問題描述

我在碼頭服務器上執行了一段 javascript，該服務器正在向另一臺服務器(wamp 服務器)上的 scoket 發送 XMLHTTPRequest.請求被發送到套接字，但是 XHR 響應似乎被阻塞了.

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.

我聽說我可以使用 JSONP 來解決這個問題.但是，由于我對 javascript 都很陌生，而且我從未使用過 JSONP 技術，在此之前我非常感謝有關如何使用這種技術的任何幫助?

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，因為當我檢查服務器日志時，我在 get 請求中得到 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 技術使用完全不同的機制向服務器發出 HTTP 請求并根據響應進行操作.它需要客戶端頁面和服務器上的協作代碼.服務器必須有一個 URL 來響應 HTTPGET"請求，其中包含一個包裹在函數調用中的 JSON 塊.因此，您不能只對任何舊服務器進行 JSONP 事務；它必須是明確提供該功能的服務器.

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.

這個想法是您的客戶端代碼動態創建一個