如何在Dart中上传文件? [英] How to upload a file in Dart?
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问题描述
我试图找到使用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.
我理解了在选择之后在客户端阅读的部分一个文件输入字段,但是如何POST到服务器并保存为一个文件?
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
解析器,则可以在客户端上使用 File API 来阅读和上传文件内容作为 dataUrl 。此API在浏览器中提供了相当好的支持(请参阅 http://caniuse.com/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 http://caniuse.com/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", "http://127.0.0.1:8080/upload");
req.send(data);
}
而在服务器端:
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 = () {
completer.complete("");
};
sis.onError = (Exception e) {
print('exeption occured : ${e.toString()}');
};
// process the request and send a response
completer.future.then((_){
handleBody(bodyString);
});
}
参考文献:
- Reading files in JavaScript using the File APIs
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