如何在Flutter中通过WebView下载/创建pdf [英] how to download/create pdf through webview in flutter

问题描述

我创建了一个webview脚手架，但是在从webview浏览时无法下载任何内容，但是当我单击按钮时它什么也没做。我不知道从哪里开始，就像其他可以下载和预览的浏览器一样，我正在尝试在这里实现相同的目标。

I have created a webviewscaffold but can't download anything from it while browsing from the webview, I made but when I click the button it does nothing. I don't know where to start, like in other browsers that can download and preview, I'm trying to achieve the same thing in here.

class AppState extends State<App> {


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Stack(
        children: <Widget>[
          Align(
            alignment: Alignment(1, 1),
            child: Container(
              child: Web(), // it is a statefulwidget that have WebviewScaffold, i have created it on a new page and imported/used here
            ),
          ),
          Column(
            mainAxisAlignment: MainAxisAlignment.end,
            children: <Widget>[
              Padding(
                padding: EdgeInsets.only(top: 20.0),
              )
            ],
          ),
          Align(
            alignment: Alignment(0.7, -0.93),
            child: FloatingActionButton(
                tooltip: "Share",
                child: Icon(
                  Icons.share,
                  color: Colors.amberAccent,
                ),
                onPressed: () {
                  _onShareTap();
                }),
          ),
        ],
      ),
    );
  }

我希望，当我单击Web视图中的打印或下载按钮时，

I expect, when I click the print or download button within the webview it should work like any other browser.

推荐答案

您可以使用我的插件 flutter_inappwebview ，这是Flutter插件，可让您添加内联WebView或打开应用内浏览器窗口，并具有许多事件，方法和选项来控制WebView

You can use my plugin flutter_inappwebview, which is a Flutter plugin that allows you to add inline WebViews or open an in-app browser window and has a lot of events, methods, and options to control WebViews.

要能够识别可下载文件，您需要设置 useOnDownloadStart：true 选项，然后您需要可以收听 onDownloadStart 事件！

To be able to recognize downloadable files, you need to set the useOnDownloadStart: true option, and then you can listen the onDownloadStart event!

此外，例如，在Android上，您需要在 AndroidManifest.xml 文件：

Also, for example, on Android you need to add write permission inside your AndroidManifest.xml file:

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

然后，您需要使用 permission_handler 插件。相反，要有效下载文件，可以使用 flutter_downloader 插件。

Then, you need to ask permission using the permission_handler plugin. Instead, to effectively download your file, you can use the flutter_downloader plugin.

以下是使用 http://ovh.net/files/（尤其是 http://ovh.net/files/1Mio.dat URL）以测试下载：

Here is a complete example using http://ovh.net/files/ (in particular, the http://ovh.net/files/1Mio.dat as URL) to test the download:

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_inappwebview/flutter_inappwebview.dart';
import 'package:flutter_downloader/flutter_downloader.dart';
import 'package:path_provider/path_provider.dart';
import 'package:permission_handler/permission_handler.dart';

Future main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await FlutterDownloader.initialize(
      debug: true // optional: set false to disable printing logs to console
  );
  await Permission.storage.request();
  runApp(new MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  InAppWebViewController webView;

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

  @override
  void dispose() {
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('InAppWebView Example'),
        ),
        body: Container(
            child: Column(children: <Widget>[
          Expanded(
              child: InAppWebView(
            initialUrl: "http://ovh.net/files/1Mio.dat",
            initialHeaders: {},
            initialOptions: InAppWebViewGroupOptions(
              crossPlatform: InAppWebViewOptions(
                debuggingEnabled: true,
                useOnDownloadStart: true
              ),
            ),
            onWebViewCreated: (InAppWebViewController controller) {
              webView = controller;
            },
            onLoadStart: (InAppWebViewController controller, String url) {

            },
            onLoadStop: (InAppWebViewController controller, String url) {

            },
            onDownloadStart: (controller, url) async {
              print("onDownloadStart $url");
              final taskId = await FlutterDownloader.enqueue(
                url: url,
                savedDir: (await getExternalStorageDirectory()).path,
                showNotification: true, // show download progress in status bar (for Android)
                openFileFromNotification: true, // click on notification to open downloaded file (for Android)
              );
            },
          ))
        ])),
      ),
    );
  }
}

在这里，如您所见，我正在使用还有 path_provider 插件来获取我要保存文件的文件夹。

Here, as you can see, I'm using also the path_provider plugin to get the folder where I want to save the file.

这篇关于如何在Flutter中通过WebView下载/创建pdf的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！