How to save and download text file in Flutter web application

问题

I am new to Flutter and working in a flutter web application, My requirement is to create and download a text file. like below.

void getData() {
    List<int> bytes = utf8.encode('this is the text file');
    print(bytes); // Need to download this with txt file.
}

Can anyone help me to achieve this

回答1:

This method is based on manipulations with an HTML document. Some additional packages should be imported:

import 'dart:convert';
import 'dart:html' as html; // or package:universal_html/prefer_universal/html.dart

Code snippet:

final text = 'this is the text file';

// prepare
final bytes = utf8.encode(text);
final blob = html.Blob([bytes]);
final url = html.Url.createObjectUrlFromBlob(blob);
final anchor = html.document.createElement('a') as html.AnchorElement
  ..href = url
  ..style.display = 'none'
  ..download = 'some_name.txt';
html.document.body.children.add(anchor);

// download
anchor.click();

// cleanup
html.document.body.children.remove(anchor);
html.Url.revokeObjectUrl(url);

Here is DartPad demo.

回答2:

Got another way to do it, via popular JS library called FileSaver

First, update your ProjectFolder/web/index.html file to include the library and define the webSaveAs function like so:

...

<script src="https://cdnjs.cloudflare.com/ajax/libs/FileSaver.js/1.3.8/FileSaver.min.js"> 
</script>

<script>
function webSaveAs(blob, name) {
  saveAs(blob, name);
}
</script>

<script src="main.dart.js" type="application/javascript"></script>

...

Then you can call this function from Dart code like so:

import 'dart:js' as js;
import 'dart:html' as html;

...

js.context.callMethod("webSaveAs", [html.Blob([bytes], "test.txt"])

回答3:

This solution uses FileSaver.js library and it should open the "saveAs" dialog.

I hope it works as intended:

import 'dart:js' as js;
import 'dart:html' as html;

...

final text = 'this is the text file';
final bytes = utf8.encode(text);

final script = html.document.createElement('script') as html.ScriptElement;
script.src = "http://cdn.jsdelivr.net/g/filesaver.js";

html.document.body.nodes.add(script);

// calls the "saveAs" method from the FileSaver.js libray
js.context.callMethod("saveAs", [
  html.Blob([bytes]),
  "testText.txt",            //File Name (optional) defaults to "download"
  "text/plain;charset=utf-8" //File Type (optional)
]);

 // cleanup
 html.document.body.nodes.remove(script);

来源：https://stackoverflow.com/questions/59663377/how-to-save-and-download-text-file-in-flutter-web-application

标签

Flutter

dart

flutter-web