[zt]使用 AJAX 的 Sys.Net.WebRequest 从客户端请求网页-优快云博客

本文介绍如何使用MSAJAX中的Sys.Net.WebRequest进行GET和POST请求，并演示了具体的实现代码。通过创建不同的请求类型，可以灵活地与服务器交互。

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MS AJAX对JS进行了功能上的扩展，今天给大家讲述一下利用 Sys.Net.WebRequest 进行请求网页的一个例子
         新建网站，选择 ASP.NET AJAX-Enabled Web Site。
         向网站中添加一个js文件 WebRequest.js。
         添加三个全局变量：

var getPage;

var postPage;

var displayElement;

         getPage              GET方法将要请求的URL。
         postPage            POST方法将要请求的URL。
         displayElement   显示请求结果的HTML标签。

         添加初始化函数：

function pageLoad()

{

getPage = "getTarget.htm";

postPage = "postTarget.aspx";

displayElement = $get("ResultId");

}

         在这个函数中指定了默认的请求页面和用来显示结果的HTML标签。

         下面是两个主要的请求函数，代码已经加入了注释，请读者仔细阅读。
         利用Sys.Net.WebRequest()执行GET方法的函数：

function GetWebRequest()

{

alert("Performing Get Web request.");

// 实例化 WebRequest 对象.

var wRequest = new Sys.Net.WebRequest();

// 设置请求的 URL.

wRequest.set_url(getPage);

// 设置请求方法.

wRequest.set_httpVerb("GET");

// Set user's context

wRequest.set_userContext("user's context");

// 添加完成请求事件

wRequest.add_completed(OnWebRequestCompleted);

// 清楚请求结果

displayElement.innerHTML = "";

// 执行请求

wRequest.invoke();

}

利用Sys.Net.WebRequest();执行POST请求的函数：

function PostWebRequest()

{

// 实例化 WebRequest 对象.

var wRequest = new Sys.Net.WebRequest();

// 设置请求的 URL.

wRequest.set_url(postPage);

// 设置请求方法.

wRequest.set_httpVerb("POST");

var body = "Message=Hello! Do you hear me?"

wRequest.set_body(body);

wRequest.get_headers()["Content-Length"] = body.length;

// 添加完成请求事件.

wRequest.add_completed(OnWebRequestCompleted);

// 清楚请求结果

displayElement.innerHTML = "";

// 执行请求

wRequest.invoke();

}

WebRequest.js中最后完成的代码如下：

// WebRequest.js

var getPage;

var postPage;

var displayElement;

function pageLoad()

{

getPage = "getTarget.htm";

postPage = "postTarget.aspx";

displayElement = $get("ResultId");

}

// 利用GET方法执行请求。

// 注意GET请求的参数包含在指定URL的查询参数中。

function GetWebRequest()

{

alert("Performing Get Web request.");

// 实例化 WebRequest 对象.

var wRequest = new Sys.Net.WebRequest();

// 设置请求的 URL.

wRequest.set_url(getPage);

// 设置请求方法.

wRequest.set_httpVerb("GET");

// Set user's context

wRequest.set_userContext("user's context");

// 添加完成请求事件

wRequest.add_completed(OnWebRequestCompleted);

// 清楚请求结果

displayElement.innerHTML = "";

// 执行请求

wRequest.invoke();

}

// 这个函数展示了如何设置请求的内容

// 函数向指定的URL执行一个POST请求，将请求信息上传到了服务器

function PostWebRequest()

{

// 实例化 WebRequest 对象.

var wRequest = new Sys.Net.WebRequest();

// 设置请求的 URL.

wRequest.set_url(postPage);

// 设置请求方法.

wRequest.set_httpVerb("POST");

var body = "Message=Hello! Do you hear me?"

wRequest.set_body(body);

wRequest.get_headers()["Content-Length"] = body.length;

// 添加完成请求事件.

wRequest.add_completed(OnWebRequestCompleted);

// 清楚请求结果

displayElement.innerHTML = "";

// 执行请求

wRequest.invoke();

}

// 获取或设置请求完成事件

function WebRequestCompleted()

{

// 实例化 WebRequest 对象.

var wRequest = new Sys.Net.WebRequest();

// 设置请求的 URL.

wRequest.set_url(getPage);

// 添加完成请求事件.

wRequest.add_completed(OnWebRequestCompleted);

alert("Added Web request completed handler");

// Remove the web request completed event handler.

