Android JSON get data from PHP

Question

Does anyone have any idea what I am doing wrong? I tried doing just about every example out there. I just want to get the lat and lon coords from the server using php to my android phone.

Thank you for your help in advanced

This is the Section of my code which I am having problems with:

public void connect()
{
    StrictMode.ThreadPolicy policy = new   
    StrictMode.ThreadPolicy.Builder().permitAll().build();
    StrictMode.setThreadPolicy(policy);

    HttpClient httpclient = new DefaultHttpClient();

    // Prepare a request object
    HttpGet httpget = new HttpGet("SERVER URL"); 

    // Execute the request
    HttpResponse response;
    try {
        response = httpclient.execute(httpget);
        // Examine the response status
        //Log.i("Info",response.getStatusLine().toString());  Comes back with HTTP/1.1 200 OK

        // Get hold of the response entity
        HttpEntity entity = response.getEntity();

        if (entity != null) {
            InputStream instream = entity.getContent();
            String result= convertStreamToString(instream);

            JSONArray arr = new JSONArray(result);
            JSONObject jObj = arr.getJSONObject(0);
            String lat = jObj.getString("Lat");
            Log.d("OutPut", jObj.getString("Lon"));
            Toast.makeText(this, lat, Toast.LENGTH_LONG).show();
            instream.close();
        }


    } catch (Exception e) {
        Log.e("Error",e.toString());
    }
}

I cannot get the data out of the JSONObject. I keep getting this exception.

03-31 17:23:41.457: E/Error(317): org.json.JSONException: Value <!DOCTYPE of type java.lang.String cannot be converted to JSONArray

The PHP code from my server is outputting:

[{"Lat":"47.9255072","Lon":"-97.0846979","id":"34"}]

Here is all the code in my MainActivity

package com.misterbusllc.misterbusllc;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;

import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;

import org.json.JSONArray;
import org.json.JSONObject;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
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 android.os.Bundle;
import android.os.StrictMode;
import android.content.Intent;
import android.support.v4.app.FragmentActivity;
import android.util.Log;
import android.view.Menu;
import android.widget.SlidingDrawer;
import android.widget.SlidingDrawer.OnDrawerCloseListener;
import android.widget.SlidingDrawer.OnDrawerOpenListener;
import android.widget.Toast;


public class MainActivity extends FragmentActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    connect();

    //contactServer();


    final SlidingDrawer slidingDrawerCost = (SlidingDrawer) findViewById(R.id.slidingDrawerCost);
    final SlidingDrawer slidingDrawerInfo = (SlidingDrawer) findViewById(R.id.slidingDrawerInfo);

    GoogleMap map = ((SupportMapFragment)  getSupportFragmentManager().findFragmentById(R.id.map)).getMap();

    LatLng latLng = new LatLng(47.922612,-97.060776);
    map.setMapType(GoogleMap.MAP_TYPE_NORMAL);
    map.addMarker(new MarkerOptions().position(latLng).title("MisterBus").snippet("MisterBus is currently here").icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE)));
    map.getUiSettings().setCompassEnabled(true);
    map.getUiSettings().setZoomControlsEnabled(true);
    map.animateCamera(CameraUpdateFactory.newLatLngZoom(latLng, 10));

    slidingDrawerCost.setOnDrawerOpenListener(new OnDrawerOpenListener() {
        @Override
        public void onDrawerOpened() {
            Intent intent = new Intent(getApplicationContext(), Cost.class);
            startActivity(intent);
        }
        });
        slidingDrawerCost.setOnDrawerCloseListener(new OnDrawerCloseListener() {

        @Override
        public void onDrawerClosed() {
            slidingDrawerCost.close();
        }
        }); 

        slidingDrawerInfo.setOnDrawerOpenListener(new OnDrawerOpenListener() {
            @Override
            public void onDrawerOpened() {
                Intent intent = new Intent(getApplicationContext(), info.class);
                startActivity(intent);
            }
            });
            slidingDrawerInfo.setOnDrawerCloseListener(new OnDrawerCloseListener() {

            @Override
            public void onDrawerClosed() {
                slidingDrawerInfo.close();
            }
            }); 


}

@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;
}




public void connect()
{
    StrictMode.ThreadPolicy policy = new   
    StrictMode.ThreadPolicy.Builder().permitAll().build();
    StrictMode.setThreadPolicy(policy);

    HttpClient httpclient = new DefaultHttpClient();

    // Prepare a request object
    HttpGet httpget = new HttpGet("SERVER URL"); 

    // Execute the request
    HttpResponse response;
    try {
        response = httpclient.execute(httpget);
        // Examine the response status
        //Log.i("Info",response.getStatusLine().toString());  Comes back with HTTP/1.1 200 OK

