Créer un session en android

package com.example.mainviewactivity;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;

import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.R.string;
import android.net.ParseException;
import android.os.Bundle;
import android.app.Activity;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.content.Intent;
import android.content.SharedPreferences;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity  {
	EditText etUser ;
    EditText etPass ;
    Button bLogin ;
    String username;
	String password;
    HttpClient httpclient ;
    HttpPost httppost;
    ArrayList<NameValuePair> nameValuePairs ;
    HttpResponse response;
    HttpEntity entity ;
    String EXTRA_LOGIN="login";

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initialise();
    }
    private void initialise() 
    {
    	etUser = (EditText) findViewById(R.id.user_email);
        etPass = (EditText) findViewById(R.id.user_password);
        bLogin = (Button) findViewById(R.id.connect);
        bLogin.setOnClickListener(new View.OnClickListener() {

public void onClick(View v) 
            {
        	httpclient = new DefaultHttpClient();
        	 httppost = new HttpPost("http://10.0.2.2/android_connect/index.php");
        	username=etUser.getText().toString();
            password= etPass.getText().toString();
            //URL url=new URL(LoginDisplayActivity.);
           
            try{
            	 nameValuePairs =new ArrayList<NameValuePair>();
            	 nameValuePairs.add(new BasicNameValuePair("username",username));
                 nameValuePairs.add(new BasicNameValuePair("password",password));
            	httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            	response = httpclient.execute(httppost);
            	if(response.getStatusLine().getStatusCode()==200){
            		entity = response.getEntity();
            		if(entity!=null){
            			InputStream instream=entity.getContent();
            			JSONObject jsonResponse=new JSONObject(convertStreamToString(instream));
            			String retUser=jsonResponse.getString("username");
            			String retPasss=jsonResponse.getString("userpass");
            			// validate login
            			if(username.equals(retUser)&& password.equals(retPasss)){
            				/*SharedPreferences sp=getSharedPreferences("logindetails", 0);
            				SharedPreferences.Editor spedit=sp.edit();
            				spedit.putString("username",username);
            				spedit.putString("userpass",password);//may not need to store password
            				// close editor
            				spedit.commit();*/
            				etUser.setText("");
        	    			etPass.setText("");
        	    			Intent intent = new Intent(MainActivity.this, LoginDisplayActivity.class);
        	    	      	//intent.putExtra(EXTRA_LOGIN, etUser.getText().toString());
        	    	    	//intent.putExtra(EXTRA_PASSWORD, pass.getText().toString());
        	    	      	startActivity(intent);
            			}
            			else{
            				Toast.makeText(MainActivity.this,
            	                    R.string.champs_erronees,
            	                    Toast.LENGTH_SHORT).show();
            	                    return;
            			}
            		}
            	}
            	
            }catch(Exception e){
            	e.printStackTrace();
            	Toast.makeText(MainActivity.this,
	                    R.string.champs_erronees,
	                    Toast.LENGTH_SHORT).show();
	                    return;
            }
        	
            }//end on click
  		
  	                                                         });
          
    } //end initialise  

private static String convertStreamToString(InputStream is) {
            
            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();
        }

}