how to pass textformfield data to api?

[sona]

import 'dart:convert';

import 'package:flutter/material.dart';
import 'InputDeco_design.dart';
import 'package:http/http.dart' as http;


class FormPage extends StatefulWidget {
  final String text, text2;
FormPage({Key key, @required this.text,@required this.text2}) : super(key: key);
  @override
  _FormPageState createState() => _FormPageState(this.text,this.text2);
}

class _FormPageState extends State<FormPage> {
String text,text2;
_FormPageState(this.text,this.text2);
  //String stopname, platname, platdesc,direction, lat,lng,stop_name;

  TextEditingController _stopname = TextEditingController();
  TextEditingController _platname = TextEditingController();
  TextEditingController _platdesc = TextEditingController();
  TextEditingController _direction = TextEditingController();
  TextEditingController _lat= TextEditingController();
 TextEditingController _lng = TextEditingController();

  final GlobalKey<FormState> _formkey = GlobalKey<FormState>();


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: SingleChildScrollView(
          child: Form(
            key: _formkey,
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                CircleAvatar(
                  radius: 30,
                  backgroundColor: Colors.black,
                  child: Image.asset(
                    'assets/it.png', height: 50, width: 45,),
                ),
                SizedBox(
                  height: 15,
                ),
                Padding(
                  padding: const EdgeInsets.only(
                      bottom: 15, left: 10, right: 10),
                  child: TextFormField(
                    controller:_stopname,
                    keyboardType: TextInputType.text,
                    decoration: buildInputDecoration(Icons.person, "Stop Name"),
                    validator: (String value) {
                      if (value.isEmpty) {
                        return 'Please Enter a Stop Name';
                      }
                      return null;
                    },
                    onSaved: (String value) {
                      //stopname = value;
                    },
                  ),
                ),

                Padding(
                  padding: const EdgeInsets.only(
                      bottom: 15, left: 10, right: 10),
                  child: TextFormField(
                    controller:_platname,
                    keyboardType: TextInputType.text,
                    decoration: buildInputDecoration(
                        Icons.email, "Platform Name"),
                    validator: (String value) {
                      if (value.isEmpty) {
                        return 'Please Enter a Plat Name';
                      }

                      return null;
                    },
                    onSaved: (String value) {
                     // platname = value;
                    },
                  ),
                ),

                Padding(
                  padding: const EdgeInsets.only(
                      bottom: 15, left: 10, right: 10),
                  child: TextFormField(
                    controller:_platdesc,
                    keyboardType: TextInputType.number,
                    decoration: buildInputDecoration(
                        Icons.phone, "Plat Des"),
                    validator: (String value) {
                      if (value.isEmpty) {
                        return 'Please enter a Description ';
                      }
                      return null;
                    },
                    onSaved: (String value) {

                    },
                  ),
                ),
                Padding(
                  padding: const EdgeInsets.only(
                      bottom: 15, left: 10, right: 10),
                  child: TextFormField(
                    controller: _direction,
                    keyboardType: TextInputType.text,
                    decoration: buildInputDecoration(Icons.lock, "Towards"),
                    validator: (String value) {
                      if (value.isEmpty) {
                        return 'Please enter Towards';
                      }
                      return null;
                    },
                    onSaved: (String value) {
                     // direction= value;
                    },

                  ),
                ),

                Padding(
                  padding: const EdgeInsets.only(
                      bottom: 15, left: 10, right: 10),
                  child: TextFormField(

                    controller:TextEditingController.fromValue(
                      TextEditingValue(
                        text: text,
                        // selection: TextSelection.collapsed(offset: text.length),
                      ),
                    ),
                  ),
                ),

                Padding(
                  padding: const EdgeInsets.only(
                      bottom: 15, left: 10, right: 10),
                  child: TextFormField(
                    controller: TextEditingController.fromValue(
                      TextEditingValue(
                        text: text2,
                        // selection: TextSelection.collapsed(offset: text.length),
                      ),
                    ),
                  ),
                ),
                SizedBox(
                  width: 200,
                  height: 50,
                  child: RaisedButton(
                    color: Colors.redAccent,
                    onPressed: () {
                      if (_formkey.currentState.validate()) {
                        RegistrationUser(_stopname.toString(),_platname.toString(),_platdesc.toString(),_direction.toString(),text,text2);
                        print("successful");

                        return;
                      } else {
                        print("UnSuccessfull");
                      }
                    },
                    shape: RoundedRectangleBorder(
                        borderRadius: BorderRadius.circular(60.0),
                        side: BorderSide(color: Colors.blue, width: 2)
                    ),
                    textColor: Colors.white,
                    child: Text("Submit"),

                  ),
                )
              ],
            ),
          ),
        ),
      ),
    );
  }

Future RegistrationUser(String _stopname,String _platname,String _platdesc,String _direction,text, text2) async {
  var APIURL = "http://localhost:ip/add.hh?stop_name="+_stopname +"&plat_name="+_platname+"&plat_desc="+_platdesc+"&direction="+_direction+"&lat="+text+"&long="+text2+"";
 print("123");
  print(APIURL);
   Map mappeddata = {
      'stop_name': _stopname,
      'plat_name': _platname,
      'plat_desc': _platdesc,
      'direction': _direction,
      'lat': text,
      'long': text2,

    };
  print("hi");
  // print(text);
  print("JSON DATA: ${mappeddata}");
  http.Response reponse = await http.get(APIURL);
  //getting response from php code, here
  var data = jsonDecode(reponse.body);
  print("DATA: ${data}");
}}