Question

如何在Dart上从客户端，服务器上读取POST方法发送的HttpRequest数据？

我从客户端发送消息，如下所示：

HttpRequest request = new HttpRequest();
var url = "http://127.0.0.1:8081";
request.open("POST", url, async: false);

String data = 'hello from client'; 
request.send(data);

在服务器上，我正在捕捉这样的请求：

HttpServer.bind('127.0.0.1', 8081).then((server) {
server.listen((HttpRequest request) {

//DATA SHOULD BE READ HERE 



});
});

但我无法弄清楚如何实际读取数据... HttpRequest中没有数据属性也没有其他...

编辑这是我现在得到答案的方式：

HttpServer.bind('127.0.0.1', 8081).then((server) {
server.listen((HttpRequest request) {
  //DATA SHOULD BE READ HERE 
  print("got it");
  print(request.method);
  if(request.method == "POST") {
    print("got it 2");
    List<int> dataBody = new List<int>();
    request.listen(dataBody.addAll, onDone: () {
      var postData = new String.fromCharCodes(dataBody);
      print(postData);
      });
    }
 });
});

但由于某种原因，request.method不是“POST”而是“OPTIONS”，如果我改为if(request.method == "OPTIONS")，那么print（postData）仍然不会返回任何内容......

Answer 1

目前，处理POST数据有点困难。但基本上HttpRequest本身必须“倾听”。 HttpRequest is a stream itself。特别是它是Stream<List<int>>。所以基本上你的数据可以作为多个List<int>传递给你的HttpRequest。所以我们需要重建数据然后将其转换为字符串（假设你期望一个字符串，而不是二进制数据等）。这或多或少都是我做的：

HttpServer.bind('127.0.0.1', 8081).then((server) {
  server.listen((HttpRequest request) {
  if(request.method == "POST") {
    List<int> dataBody = new List<int>();
    request.listen(dataBody.addAll, onDone: () {
      var postData = new String.fromCharCodes(dataBody);
      // Do something with the data now.
    });
  }
  request.response.close();
});

请注意，每次数据发送到服务器时，request.listen(dataBody.AddAll, ...)基本上都会调用List.addAll()（如果数据较大或多部分形式，则可能不会同时出现）。这确保我们缓冲所有内容，直到流表明它已“完成”。在这种情况下，我们现在可以对收到的数据执行某些操作，例如将其转换为字符串。

Answer 2

您可以使用StringDecoder从HttpRequest中的“List of Int”转换为“String”。因为无论你发送json，纯文本还是png，Dart总是以数据的形式发送数据服务器的“Int列表”。另一种方法是使用在Heroku Steam上测试的Streams（http://www.dartlang.org/articles/feet-wet-streams/）v0.6.2 Dart编辑器0.4.3_r20602 Dat SDK 0.4.3.5_r26062

例如，

客户：

 import 'dart:html';
 import 'dart:json' as Json;
 import 'dart:async';
 import 'dart:uri';
 final String data = 'Hello World!';
 void _sendPNG(String pngData) {
 HttpRequest request = new HttpRequest(); // create a new XHR
 // add an event handler that is called when the request finishes
 request.onReadyStateChange.listen((_) 
 {
 if (request.readyState == HttpRequest.DONE &&
 (request.status == 200 || request.status == 0)) {
 // data saved OK.
 print(request.responseText); // output the response from the server
 }
                  }
 );
 // POST the data to the server Async
 print('Sending Photos to the server...');
 var url = "/png";
 request.open("POST", url);
 request.setRequestHeader("Content-Type", "text/plain");
 request.send(data);
 }

服务器：

 import 'dart:io';
 import 'dart:async';
 import 'dart:json' as Json;
 import "package:stream/stream.dart";
 import 'package:xml/xml.dart' as xml;
 import 'package:unittest/unittest.dart';
 import 'package:rikulo_commons/mirrors.dart';
 void receivePNG(HttpConnect connect){
 var request = connect.request;
 var response = connect.response;
 if(request.uri.path == '/png' && request.method == 'POST')
  {
   String png='';
   response.write('The server received png request!');
   //read incoming List<int> data from request and use StringDecoder to transform   incoming data to string
   var stream = request.transform(new StringDecoder());
   stream.listen((value){
   print(value);
   //Hello World!
  }
  else
  {
   response.write('error');
   response.statusCode = HttpStatus.NOT_FOUND;
   connect.close();
   }
  }

configure.dart

 var _mapping = {
  "/": home,
  "/png": receivePNG,
 };

Answer 3

我在客户端/侧码

中找到了这个有用的例子

GitHub json send to server Example

// XXX: Dart Editor thinks this is OK, but I haven't run it.

import 'dart:html';

String encodeMap(Map data) {
  return data.keys.map((k) {
    return '${Uri.encodeComponent(k)}=${Uri.encodeComponent(data[k])}';
  }).join('&');
}

loadEnd(HttpRequest request) {
  if (request.status != 200) {
    print('Uh oh, there was an error of ${request.status}');
    return;
  } else {
    print('Data has been posted');
  }
}

main() {
  var dataUrl = '/registrations/create';
  var data = {'dart': 'fun', 'editor': 'productive'};
  var encodedData = encodeMap(data);

  var httpRequest = new HttpRequest();
  httpRequest.open('POST', dataUrl);
  httpRequest.setRequestHeader('Content-type', 
                               'application/x-www-form-urlencoded');
  httpRequest.onLoadEnd.listen((e) => loadEnd(httpRequest));
  httpRequest.send(encodedData);
}

如何在服务器上读取客户端发送的Http Request数据

3 个答案: