Android PHP MySQL应用程序可在api 26和27上运行，但不能在28上运行

Question

大约一年前，我有一个需要登录功能的应用程序，我遵循了将PHP用于Android应用程序以与MySQL数据库对话的指南。效果很好，我用Oreo（API 26和27）在手机上很好地完成了任务。

但是现在我需要类似的功能才能在新项目中再次工作，这些应用程序无法在Android Pie（API 28）上运行。

Login.java

import android.content.Intent;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;


import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.toolbox.Volley;

import org.json.JSONException;
import org.json.JSONObject;

public class Login extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        final EditText et_log, et_pw;
        final Button bt_log;

        et_log = (EditText) findViewById(R.id.et_login);
        et_pw = (EditText) findViewById(R.id.et_password);
        bt_log = (Button) findViewById(R.id.bt_login);

        bt_log.setOnClickListener(new View.OnClickListener() {


            @Override
            public void onClick(View v) {

                final String ID = et_log.getText().toString();
                final String PW = et_pw.getText().toString();
                Response.Listener<String> respondslistener = new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {
                        try {
                            JSONObject jsonresponse = new JSONObject(response);
                            boolean success = jsonresponse.getBoolean("success");
                            if(success){
                                String Name = jsonresponse.getString("name");
                                String Position = jsonresponse.getString("position");

                                Intent intent = new Intent(Login.this, MainActivity.class);
                                intent.putExtra("name",Name);
                                intent.putExtra("position",Position);
                                intent.putExtra("ID",ID);
                                Login.this.startActivity(intent);
                                finish();
                            }
                            else{
                                AlertDialog.Builder builder = new AlertDialog.Builder(Login.this);
                                builder.setMessage("Login failed")
                                        .setNegativeButton("Retry",null)
                                        .create()
                                        .show();
                            }
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                };


                Loginrequest loginrequest = new Loginrequest(ID,PW, respondslistener);
                RequestQueue queue = Volley.newRequestQueue(Login.this);
                queue.add(loginrequest);
            }
        });

    }
}

Loginrequest.java

import com.android.volley.Response;
import com.android.volley.toolbox.StringRequest;

import java.util.HashMap;
import java.util.Map;

public class Loginrequest extends StringRequest {
    private static final String LOGIN_REQUEST_URL ="http://private-ip/login.php";
    private Map<String, String> params;

    public Loginrequest(String ID, String PW, Response.Listener<String> listener){
        super(Method.POST, LOGIN_REQUEST_URL, listener, null);
        params = new HashMap<>();
        params.put("ID",ID);
        params.put("PW",PW);
    }

    @Override
    public Map<String, String> getParams() {
        return params;
    }

和login.php将返回类似的内容

{"success":true,"name":"Jeff","position":"IT"}

是否可以使其在Pie上运行？我需要更改什么？