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In my Android project I call Google api for getting a xml to get directions between two points. I have a class named Getdirections.java in which I create an instance of GMapV2Direction.java class. In GMapV2Direction.java, I call the Google api and parse the xml. In devices below android 2.3, its working fine but in android 4, its getting NetworkOnManinThreadException. Here is My GMapV2Direction.java file. 

import java.io.InputStream;
import java.util.ArrayList;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.protocol.BasicHttpContext;
import org.apache.http.protocol.HttpContext;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import com.google.android.gms.maps.model.LatLng;

import android.util.Log;

public class GMapV2Direction {
public final static String MODE_DRIVING = "driving";
public final static String MODE_WALKING = "walking";

public GMapV2Direction() { }

public Document getDocument(LatLng start, LatLng end, String mode) {
    String url = "http://maps.googleapis.com/maps/api/directions/xml?" 
            + "origin=" + start.latitude + "," + start.longitude  
            + "&destination=" + end.latitude + "," + end.longitude 
            + "&sensor=false&units=metric&mode=driving";

    try {
        HttpClient httpClient = new DefaultHttpClient();
        HttpContext localContext = new BasicHttpContext();
        HttpPost httpPost = new HttpPost(url);
        HttpResponse response = httpClient.execute(httpPost, localContext);
        InputStream in = response.getEntity().getContent();
        DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
        Document doc = builder.parse(in);
        return doc;
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}

public String getDurationText (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("duration");
    Node node1 = nl1.item(0);
    NodeList nl2 = node1.getChildNodes();
    Node node2 = nl2.item(getNodeIndex(nl2, "text"));
    Log.i("DurationText", node2.getTextContent());
    return node2.getTextContent();
}

public int getDurationValue (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("duration");
    Node node1 = nl1.item(0);
    NodeList nl2 = node1.getChildNodes();
    Node node2 = nl2.item(getNodeIndex(nl2, "value"));
    Log.i("DurationValue", node2.getTextContent());
    return Integer.parseInt(node2.getTextContent());
}

public String getDistanceText (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("distance");
    Node node1 = nl1.item(0);
    NodeList nl2 = node1.getChildNodes();
    Node node2 = nl2.item(getNodeIndex(nl2, "text"));
    Log.i("DistanceText", node2.getTextContent());
    return node2.getTextContent();
}

public int getDistanceValue (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("distance");
    Node node1 = nl1.item(0);
    NodeList nl2 = node1.getChildNodes();
    Node node2 = nl2.item(getNodeIndex(nl2, "value"));
    Log.i("DistanceValue", node2.getTextContent());
    return Integer.parseInt(node2.getTextContent());
}

public String getStartAddress (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("start_address");
    Node node1 = nl1.item(0);
    Log.i("StartAddress", node1.getTextContent());
    return node1.getTextContent();
}

public String getEndAddress (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("end_address");
    Node node1 = nl1.item(0);
    Log.i("StartAddress", node1.getTextContent());
    return node1.getTextContent();
}

public String getCopyRights (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("copyrights");
    Node node1 = nl1.item(0);
    Log.i("CopyRights", node1.getTextContent());
    return node1.getTextContent();
}

public ArrayList<LatLng> getDirection (Document doc) {
    NodeList nl1, nl2, nl3;
    ArrayList<LatLng> listGeopoints = new ArrayList<LatLng>();
    nl1 = doc.getElementsByTagName("step");
    if (nl1.getLength() > 0) {
        for (int i = 0; i < nl1.getLength(); i++) {
            Node node1 = nl1.item(i);
            nl2 = node1.getChildNodes();

            Node locationNode = nl2.item(getNodeIndex(nl2, "start_location"));
            nl3 = locationNode.getChildNodes();
            Node latNode = nl3.item(getNodeIndex(nl3, "lat"));
            double lat = Double.parseDouble(latNode.getTextContent());
            Node lngNode = nl3.item(getNodeIndex(nl3, "lng"));
            double lng = Double.parseDouble(lngNode.getTextContent());
            listGeopoints.add(new LatLng(lat, lng));

            locationNode = nl2.item(getNodeIndex(nl2, "polyline"));
            nl3 = locationNode.getChildNodes();
            latNode = nl3.item(getNodeIndex(nl3, "points"));
            ArrayList<LatLng> arr = decodePoly(latNode.getTextContent());
            for(int j = 0 ; j < arr.size() ; j++) {
                listGeopoints.add(new LatLng(arr.get(j).latitude,    arr.get(j).longitude));
            }

            locationNode = nl2.item(getNodeIndex(nl2, "end_location"));
            nl3 = locationNode.getChildNodes();
            latNode = nl3.item(getNodeIndex(nl3, "lat"));
            lat = Double.parseDouble(latNode.getTextContent());
            lngNode = nl3.item(getNodeIndex(nl3, "lng"));
            lng = Double.parseDouble(lngNode.getTextContent());
            listGeopoints.add(new LatLng(lat, lng));
        }
    }