        // Get hold of the response entity
        HttpEntity entity = response.getEntity();

        if (entity != null) {
            InputStream instream = entity.getContent();
            String result= convertStreamToString(instream);

            JSONArray arr = new JSONArray(result);
            JSONObject jObj = arr.getJSONObject(0);
            String lat = jObj.getString("Lat");
            Log.d("OutPut", jObj.getString("Lon"));
            Toast.makeText(this, lat, Toast.LENGTH_LONG).show();
            instream.close();
        }


    } catch (Exception e) {
        Log.e("Error",e.toString());
    }
}

    private static String convertStreamToString(InputStream is) {
    /*
     * To convert the InputStream to String we use the BufferedReader.readLine()
     * method. We iterate until the BufferedReader return null which means
     * there's no more data to read. Each line will appended to a StringBuilder
     * and returned as String.
     */
    BufferedReader reader = new BufferedReader(new InputStreamReader(is));
    StringBuilder sb = new StringBuilder();

    String line = null;
    try {
        while ((line = reader.readLine()) != null) {
            sb.append(line + "\n");
        }
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            is.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return sb.toString();
}

}//end of class

PHP CODE:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"     "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset=utf-8" http-equiv="Content-Type" content="application/json"; />
<title>Gps Send</title>
</head>
<body>

<?php
header('Content-type: application/json');
mysql_connect("localhost", "root","password"); 
mysql_select_db("misterbus");
$last =mysql_query("SELECT * FROM location WHERE ID = (SELECT MAX(id)  FROM location)");

while($row=mysql_fetch_assoc($last))
$output[]=$row;
 print(json_encode($output));

mysql_close();
?>

</body>
</html>

Answer 1

Your PHP page contains HTML tags:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Gps Send</title>
</head>
<body>



[{"Lat":"47.9255072","Lon":"-97.0846979","id":"34"}]
</body>
</html>

Therefore, the error you are getting is because Android doesn't understand the response correctly (it assumes pure JSON, not HTML). You need to remove the HTML tags so the response only contains the pure JSON.

You might also want to set a header declaring it of a JSON content-type. You can do that this way:

header('Content-type: application/json');

Put this code right after the first <?php tag, before everything else.

Answer 2

Here's a class from my personal project: http://developersfound.com/HttpPostThreadJSon.zip This class will only work with verb POST but should be easy enough to refactor for use with other verbs.

package com.DevFound;

import org.apache.http.HttpResponse;
import org.apache.http.HttpVersion;
import org.apache.http.ProtocolVersion;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicHttpResponse;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONTokener;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class HttpPostThreadJSon {
    private static final int SUCCESS = 1;
    private static final int FAILURE = 0;

    protected static JSONArray doInBackground(HttpPost HttpPostObj) {
        HttpClient HttpClientObj = new DefaultHttpClient();
        ProtocolVersion ProtocolVersionObj = new HttpVersion(1, 1);
        Integer codeVar = 0;
        String ReasonObj = "";
        HttpResponse HttpResponseObj = new BasicHttpResponse(ProtocolVersionObj, codeVar, ReasonObj);
        try {
            HttpResponseObj = HttpClientObj.execute(HttpPostObj);
        } catch (IOException e) {
            e.printStackTrace();
        }
        StringBuilder stringBuilder = new StringBuilder();
        String line;
        BufferedReader bufferedReader = null;
        try {
            bufferedReader = new BufferedReader(new InputStreamReader(HttpResponseObj.getEntity().getContent()));
        } catch (IOException e) {
            e.printStackTrace();
        }
        try {
            while ((line = bufferedReader.readLine()) != null) {
                stringBuilder.append(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        JSONTokener tokener = new JSONTokener(stringBuilder.toString());
        JSONArray result = null;
        try {
            result = new JSONArray(tokener);
            return result;
        } catch (JSONException e) {
            //e.printStackTrace();
        }
        return result;
    }
}

From the client class you would have to build the post Object with something like:

HttpPostObj = new HttpPost((DGSession.getSessionStr("HttpPost", getBaseContext()) + "login.php"));

Answer 3

$last =mysql_query("SELECT * FROM location WHERE ID = (SELECT MAX(id) FROM location)");

i know this question is solved a long time ago but the mysql query you use isn't the best way to fetch the result. You execute a Select in a Select so it means it will search two times in the location tabel. a much better way would be

"SELECT * FROM location ORDER BY id DESC LIMIT 1"

this would fetch the row with the highest id, the result of both query's is still equal but the execution time of the query with just 1 Select is faster than the query with 2 Select's.