answer 1

您只想在AsyncTask onPreExecute（）中创建进度对话框。如下所示：

ProgressDialog mProgressDialog;
class DownloadFileAsync extends AsyncTask<String, String, String> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        mProgressDialog = new ProgressDialog(getParent());
            mProgressDialog.setTitle("Please wait");
            mProgressDialog.setMessage("Downloading ...");
            mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            mProgressDialog.setCancelable(false);
            mProgressDialog.show();

    }

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

    try {

            URL url = new URL(aurl[0]);
            URLConnection conexion = url.openConnection();
            conexion.connect();
             //Downloading progress update
             //your downloding logic over here

              /* int lenghtOfFile= urlConnection.getContentLength();
              InputStream input = new BufferedInputStream(url.openStream());
                OutputStream output = newFileOutputStream(outputFile);

                byte data[] = new byte[1024];

                long total = 0;
                    while ((count = input.read(data)) != -1) {
                        total += count;
                        publishProgress(""+(int)((total*100)/lenghtOfFile));*/

                    }

    } catch (Exception e) {}
    return null;

    }
    @Override
    protected void onProgressUpdate(String... progress) {
         Log.d("ANDRO_ASYNC",progress[0]);
                      //Update Progress
         mProgressDialog.setProgress(Integer.parseInt(progress[0]));
    }

    @Override
    protected void onPostExecute(String unused) {

        mProgressDialog.dismiss();

    }
}

在这里，我将向您展示如何将水平进度对话框实现为AsyncTask.Now，并按您自己的方式进行自定义。

Answer 2

this应该回答你的问题。只需发出HTTP请求即可获得网页的大小。

至于在progressBar上显示进度，请查看this

Answer 3

private class GrabURL extends AsyncTask<String, Void, Void> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        // Showing progress dialog
        pDialog = new ProgressDialog(MainActivity.this);
        pDialog.setMessage("Please wait...");
        pDialog.setCancelable(false);
        pDialog.show();

    }

    @Override
    protected Void doInBackground(String... arg0) {
        // download page
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        // Dismiss the progress dialog
        if (pDialog.isShowing())
            pDialog.dismiss();
    }

}