    return listGeopoints;
}

private int getNodeIndex(NodeList nl, String nodename) {
    for(int i = 0 ; i < nl.getLength() ; i++) {
        if(nl.item(i).getNodeName().equals(nodename))
            return i;
    }
    return -1;
}

private ArrayList<LatLng> decodePoly(String encoded) {
    ArrayList<LatLng> poly = new ArrayList<LatLng>();
    int index = 0, len = encoded.length();
    int lat = 0, lng = 0;
    while (index < len) {
        int b, shift = 0, result = 0;
        do {
            b = encoded.charAt(index++) - 63;
            result |= (b & 0x1f) << shift;
            shift += 5;
        } while (b >= 0x20);
        int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
        lat += dlat;
        shift = 0;
        result = 0;
        do {
            b = encoded.charAt(index++) - 63;
            result |= (b & 0x1f) << shift;
            shift += 5;
        } while (b >= 0x20);
        int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
        lng += dlng;

        LatLng position = new LatLng((double) lat / 1E5, (double) lng / 1E5);
        poly.add(position);
    }
    return poly;
}

}

This is my Getdirection.java file from where i instantiate GMapV2Direction.java.

public class GetDirectionsActivity extends FragmentActivity {

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.getdirections);
....
....
....
Document doc = md.getDocument(userLocation, toPosition,
            GMapV2Direction.MODE_DRIVING);
    ArrayList<LatLng> directionPoint = md.getDirection(doc);
    PolylineOptions rectLine = new PolylineOptions().width(3).color(
            Color.RED);

    for (int i = 0; i < directionPoint.size(); i++) {
        rectLine.add(directionPoint.get(i));
    }

    map.addPolyline(rectLine);

....
....
....
}
}

Kindly give a suggestion so that I can handle this exception. Any edit in my file is welcome!

4

2 回答 2

0

这是答案。

import java.util.ArrayList;

import org.w3c.dom.Document;

import android.app.Dialog;
import android.content.Intent;
import android.graphics.Color;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationManager;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

 import com.google.android.gms.maps.CameraUpdateFactory;
 import com.google.android.gms.maps.GoogleMap;
 import com.google.android.gms.maps.GoogleMapOptions;
 import com.google.android.gms.maps.SupportMapFragment;
 import com.google.android.gms.maps.model.BitmapDescriptorFactory;
 import com.google.android.gms.maps.model.LatLng;
 import com.google.android.gms.maps.model.MarkerOptions;
import com.google.android.gms.maps.model.PolylineOptions;


public class GetDirectionsActivity extends FragmentActivity {

private String provider;
double lati;
double longi;
String name;
GMapV2Direction md;
GoogleMap map;

Location location;

LatLng userLocation, toPosition;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.getdirections);
    ....
new ParseXML().execute();
    .....

}


private class ParseXML extends AsyncTask<Void, Void, Document> {
    Document doc;
    PolylineOptions rectLine;
    @Override
    protected Document doInBackground(Void... params) {
        doc = md.getDocument(userLocation, toPosition,
                GMapV2Direction.MODE_DRIVING);
        ArrayList<LatLng> directionPoint = md.getDirection(doc);
        rectLine = new PolylineOptions().width(3).color(
                Color.RED);

        for (int i = 0; i < directionPoint.size(); i++) {
            rectLine.add(directionPoint.get(i));
        }
        return null;

    }

    @Override
    protected void onPostExecute(Document result) {
        // TODO Auto-generated method stub
        map.addPolyline(rectLine);
    }

}

}

我没有在主类中创建实例，而是在 asynctask 中创建了用于调用 google api 的实例。休息 Asynctask 做了.... :)

于 2013-03-29T06:40:33.613 回答
0

NetworkOnMainThreadException是当您尝试在主线程上访问 Internet 时引起的。将您访问互联网的代码放入AyncTask.

public class DemoAsyncTask extends AsyncTask<Integer, Void, Void> {

    ProgressDialog progressDialog;
    Context context;

    public DemoAsyncTask(Context context) {
        this.context = context;
    }

    @Override
    protected void onPreExecute() {
        progressDialog = ProgressDialog.show(context, "Title", "Message");
        super.onPreExecute();
    }


    @Override
    protected Void doInBackground(Integer... params) {
        // call your method here
        return null;
    }


    @Override
    protected void onPostExecute(Void result) {
        progressDialog.dismiss();
        super.onPostExecute(result);
    }
}

把它放在一个单独的文件名中DemoAsyncTask.java

于 2013-03-28T09:12:15.173 回答