来自nodejs

Question

我正在使用nodejs创建一个聊天室。我为此目的使用express，socket.io和http。我正在寻找通过http服务器进行文件共享的选项。首选的文件格式是图像文件（.jpg或.png）和文本文件。但我无法做到。我尝试使用html的input标记，但它没有将任何文件上传到服务器。

这是我的服务器端代码（server.js）

var express = require("express")
  , app = express()
  , http = require("http").createServer(app)
  , bodyParser = require("body-parser")
  , io = require("socket.io").listen(app.listen(3000))
  , _ = require("underscore");
const file = require('express-fileupload');
app.use(file());

var participants = [];

app.set("ipaddr", "127.0.0.1");


app.set("port", 8080);


app.set("views", __dirname + "/views");


app.set("view engine", "jade");


app.use(express.static("public", __dirname + "/public"));


app.use(bodyParser.json());

app.get("/", function(request, response) {

  response.render("index");

});

app.post("/message", function(request, response) {

  var message = request.body.message;

  if(_.isUndefined(message) || _.isEmpty(message.trim())) {
    return response.json(400, {error: "Message is invalid"});
  }

  var name = request.body.name;

  io.sockets.emit("incomingMessage", {message: message, name: name});
  response.json(200, {message: "Message received"});

});
io.on("connection", function(socket){
  socket.on("newUser", function(data) {
    participants.push({id: data.id, name: data.name});
    io.sockets.emit("newConnection", {participants: participants});
  });
  socket.on("nameChange", function(data) {
    _.findWhere(participants, {id: socket.id}).name = data.name;
    io.sockets.emit("nameChanged", {id: data.id, name: data.name});
  });

  socket.on("disconnect", function(data) {
    participants = _.without(participants,_.findWhere(participants, {id: socket.id}));
    io.sockets.emit("userDisconnected", {id: socket.id, sender:"system"});
  });

});
http.listen(app.get("port"), app.get("ipaddr"), function() {
  console.log("Server ready. IP address: " + app.get("ipaddr") + " ..port:" + app.get("port"));
});

这是客户端代码（index.js）

function init() {
  var url = document.domain;
  var socket = io.connect(url);
  var sId = '';
  function updateParticipants(mem) {
   $('#participants').html('');
   for (var i = 0; i < mem.length; i++) {
      $('#participants').append('<span id = ' + mem[i].id + '>' +
        mem[i].name + ' ' + (mem[i].id === sId ? '(You)' : '') + '<br> </span>');
    }
  }

  socket.on('connect', function () {
    sId = socket.io.engine.id;
    console.log('Connected ' + sId);
    socket.emit('newUser', {id: sId, name: $('#name').val()});
  });

  socket.on('newConnection', function (data) {

    updateParticipants(data.participants);
    $('#messages').prepend('<br> New user joined <hr>');
  });

  socket.on('userDisconnected', function(data) {
    $('#' + data.id).remove();
  });

  socket.on('nameChanged', function (data) {
    $('#' + data.id).html(data.name + ' ' + (data.id === sId ? '(You)' : '') + '<br> ');
  });

  socket.on('incomingMessage', function (data) {
    var message = data.message;
    var name = data.name;
    $('#messages').prepend('<b>' + name + '</b><br>' + message + '<h6 style = "color: green; font-size: 11px">'+new Date().toString()+'</h6>'+'<hr>');
  });

  socket.on('error', function (reason) {
    console.log('Unable to connect to server', reason);
  });

  function sendMsg() {
    var outgoingMessage = $('#outgoingMessage').val();
    var name = $('#name').val();
    $.ajax({
      url:  '/message',
      type: 'POST',
      contentType: 'application/json',
      dataType: 'json',
      data: JSON.stringify({message: outgoingMessage, name: name})
    });
  }
  function sendAttachment(){
  	var attachment=$('#attachment').val();
  	var name = $('#name').val();
    $.ajax({
      url:  '/message',
      type: 'POST',
      contentType: 'application/json',
      dataType: 'json',
      data: JSON.stringify({message: outgoingMessage, name: name})
    });
  }
  function msgKeyDown(event) {
    if (event.which == 13) {
      event.preventDefault();
      if ($('#outgoingMessage').val().trim().length <= 0) {
        return;
      }
      sendMsg();
      $('#outgoingMessage').val('');
      var att = $('#attachment').val();

    }
  }
  function msgKeyUp() {
    var outgoingMessageValue = $('#outgoingMessage').val();
    $('#send').attr('disabled', (outgoingMessageValue.trim()).length > 0 ? false : true);
  }

  function focusName() {
    var name = $('#name').val();
    socket.emit('nameChange', {id: sId, name: name});
  }

  $('#outgoingMessage').on('keydown', msgKeyDown);
  $('#outgoingMessage').on('keyup', msgKeyUp);
  $('#name').on('focusout', focusName);
  $('#send').on('click', sendMsg);
  $('#sendFile').on('click',sendAttachment);
}

$(document).on('ready', init);

对于前端，我制作了一个Jade文件（index.jade）

doctype html
html
  head
    
    link(rel='stylesheet', href='http://fonts.googleapis.com/css?family=Open+Sans')
    link(rel='stylesheet', href='/css/style.css')   
    script(src='//code.jquery.com/jquery-1.11.0.min.js')
    script(src='/socket.io/socket.io.js')
    script(src='/js/index.js')
    title Chatroom
  body
    h1(style="color: red; text-align: center") Live ChatRoom
    div(style="color: red;")
      div.inlineBlock
        span Your name:
          input(type="text", value=" ", style="background-color: blue; color: orange; width: 300px; height:40px; font-size: 35px")#name
        br
        form#messageForm
          textarea(rows="7", cols="60", placeholder="Say something and press enter(maximum 300 characters)",maxlength=300, style ="background-color: black;color: yellow; font-size: 20px")#outgoingMessage
          br
          input(type="button", value="SEND", disabled=true, style="backround-color: purple; color:black; ")#send
      div.inlineBlock.topAligned
        b Participants
        br
        div(style = "color: gold")#participants
    div(style = "color: Yellow")#messages

有关如何在代码中进行文件共享的任何建议吗？ PS server.js中的'express-fileupload'是我尝试用于文件共享的npm包，但不起作用。

Answer 1

你是对的：

<input type="file" id="input>

这是一个示例代码，它将发送一个＆＃34;图像＆＃34;选择文件后通过WebSockets的事件。处理＆＃34;图像＆＃34;的逻辑事件应该类似于你的＆＃34; incomingMessage＆＃34;但我建议将它们分开。

document.getElementById("input").addEventListener("change", function (event) {

    // Prepeare file reader
    var file = event.target.files[0];
    var fileReader = new FileReader();

    fileReader.onloadend = function (event) {
      var image = event.target.result

      // Send an image event to the socket
      socket.emit("image", image);
    };
    // Read file
    fileReader.readAsDataURL(file);
  })

如果要显示来自WebSocket的图像，只需设置＆＃34; src＆＃34; image元素的属性：

<img src="" id="output />

侦听WebSocket事件的JavaScript：

socket.on("image", function (image) {
    output.src = image;
  });

您可以在此处找到通过WebSockets发送图像的完整示例：https://medium.com/@getflourish/from-mobile-to-desktop-cross-device-communication-using-websockets-f9c48f669c8