<?php session_start();$con= mysql_connect("MySQL User Name","MySQL Host Name","password");mysql_select_db("MySQL DB Name",$con);$userName=$_POST['username'];$password=$_POST['password'];$sql1="SELECT * FROM log_in WHERE username='$username'";$result = mysql_query($sql1);$r=mysql_fetch_array($result);if($r[1]== ""){print "no user";}else if (($password != $r[2]) || ($username != $r[1])){print "error username or password";}else {print "ok";}mysql_close($con);?>

public class log_in extends AsyncTask{ private String Link, username, password;public log_in(String link,String username,String password) {Link = link;this.username = username;this.password = password;} @Override protected Object doInBackground(Object[] objects) {try {  String data=URLEncoder.encode("user","UTF-8")+"="+URLEncoder.encode(username,"UTF-8");data+= "&" + URLEncoder.encode("password","UTF-8")+"="+URLEncoder.encode(password,"UTF-8");URL con = new URL(Link); URLConnection connect=con.openConnection();connect.setDoOutput(true);OutputStreamWriter wr= new OutputStreamWriter(connect.getOutputStream());wr.write(data);wr.close();BufferedReader read=new BufferedReader(new InputStreamReader(connect.getInputStream()));StringBuilder sb=new StringBuilder();String line=null;while ((line=read.readLine())!=null){sb.append(line);}ManagementActivity.r = sb.toString();}catch (Exception e){}return null;}}

public class ManagementActivity extends AppCompatActivity {   Button managementEnterBtn;   EditText edtUser, edtPass;    public static  String r = "";   @Override   protected void onCreate(Bundle savedInstanceState) {       super.onCreate(savedInstanceState);       setContentView(R.layout.activity_management);        managementEnterBtn = (Button) findViewById(R.id.managementEnterBtn);        edtUser = (EditText) findViewById(R.id.edtUser);       edtPass = (EditText) findViewById(R.id.edtPass);   managementEnterBtn.setOnClickListener(new View.OnClickListener({            @Override           public void onClick(View view{          login(edtUser.getText().toString(),edtPass.getText().toString());                Log.i("Log:","تابع صدا زده شد");           }        });    }  private  void  login(String username,String password){        Log.i("Log:","وارد تابع شد");      new log_in("http://appalborz.webpi.ir/log_in.php?i=1",username,password).execute();       Log.i("Log:","شی جدید از روی کلاس ساخته شد");        final Timer t=new Timer();       Log.i("Log:","وارد تایمر شد");       t.scheduleAtFixedRate(new TimerTask() {          @Override           public void run() {               runOnUiThread(new Runnable() {                    @Override                  public void run()                   {                        switch (r){                           case ("ok"):{                                Log.i("LOG:","شرط اول برقرار شد");                               Toast.makeText(ManagementActivity.this, "نام کاربری و کلمه عبور صحیح است", Toast.LENGTH_SHORT).show();                               break;                          }                          case ("no user"):                           {                                Log.i("LOG:","شرط دوم برقرار شد");                             Toast.makeText(ManagementActivity.this, "نام کاربری و کلمه عبوری وارد نشده است", Toast.LENGTH_SHORT).show();                         break;                          }                           case ("error username or password"):                            {                        Log.i("LOG:","شرط سوم برقرار شد");Toast.makeText(ManagementActivity.this, "نام کاربری یا کلمه عبور اشتباه است", Toast.LENGTH_SHORT).show();break;}}}}); }},1,1000);}}