org.apache.http.conn.HttpHostConnectException：拒绝连接http://10.0.2.2

Question

I had been going through almost every answer related to this topic but still, I'm stuck at this issue. I'm using ubuntu and phone as my emulator which s connected by USB. Also I'm using Postgresql with LAPP. So kindly help me with this.

package com.example.testingdatabase;

import android.os.AsyncTask;
import android.util.Log;
import android.widget.EditText;
import android.widget.Toast;

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

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

public class test extends AsyncTask {
    String name;
    String password;

    String desig;
    InputStream is=null;
    String result=null;
    String line=null;
    int code;
    EditText namee;
    EditText pass;
    EditText desi;

    @Override
    protected Object doInBackground(Object[] objects) {
        ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();

        nameValuePairs.add(new BasicNameValuePair("name", name));
        nameValuePairs.add(new BasicNameValuePair("password", password));
        nameValuePairs.add(new BasicNameValuePair("desig", desig));

        try {
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("http://10.0.2.2/project/insert.php");
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            HttpResponse response = httpclient.execute(httppost);
            HttpEntity entity = response.getEntity();
            is = entity.getContent();
            Log.e("pass 1", "connection success ");
        } catch (Exception e) {
            Log.e("Fail 1", e.toString());
            System.out.println("sorry,invalid ip");
            //  Toast.makeText(getApplicationContext(), "Invalid IP Address",Toast.LENGTH_LONG).show();
        }

        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            while ((line = reader.readLine()) != null) {
                sb.append(line + "
");
            }
            is.close();
            result = sb.toString();
            Log.e("pass 2", "connection success ");
        } catch (Exception e) {
            Log.e("Fail 2", e.toString());
        }

        try {
            JSONObject json_data = new JSONObject(result);
            code = (json_data.getInt("code"));

            if (code == 1) {
                System.out.println("sucess");
                //Toast.makeText(getBaseContext(),"Inserted Successfully", Toast.LENGTH_SHORT).show();
            } else {
                System.out.println("sorry");
                //Toast.makeText(getBaseContext(),"Sorry, Try Again", Toast.LENGTH_LONG).show();
            }
        } catch (Exception e) {
             Log.e("Fail 3", e.toString());
        }    
        return null;
    }
}