Wurde versucht, eine Anwendung zum Herunterladen einer Datei auf die SD-Karte zu erstellen. Hier ist mein Cod

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        new Thread(new Runnable() {
            public void run() {

                                Log.i("step0","it starts here");
                URLConnection urlConnection = null;
                // TODO Auto-generated method stub
                try {
                    //fetching the URL
                    Log.i("step 1.1","getting the url");
                    URL url = new URL("http://people.opera.com/howcome/2005/ala/sample.pdf");
                    Log.i("step 1.2","captured the url");                
                    urlConnection = url.openConnection();
                    Log.i("step 1.3","captured the url");    

                    urlConnection.connect();
                    Log.i("step 1","fetching the URL");

                    //specifying path and file name 
                    File sdcard = Environment.getExternalStorageDirectory();
                    File file = new File(sdcard, "filename.pdf");
                    Log.i("step 2","specifying path and file name");

                    //Preparing for download
                    FileOutputStream fileOutput = new FileOutputStream(file);
                    InputStream inputStream = urlConnection.getInputStream();

                    byte[] buffer = new byte[1024];
                    int bufferLength = 0;
                    Log.i("step 3","Preparing for download");


                    //Downloading 
                    while ( (bufferLength = inputStream.read(buffer)) > 0 ) {
                        fileOutput.write(buffer, 0, bufferLength);
                    }
                    fileOutput.close();
                    Log.i("step 4","Downloading");

                } catch (MalformedURLException e) {
                        e.printStackTrace();
                } catch (IOException e) {
                        e.printStackTrace();
                }     
            }
          }).start();


    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

Berechtigungen in der Manifest-Datei:

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_SYNC_SETTINGS"/>
<uses-permission android:name="android.permission.INTERNET"/>

Meine Protokolldatei:

09-11 16:27:27.835: D/jdwp(5892): sendBufferedRequest : len=0x47
09-11 16:27:27.865: W/asset(5892): AssetManager-->addDefaultAssets CIP path not exsit!
09-11 16:27:27.920: V/PhoneWindow(5892): DecorView setVisiblity: visibility = 4
09-11 16:27:27.921: I/step0(5892): it starts here
09-11 16:27:27.922: I/step 1.1(5892): getting the url
09-11 16:27:27.923: I/step 1.2(5892): captured the url
09-11 16:27:27.924: I/step 1.3(5892): captured the url
09-11 16:27:27.935: D/libc-netbsd(5892): getaddrinfo: people.opera.com NO result from proxy 
09-11 16:27:27.937: I/System.out(5892): [CDS][DNS]Unable to resolve host "people.opera.com": No address associated with hostname
09-11 16:27:27.937: W/System.err(5892): java.net.UnknownHostException: Unable to resolve host "people.opera.com": No address associated with hostname
09-11 16:27:27.938: W/System.err(5892):     at java.net.InetAddress.lookupHostByName(InetAddress.java:439)
09-11 16:27:27.938: W/System.err(5892):     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
09-11 16:27:27.938: W/System.err(5892):     at java.net.InetAddress.getAllByName(InetAddress.java:214)
09-11 16:27:27.938: W/System.err(5892):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:70)
09-11 16:27:27.939: W/System.err(5892):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
09-11 16:27:27.939: W/System.err(5892):     at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:340)
09-11 16:27:27.939: W/System.err(5892):     at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:87)
09-11 16:27:27.939: W/System.err(5892):     at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
09-11 16:27:27.939: W/System.err(5892):     at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:316)
09-11 16:27:27.939: W/System.err(5892):     at libcore.net.http.HttpEngine.connect(HttpEngine.java:311)
09-11 16:27:27.939: W/System.err(5892):     at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:290)
09-11 16:27:27.939: W/System.err(5892):     at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:240)
09-11 16:27:27.939: W/System.err(5892):     at libcore.net.http.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:81)
09-11 16:27:27.940: W/System.err(5892):     at com.android.installapp.MainActivity$1.run(MainActivity.java:53)
09-11 16:27:27.940: W/System.err(5892):     at java.lang.Thread.run(Thread.java:838)
09-11 16:27:27.940: W/System.err(5892): Caused by: libcore.io.GaiException: getaddrinfo failed: EAI_NODATA (No address associated with hostname)
09-11 16:27:27.941: W/System.err(5892):     at libcore.io.Posix.getaddrinfo(Native Method)
09-11 16:27:27.941: W/System.err(5892):     at libcore.io.ForwardingOs.getaddrinfo(ForwardingOs.java:59)
09-11 16:27:27.941: W/System.err(5892):     at java.net.InetAddress.lookupHostByName(InetAddress.java:405)
09-11 16:27:27.941: W/System.err(5892):     ... 14 more
09-11 16:27:27.941: W/System.err(5892): Caused by: libcore.io.ErrnoException: getaddrinfo failed: ENETUNREACH (Network is unreachable)
09-11 16:27:27.942: W/System.err(5892):     ... 17 more
09-11 16:27:27.960: V/PhoneWindow(5892): DecorView setVisiblity: visibility = 0
09-11 16:27:28.064: D/libEGL(5892): loaded /system/lib/egl/libEGL_mali.so
09-11 16:27:28.072: D/libEGL(5892): loaded /system/lib/egl/libGLESv1_CM_mali.so
09-11 16:27:28.079: D/libEGL(5892): loaded /system/lib/egl/libGLESv2_mali.so
09-11 16:27:28.183: D/OpenGLRenderer(5892): Enabling debug mode 0
09-11 16:27:28.186: V/InputMethodManager(5892): onWindowFocus: null softInputMode=32 first=true flags=#1810100
09-11 16:27:28.187: V/InputMethodManager(5892): START INPUT: com.android.internal.policy.impl.PhoneWindow$DecorView{413fb9c0 V.E..... R.....ID 0,0-480,854} ic=null tba=android.view.inputmethod.EditorInfo@4141e938 controlFlags=#104
09-11 16:27:28.282: V/InputMethodManager(5892): Starting input: Bind result=InputBindResult{null com.android.inputmethod.latin/.LatinIME #47}
09-11 16:27:28.286: V/InputMethodManager(5892): onWindowFocus: null softInputMode=32 first=false flags=#1810100
09-11 16:27:28.290: V/PhoneWindow(5892): DecorView setVisiblity: visibility = 0
09-11 16:27:28.401: W/IInputConnectionWrapper(5892): showStatusIcon on inactive InputConnection

Ich habe versucht, im Internet zu suchen, kann das Problem jedoch nicht beheben. Die Datei wird nicht heruntergeladen. Kann mir jemand bitte helfen?