Android-无法让AsyncTask下载多个文件

Question

正如tle所述，我需要使用AsyncTask下载两个文件。当我尝试时，没有下载任何内容。如果需要，我可以给一个logcat。我不确定为什么它不会下载文件。这是我的代码：

package com.cydeon.smirkit;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.concurrent.TimeoutException;

import com.stericson.RootTools.*;
import com.stericson.RootTools.exceptions.RootDeniedException;
import com.stericson.RootTools.execution.CommandCapture;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class Stock extends Activity implements OnClickListener {

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

private String urlPath = "https://dl.dropbox.com/s/";    
private String[] fileNames = {"u-boot_stock.bin","u-boot_stock.md5"};  


/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.stock);
    Button bInstallS = (Button) findViewById(R.id.bInstallS);
    Button bSkipS = (Button) findViewById(R.id.bSkipS);
    bInstallS.setOnClickListener(this);
    bSkipS.setOnClickListener(this);
    mProgressDialog = new ProgressDialog(Stock.this);
    mProgressDialog.setMessage("Downloading..." );
    mProgressDialog.setIndeterminate(false);
    mProgressDialog.setMax(100);
    mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
}
        public void onClick(View arg0) {
            switch(arg0.getId()){
                case R.id.bInstallS:
                    AlertDialog.Builder builder = new AlertDialog.Builder(Stock.this);
                    builder.setPositiveButton(R.string.continueStock, new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            startDownload();
                        }
                        });
                    builder.setNegativeButton(R.string.cancelStock, new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            Stock.this.finish();
                        }
                        });
                    builder.setMessage(R.string.messageStock);
                    builder.setTitle(R.string.titleStock);
                    AlertDialog dialog = builder.create();
                    dialog.show();



                    break;
                case R.id.bSkipS:
                    Intent skip = new Intent(Stock.this, Twrp.class);
                    startActivity(skip);

        }
        }

private void startDownload() {      

    if(checkExternalMedia()==true) {

           File file = null;                
           for(int i=0; i<fileNames.length; i++) {
                file = new File(Environment.getExternalStorageDirectory()+fileNames[i]);
                boolean exists = file.exists();
                if(exists){
                    continue;
                }
                else {
                    new DownloadFileAsync().execute(urlPath+"2mtbqt7mk5khqu3/"+fileNames[i],"klw4vb0valwds2p/"+fileNames[i]);               
                }
                file = null;
            }               
        }            
    else {          
    }
}
/** Method to check whether external media available and writable. */

private boolean checkExternalMedia(){
    boolean mExternalStorageAvailable = false;
    boolean mExternalStorageWriteable = false;
    boolean stat;
    String state = Environment.getExternalStorageState();

    if (Environment.MEDIA_MOUNTED.equals(state)) {
        // Can read and write the media
        mExternalStorageAvailable = mExternalStorageWriteable = true;
        stat = true;
    } else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
        // Can only read the media
        mExternalStorageAvailable = true;
        mExternalStorageWriteable = false;
        stat = false;
    } else {
        // Can't read or write
        mExternalStorageAvailable = mExternalStorageWriteable = false;
        stat = false;
    }

    return stat;
}

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

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

    protected String doInBackground(String... sURL) {
        try{
            URL url = new URL(sURL[0]);
            URLConnection connection = url.openConnection();
            connection.connect();
            //Shows 0-100% progress bar
            int fileLength = connection.getContentLength();

            //Download the file
            InputStream input = new BufferedInputStream(url.openStream());
            OutputStream output = new FileOutputStream("/sdcard/"+fileNames);

            byte data[] = new byte[1024];
            long total = 0;
            int count;
            while ((count = input.read(data)) != -1) {
                total += count;
                //Publish 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 onPostExecute(String unused) {
        mProgressDialog.dismiss();
        Context context = getApplicationContext();
        CharSequence text = "Installing. Please Wait";
        int duration = Toast.LENGTH_SHORT;
        Toast toast = Toast.makeText(context, text, duration);
        toast.show();
        RootTools.remount("/system", "rw");
        CommandCapture command = new CommandCapture(0, "su");
        try {
            RootTools.getShell(true).add(command).waitForFinish();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (TimeoutException e) {
            e.printStackTrace();
        } catch (RootDeniedException e) {
            e.printStackTrace();
        }
    }
}


}

所以，再次，如果需要，我可以提供logcat。这是我第一次尝试这个，所以我不确定我在做什么..

Answer 1

如果我理解正确，您不希望同时（同时）下载所有文件，而是逐个（连续）下载。为此，使用要下载的URL构建一个String数组，并使用该数组调用execute（）。