javascript SockJS 客户端自动重新连接？

SockJS Client auto reconnect?

提问by Alosyius

I'm trying to figure out a way for my SockJS clients to reconnect to the server if it should go down.

我试图找出一种方法，让我的 SockJS 客户端在服务器出现故障时重新连接到服务器。

I currently have this:

我目前有这个：

    new_conn = function() {    
        socket = new SockJS(protocol + serverDomain + '/echo', null, {
            'protocols_whitelist': ['websocket', 'xdr-streaming', 'xhr-streaming', 'iframe-eventsource', 'iframe-htmlfile', 'xdr-polling', 'xhr-polling', 'iframe-xhr-polling', 'jsonp-polling']
        });
    };

    socket.onopen = function () {
        clearInterval(recInterval);
    };  

    socket.onclose = function () {    
        recInterval = window.setInterval(function () {
            new_conn();
        }, 2000);
    }; 

The problem is that the setIntervalkeeps firing even after a successful reconnect. It seems that the socket.onopennever gets executed.

问题是setInterval即使成功重新连接后，它仍然会继续发射。似乎socket.onopen永远不会被执行。

Any ideas what I could be doing wrong?

任何想法我可能做错了什么？

回答by franzlorenzon

I think it could be related to variable scoping. Try this:

我认为这可能与变量范围有关。试试这个：

var recInterval = null;

new_conn = function() {    
    socket = new SockJS(protocol + serverDomain + '/echo', null, {
        'protocols_whitelist': ['websocket', 'xdr-streaming', 'xhr-streaming', 'iframe-eventsource', 'iframe-htmlfile', 'xdr-polling', 'xhr-polling', 'iframe-xhr-polling', 'jsonp-polling']
    });
};

socket.onopen = function () {
    clearInterval(recInterval);
};  

socket.onclose = function () {    
    recInterval = window.setInterval(function () {
        new_conn();
    }, 2000);
}; 

Anyway, it's strange, because you were declaring recIntervalon the windowobject, and it should have worked. If it doesn't work, you could also debug it with a browser, with debugger;statements or interactively by setting local breakpoints... (in onopen, for example).

无论如何，这很奇怪，因为您正在声明recInterval该window对象，并且它应该有效。如果它不起作用，您还可以使用浏览器，使用debugger;语句或通过设置本地断点以交互方式调试它......（onopen例如，in ）。

By the way, I rewrited the whole code like this (I like refactoring:):

顺便说一句，我把整个代码改写成这样（我喜欢重构：）：

var recInterval = null;
var socket = null;

var new_conn = function() {    
    socket = new SockJS(protocol + serverDomain + '/echo', null, {
        'protocols_whitelist': ['websocket', 'xdr-streaming', 'xhr-streaming', 
                                'iframe-eventsource', 'iframe-htmlfile', 
                                'xdr-polling', 'xhr-polling', 'iframe-xhr-polling',
                                'jsonp-polling']
    });

    socket.onopen = function () {
        clearInterval(recInterval);
    };  

    socket.onclose = function () {    
        recInterval = setInterval(function () {
            new_conn();
        }, 2000);
    };
};

回答by daPhantom

In case anyone still interested in this topic: The refactored code snippet from franzlorenzon causes a lot of reconnects since it is kind of recursive reconnecting itself somehow since each two seconds a new onclose event is spawned (regardless of the recInterval).

如果有人仍然对这个主题感兴趣：来自 franzlorenzon 的重构代码片段会导致大量重新连接，因为它是一种递归重新连接自身，因为每两秒会产生一个新的 onclose 事件（无论 recInterval 是多少）。

Moving the clear interval right after the socket creation does the trick. I also added a socket = null in the onclose event.

在创建套接字后立即移动清除间隔就可以了。我还在 onclose 事件中添加了一个 socket = null 。

var recInterval = null;
var socket = null;

var new_conn = function() {
  socket = new SockJS(protocol + serverDomain + '/echo', null, {
    'protocols_whitelist': ['websocket', 'xdr-streaming', 'xhr-streaming',
      'iframe-eventsource', 'iframe-htmlfile',
      'xdr-polling', 'xhr-polling', 'iframe-xhr-polling',
      'jsonp-polling'
    ]
  });

  clearInterval(recInterval);

  socket.onopen = function() {

  };

  socket.onclose = function() {
    socket = null;
    recInterval = setInterval(function() {
      new_conn();
    }, 2000);
  };
};