問(wèn)題描述

我在碼頭服務(wù)器上執(zhí)行了一段 javascript，該服務(wù)器正在向另一臺(tái)服務(wù)器(wamp 服務(wù)器)上的 scoket 發(fā)送 XMLHTTPRequest.請(qǐng)求被發(fā)送到套接字，但是 XHR 響應(yīng)似乎被阻塞了.

I have a piece of javascript executing on a jetty server which is sending a XMLHTTPRequest to a scoket on another server(wamp server). The request gets sent to the socket, however the XHR response seems to be getting blocked.

我聽(tīng)說(shuō)我可以使用 JSONP 來(lái)解決這個(gè)問(wèn)題.但是，由于我對(duì) javascript 都很陌生，而且我從未使用過(guò) JSONP 技術(shù)，在此之前我非常感謝有關(guān)如何使用這種技術(shù)的任何幫助?

I have heard that I can use JSONP to overcome this problem. However as I am new to both javascript and I have never used JSONP technique before I would greatly appreciate any help in how to use this technique?

function sendPost(url, postdata, callback) {

xmlHttp=GetXmlHttpObject()

if (xmlHttp==null) {
    alert ("Browser does not support HTTP Request")
    return
} 

xmlHttp.onreadystatechange=callback
xmlHttp.open("POST",url,true)
xmlHttp.send(postdata);

}

function sendInitRQ(width, height) {

var post = "<?xml version="1.0" encoding="UTF-8"?><command     type="init"><width>" + width + "</width><height>" + height + "</height></command>";

sendPost("http://localhost:80/socket.php", post, initReturned);

}

我知道 php 套接字正在接收帖子，因?yàn)楫?dāng)我檢查服務(wù)器日志時(shí)，我在 get 請(qǐng)求中得到 200.

I know that the php socket is recieving the post as when i check the server log i get a 200 on the get request.

我只想知道如何使用 JSONP 方法?我已經(jīng)看到了這種方法的例子，但我仍然不確定如何去做.

I just want to know how can I use the JSONP approach? I have seen exampples of the approach but Iam stilll unsure of how to do it.

推薦答案

JSONP 技術(shù)使用完全不同的機(jī)制向服務(wù)器發(fā)出 HTTP 請(qǐng)求并根據(jù)響應(yīng)進(jìn)行操作.它需要客戶(hù)端頁(yè)面和服務(wù)器上的協(xié)作代碼.服務(wù)器必須有一個(gè) URL 來(lái)響應(yīng) HTTPGET"請(qǐng)求，其中包含一個(gè)包裹在函數(shù)調(diào)用中的 JSON 塊.因此，您不能只對(duì)任何舊服務(wù)器進(jìn)行 JSONP 事務(wù)；它必須是明確提供該功能的服務(wù)器.

The JSONP technique uses a completely different mechanism for issuing HTTP requests to a server and acting on the response. It requires cooperating code in the client page and on the server. The server must have a URL that responds to HTTP "GET" requests with a block of JSON wrapped in a function call. Thus, you can't just do JSONP transactions to any old server; it must be a server that explicitly provides the functionality.

這個(gè)想法是您的客戶(hù)端代碼動(dòng)態(tài)創(chuàng)建一個(gè)