我正在尝试使用php连接一个带有e登录和注册的应用程序这是android连接部分的代码，url使用ftp连接mysql数据库：

public class BackgroundTask extends AsyncTask<String,Void,String> {

SharedPreferences preferences;
SharedPreferences.Editor editor;

Context context;

BackgroundTask(Context ctx){
    this.context = ctx;
}

@Override
protected String doInBackground(String... params) {

    preferences = context.getSharedPreferences("MYPREFS", Context.MODE_PRIVATE);
    editor = preferences.edit();
    editor.putString("flag","0");
    editor.commit();

    String urlRegistration = "ftp://remoteaddress/site/wwwroot/classes/LoginAndRegister-register.php";
    String urlLogin  = "ftp://remoteaddress/site/wwwroot/classes/LoginAndRegister-login.php";
    String task = params[0];

    if(task.equals("register")){
        String regName = params[1];
        String regEmail = params[2];
        String regPassword = params[3];

        try {
            URL url = new URL(urlRegistration);
            HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
            httpURLConnection.setRequestMethod("POST");
            httpURLConnection.setDoOutput(true);
            OutputStream outputStream = httpURLConnection.getOutputStream();
            OutputStreamWriter outputStreamWriter = new OutputStreamWriter(outputStream,"UTF-8");
            BufferedWriter bufferedWriter = new BufferedWriter(outputStreamWriter);
            String myData = URLEncoder.encode("identifier_name","UTF-8")+"="+URLEncoder.encode(regName,"UTF-8")+"&"
                    +URLEncoder.encode("identifier_email","UTF-8")+"="+URLEncoder.encode(regEmail,"UTF-8")+"&"
                    +URLEncoder.encode("identifier_password","UTF-8")+"="+URLEncoder.encode(regPassword,"UTF-8");
            bufferedWriter.write(myData);
            bufferedWriter.flush();
            bufferedWriter.close();
            InputStream inputStream = httpURLConnection.getInputStream();
            inputStream.close();

            editor.putString("flag","register");
            editor.commit();
            return "Successfully Registered " + regName;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
    if(task.equals("login")){
        String loginEmail = params[1];
        String loginPassword = params[2];
        try {
            URL url = new URL(urlLogin);
            HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
            httpURLConnection.setRequestMethod("POST");
            httpURLConnection.setDoOutput(true);
            httpURLConnection.setDoInput(true);

            //send the email and password to the database
            OutputStream outputStream = httpURLConnection.getOutputStream();
            OutputStreamWriter outputStreamWriter = new OutputStreamWriter(outputStream,"UTF-8");
            BufferedWriter bufferedWriter = new BufferedWriter(outputStreamWriter);
            String myData = URLEncoder.encode("identifier_loginEmail","UTF-8")+"="+URLEncoder.encode(loginEmail,"UTF-8")+"&"
                    +URLEncoder.encode("identifier_loginPassword","UTF-8")+"="+URLEncoder.encode(loginPassword,"UTF-8");
            bufferedWriter.write(myData);
            bufferedWriter.flush();
            bufferedWriter.close();
            outputStream.close();

            //get response from the database
            InputStream inputStream = httpURLConnection.getInputStream();
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream,"UTF-8");
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String dataResponse = "";
            String inputLine = "";
            while((inputLine = bufferedReader.readLine()) != null){
                dataResponse += inputLine;
            }
            bufferedReader.close();
            inputStream.close();
            httpURLConnection.disconnect();

            System.out.println("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
            System.out.println(dataResponse);

            editor.putString("flag","login");
            editor.commit();
            return  dataResponse;

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    return null;
}

@Override
protected void onPreExecute() {
    super.onPreExecute();
}

//This method willbe called when doInBackground completes... and it will return the completion string which
//will display this toast.
@Override
protected void onPostExecute(String s) {
    String flag = preferences.getString("flag","0");

    if(flag.equals("register")) {
        Toast.makeText(context,s,Toast.LENGTH_LONG).show();
    }
    if(flag.equals("login")){
        String test = "false";
        String name = "";
        String email = "";
        String[] serverResponse = s.split("[,]");
        test = serverResponse[0];
        name = serverResponse[1];
        email = serverResponse[2];

        if(test.equals("true")){
            editor.putString("name",name);
            editor.commit();
            editor.putString("email",email);
            editor.commit();
            Intent intent = new Intent(context,LogginIn.class);
            context.startActivity(intent);
        }else{
            display("Login Failed...", "That email and password do not match our records :(.");
        }
    }else{
        display("Login Failed...","Something weird happened :(.");
    }
}

@Override
protected void onProgressUpdate(Void... values) {
    super.onProgressUpdate(values);
}

public void display(String title, String message){
    AlertDialog.Builder builder = new AlertDialog.Builder(context);
    builder.setCancelable(true);
    builder.setTitle(title);
    builder.setMessage(message);
    builder.show();
}
}

以下是php连接：

<?
 $hostname = "us-cdbr-azure-southcentral-f.cloudapp.net";
 $username = "XXXXX";
 $dbname = "db";
 $password = "word";

 //Create connection
 $conn = mysql_connect($hostname, $username, $password);
 $selectdb=mysql_select_db($dbname);
 //Check connection
 if(!$conn){
//die("Connectioned failed!" . mysql_connect_error());
}
else{
//echo "Connect success!";
}
?>

并且login.php密码是加密的，所以我使用sha1（）“x”来尝试获取密码：

<?php
 require "LoginAndRegister-connection.php";

 $user_email = $_POST["identifier_loginEmail"];
 $user_pass =  $_POST["identifier_loginPassword"];

 $mysql_query = "SELECT * FROM usuarios WHERE email = '$user_email'
 AND senha = '$user_pass'";

$result = mysql_query($conn,$mysql_query);

 //check the result
 if(mysql_num_rows($result)>0){
$row = mysql_fetch_assoc($result);
$name = $row["name"];
$email = $row["email"];

//Here is the specially formatted string response.. ie: "ServerResponse".
//It is of the form: "boolean,email,name"
echo "true,".$email.",".$name;
}
else{
echo "Login was not successful... :(";
}

?>

当我运行代码时，当我尝试登录app:java.lang.classcastexception:sun.net时，会出现此错误。www.protocol.ftp.ftpurlconnection 无法转换为java.net.httpurlconnection
有人能告诉我哪里犯的错吗？