如何在 Dart 中上传文件?

本文介绍了如何在 Dart 中上传文件?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我正在尝试查找使用 Dart 脚本上传文件的任何示例.

I'm trying to find any examples of uploading a file with a Dart script.

我了解在文件输入字段中被选中后在客户端读取它的部分，但是我如何将它POST到服务器并将其保存为文件?

I understand the part about reading it on the client side after being selected in a file input field, but how can I POST it to the server and save it as a file?

推荐答案

在多部分编码解析器可用之前，您可以使用 文件 API 在客户端读取和上传文件内容为 dataUrl.这个 API 在浏览器中有很好的支持(见 caniuse/filereader).

Until a multipart encoding parser is available, you can use File API on client to read and upload file content as dataUrl. This API has quite good support in browsers ( see caniuse/filereader ).

在客户端:

import 'dart:html'; main() { InputElement uploadInput = query('#upload'); uploadInput.onChange.listen((e) { // read file content as dataURL final files = uploadInput.files; if (files.length == 1) { final file = files[0]; final reader = new FileReader(); reader.onLoad.listen((e) { sendDatas(reader.result); }); reader.readAsDataUrl(file); } }); } /// send data to server sendDatas(dynamic data) { final req = new HttpRequest(); req.onReadyStateChange.listen((Event e) { if (req.readyState == HttpRequest.DONE && (req.status == 200 || req.status == 0)) { window.alert("upload complete"); } }); req.open("POST", "127.0.0.1:8080/upload"); req.send(data); }

在服务器端:

import 'dart:io'; main() { final server = new HttpServer(); server.listen('127.0.0.1', 8080); server.addRequestHandler((request) => request.path == '/upload' && request.method.toLowerCase() == 'post' , (HttpRequest request, HttpResponse response) { _readBody(request, (body) { // handle your dataURL // example with image : data:image/jpeg;base64,/9j/4S2YRXhpZgAATU0AK... // return result response.statusCode = HttpStatus.CREATED; response.contentLength = 0; response.outputStream.close(); }); }); } /// Read body of [request] and call [handleBody] when complete. _readBody(HttpRequest request, void handleBody(String body)) { String bodyString = ""; // request body byte data final completer = new Completer(); final sis = new StringInputStream(request.inputStream, Encoding.UTF_8); sis.onData = (){ bodyString = bodyString.concat(sis.read()); }; sis.onClosed = () { completerplete(""); }; sis.onError = (Exception e) { print('exeption occured : ${e.toString()}'); }; // process the request and send a response completer.future.then((_){ handleBody(bodyString); }); }

参考资料:

• 使用文件 API 在 JavaScript 中读取文件