Fortschrittsbalken für AsyncTask Herunterladen

Question

Ich will nur eine App machen nacheinander mehrere Dateien zum Download bereit. Aber wenn ich Download-Button klicken, wird der Fortschrittsbalken nicht mehr bewegen und logcat zeigt:

05-11 18:46:26.227 2653-2899/shiweichen22gmail.q4 E/Error: /storage/emulated/0/Q4.txt: open failed: EACCES (Permission denied) 

Ich habe bereits die Erlaubnis im manifest.xml

mainactivity.XML

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:app="http://schemas.android.com/apk/res-auto" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
android:paddingBottom="@dimen/activity_vertical_margin" 
android:paddingLeft="@dimen/activity_horizontal_margin" 
android:paddingRight="@dimen/activity_horizontal_margin" 
android:paddingTop="@dimen/activity_vertical_margin" 
app:layout_behavior="@string/appbar_scrolling_view_behavior" 
tools:context="shiweichen22gmail.q4.MainActivity" 
tools:showIn="@layout/activity_main" 
android:weightSum="1"> 


<TextView 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:textAppearance="?android:attr/textAppearanceLarge" 
    android:text="Large Text" 
    android:id="@+id/textView" 
    android:layout_alignParentTop="true" 
    android:layout_centerHorizontal="true" 
    android:layout_weight="0.17" /> 

<Button 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="Download" 
    android:id="@+id/button" 
    android:layout_below="@+id/textView" 
    android:layout_centerHorizontal="true" 
    android:layout_marginTop="61dp" 
    android:layout_gravity="center_vertical" /> 
</LinearLayout> 

Mainactivity. java

package shiweichen22gmail.q4; 

import android.app.Dialog; 
import android.app.ProgressDialog; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.os.Environment; 
import android.support.design.widget.FloatingActionButton; 
import android.support.design.widget.Snackbar; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v7.widget.Toolbar; 
import android.util.Log; 
import android.view.View; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.widget.Button; 
import android.widget.TextView; 
import java.io.BufferedInputStream; 
import java.io.FileOutputStream; 
import java.io.InputStream; 
import java.io.OutputStream; 
import java.net.URL; 
import java.net.URLConnection; 


public class MainActivity extends AppCompatActivity { 

private Button startBtn; 
private ProgressDialog mProgressDialog; 
String[] URL = {"https://www.dropbox.com/s/gjq0ivomwti4vmw/1.txt?dl=0", 
     }; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    startBtn = (Button)findViewById(R.id.button); 
    startBtn.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      new DownloadFile().execute(URL); 
     } 
    }); 
} 
private class DownloadFile extends AsyncTask<String, Integer, String> { 
    @Override 
    protected void onPreExecute() { 
     super.onPreExecute(); 
     // Create progress dialog 
     mProgressDialog = new ProgressDialog(MainActivity.this); 
     // Set your progress dialog Title 
     mProgressDialog.setTitle("Downloading"); 
     // Set your progress dialog Message 
     mProgressDialog.setMessage("Downloading, Please Wait!"); 
     mProgressDialog.setIndeterminate(false); 
     mProgressDialog.setMax(100); 
     mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); 
     // Show progress dialog 
     mProgressDialog.show(); 
    } 
    @Override 
    protected String doInBackground(String... Url) { 
     try { 
      URL url = new URL(Url[0]); 
      URLConnection connection = url.openConnection(); 
      connection.connect(); 
      // Detect the file lenghth 
      int fileLength = connection.getContentLength(); 
      // Locate storage location 
      String filepath = Environment.getExternalStorageDirectory() 
        .getPath(); 
      // Download the file 
      InputStream input = new BufferedInputStream(url.openStream()); 
      // Save the downloaded file 
      OutputStream output = new FileOutputStream(filepath+ "/" 
        + "Q4.txt"); 
      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) { 
      // Error Log 
      Log.e("Error", e.getMessage()); 
      e.printStackTrace(); 
     } 
     return null; 
    } 
    @Override 
    protected void onProgressUpdate(Integer... progress) { 
     super.onProgressUpdate(progress); 
     // Update the progress dialog 
     mProgressDialog.setProgress(progress[0]); 
     // Dismiss the progress dialog 
     //mProgressDialog.dismiss(); 
    } 
} 
} 

Mainfest.xml

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
package="shiweichen22gmail.q4"> 
<uses-permission android:name="android.permission.INTERNET"/> 
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"> 
</uses-permission> 

<application 
    android:allowBackup="true" 
    android:icon="@mipmap/ic_launcher" 
    android:label="@string/app_name" 
    android:supportsRtl="true" 
    android:theme="@style/AppTheme"> 
    <activity 
     android:name=".MainActivity" 
     android:label="@string/app_name" 
     android:theme="@style/AppTheme.NoActionBar"> 
     <intent-filter> 
      <action android:name="android.intent.action.MAIN" /> 

      <category android:name="android.intent.category.LAUNCHER" /> 
     </intent-filter> 
    </activity> 
</application> 

</manifest> 

Answer 1

Wenn Sie Ihre App auf Marshmallow ausführen, müssen Sie nach Laufzeitberechtigungen fragen. Hier finden Sie weitere Informationen zu Laufzeitberechtigungen http://developer.android.com/training/permissions/requesting.html

Answer 2

Überschreiben Sie die onPostExecute() und setzen Sie mProgressDialog.dismiss(); wie unten:

private class DownloadFile extends AsyncTask<String, Integer, String> { 
@Override 
protected void onPreExecute() { 
    super.onPreExecute(); 
    // Create progress dialog 
    mProgressDialog = new ProgressDialog(MainActivity.this); 
    // Set your progress dialog Title 
    mProgressDialog.setTitle("Downloading"); 
    // Set your progress dialog Message 
    mProgressDialog.setMessage("Downloading, Please Wait!"); 
    mProgressDialog.setIndeterminate(false); 
    mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); 
    // Show progress dialog 
    mProgressDialog.show(); 
} 
@Override 
protected String doInBackground(String... Url) { 
    try { 
     URL url = new URL(Url[0]); 
     URLConnection connection = url.openConnection(); 
     connection.connect(); 
     // Detect the file lenghth 
     int fileLength = connection.getContentLength(); 
     // Locate storage location 
     String filepath = Environment.getExternalStorageDirectory() 
       .getPath(); 
     // Download the file 
     InputStream input = new BufferedInputStream(url.openStream()); 
     // Save the downloaded file 
     OutputStream output = new FileOutputStream(filepath+ "/" 
       + "Q4.txt"); 
     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) { 
     // Error Log 
     Log.e("Error", e.getMessage()); 
     e.printStackTrace(); 
    } 
    return null; 
} 
@Override 
protected void onPostExecute(Void args) { 


     // Close the progressdialog 
     mProgressDialog.dismiss(); 
    }