How To Open A Word or PDF Document On Android

permission_handler: ^6.1.1
pdftron_flutter:
  git:
    url: git://github.com/PDFTron/pdftron-flutter.git

<application
	android:name="io.flutter.app.FlutterApplication"
	android:label="myapp"
	android:icon="@mipmap/ic_launcher"
	android:largeHeap="true"
android:usesCleartextTraffic="true"

>

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

import 'dart:async';
import 'dart:io' show Platform;

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:pdftron_flutter/pdftron_flutter.dart';
import 'package:permission_handler/permission_handler.dart';

void main() {
  runApp(PDFViewer());
}

class PDFViewer extends StatefulWidget {
  @override
  _PDFViewerState createState() => _PDFViewerState();
}

class _PDFViewerState extends State<PDFViewer> {
  String _pdf = "https://pdftron.s3.amazonaws.com/downloads/pl/PDFTRON_mobile_about.pdf";
  String _document = "https://file-examples-com.github.io/uploads/2017/02/file-sample_100kB.doc";

  @override
  void initState() {
    super.initState();
    initPlatformState();

    if (Platform.isIOS) {

    } else {
      // Request for permissions for android before opening document
      launchWithPermission();
    }
  }

  Future<void> launchWithPermission() async {
    Map<Permission, PermissionStatus> permissions =await [Permission.storage,].request();

    if (granted(permissions[Permission.storage])) {

    }
  }

  // Platform messages are asynchronous, so we initialize in an async method.
  Future<void> initPlatformState() async {
    String version;
    // Platform messages may fail, so we use a try/catch PlatformException.
    try {
      PdftronFlutter.initialize("Insert commercial license key here after purchase");
      version = await PdftronFlutter.version;
    } on PlatformException {
      version = 'Failed to get platform version.';
    }

    // If the widget was removed from the tree while the asynchronous platform
    // message was in flight, we want to discard the reply rather than calling
    // setState to update our non-existent appearance.
    if (!mounted) return;


  }


  void showViewer(file) {
    PdftronFlutter.openDocument(file);
  }

  bool granted(PermissionStatus status) {
    return status == PermissionStatus.granted;
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        backgroundColor: Colors.greenAccent,
        appBar: AppBar(
          backgroundColor: Colors.green,
          title: const Text('PDFTron flutter app'),
        ),
        body: Center(
          child: GridView(
            gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 2),
            children: [
              Card(
                elevation: 10,
                child: FlatButton(child: Text("View Doc",style: TextStyle(fontSize: 20),),color:Colors.blueGrey,textColor:Colors.white,highlightColor: Colors.red,onPressed: (){
                  showViewer(_document);
                },),
              ),
              Card(
                elevation: 10,
                child: FlatButton(child: Text("View PDF",style: TextStyle(fontSize: 20)),color:Colors.brown,textColor:Colors.white,highlightColor: Colors.red,onPressed: (){
                  showViewer(_pdf);
                },),
              )
            ],
          ),
          /*,*/
        ),
      ),
    );
  }
}