// Comment the following two lines if you want to

// use the handler.

wRequest.remove_completed(OnWebRequestCompleted);

alert("Removed handler; the Web request return is not processed.");

// 执行请求

wRequest.invoke();

}

// 获取请求的URL

function GetWebRequestResolvedUrl()

{

// Instantiate the WebRequest.

var wRequest = new Sys.Net.WebRequest();

// 设置请求的 URL.

wRequest.set_url(getPage);

// 添加完成请求事件.

var resUrl = wRequest.getResolvedUrl();

alert("Resolved Url: " + resUrl);

// 添加完成请求事件.

wRequest.add_completed(OnWebRequestCompleted);

// 执行请求

wRequest.invoke();

}

// 获取并设置请求的超时时间

function WebRequestTimeout()

{

// 实例化 WebRequest 对象.

var wRequest = new Sys.Net.WebRequest();

// 设置请求的 URL.

wRequest.set_url(getPage);

var defaultTimeout =

wRequest.get_timeout();

// 设置请求超时时间为 100 毫秒.

wRequest.set_timeout(100);

var newTimeout =

wRequest.get_timeout();

alert("Default timeout: " + defaultTimeout);

alert("New timeout: " + newTimeout);

// 添加完成请求事件.

wRequest.add_completed(OnWebRequestCompleted);

// 执行请求

wRequest.invoke();

}

// 获取并设置请求实例.

function WebRequestExecutor()

{

// 实例化 WebRequest 对象.

var wRequest = new Sys.Net.WebRequest();

// Create the executor. In this case we just

// use the default executor. But, you can

// create a custom one.

var executor = new Sys.Net.XMLHttpExecutor();

// Set the executor.

wRequest.set_executor(executor);

// Get the current executor

var executor =

wRequest.get_executor();

alert("Response availabe: " + executor.get_responseAvailable())

}

// 获取并设置请求的头部

function WebRequestHeader()

{

// 实例化 WebRequest 对象.

var wRequest = new Sys.Net.WebRequest();

// 设置请求的 URL.

wRequest.set_url(postPage);

// 设置请求方法.

wRequest.set_httpVerb("POST");

var body = "Message=Hello! Do you hear me?"

wRequest.set_body(body);

// Set the header's length.

wRequest.get_headers()["Content-Length"] = body.length;

// 添加完成请求事件.

wRequest.add_completed(OnWebRequestCompletedHeader);

// 清楚请求结果

displayElement.innerHTML = "";

// 执行请求

wRequest.invoke();

}

// 请求完成的回掉函数

function OnWebRequestCompleted(executor, eventArgs)

{

if(executor.get_responseAvailable())

{

// Clear the previous results.

displayElement.innerHTML = "";

// Display Web request status.

DisplayWebRequestStatus(executor);

// Display Web request headers.

DisplayWebRequestHeaders(executor);

// Display Web request body.

DisplayWebRequestBody(executor);

}

else

{

if (executor.get_timedOut())

alert("Timed Out");

else

if (executor.get_aborted())

alert("Aborted");

}

// 显示请求头部信息的回调函数

function OnWebRequestCompletedHeader(executor, eventArgs)

{

if(executor.get_responseAvailable())

{

// Clear the previous results.

displayElement.innerHTML = "";

// Display Web request headers.

DisplayWebRequestHeaders(executor);

}

else

{

if (executor.get_timedOut())

alert("Timed Out");

else

if (executor.get_aborted())

alert("Aborted");

}

// 显示请求状态

function DisplayWebRequestStatus(executor)

{

displayElement.innerHTML +=

"Status: [" +

executor.get_statusCode() + " " +

executor.get_statusText() + "]" + "<br/>"

}

// 显示请求的头部

function DisplayWebRequestHeaders(executor)

{

displayElement.innerHTML +=

"Headers: ";

displayElement.innerHTML +=

executor.getAllResponseHeaders() + "<br/>";

}

// 显示请求的主体

function DisplayWebRequestBody(executor)

{

displayElement.innerHTML +=

"Body: ";

if (document.all)

displayElement.innerText +=

executor.get_responseData();

else

// Firefox

displayElement.textContent +=

executor.get_responseData();

}

function DisplayInformation(message)

{

// Clear the previous results.

displayElement.innerHTML = "";

// Display information.

displayElement.innerHTML = "<br/>" + message;

}

if ( typeof (Sys) !== " undefined " ) Sys.Application.notifyScriptLoaded();

         添加用以GET请求的页面getTarget.htm，代码如下：

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>无标题页</title>
</head>
<body>
<p>

        希望在以后的日子里大家多提些宝贵的意见，我会经常为大家写一些文章，有不足之处请多多指点。
        ☆聊ゾ聊☆

     </p>

</body>
</html>

         添加用以POST方法请求的测试页面postTarget.aspx：

<% @ Page Language = " C# " AutoEventWireup = " true " %>

<! DOCTYPE html PUBLIC " -//W3C//DTD XHTML 1.0 Transitional//EN " " http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd " >

< html xmlns = " http://www.w3.org/1999/xhtml " >

< head id = " Head1 " runat = " server " >

< title > Post Target </ title >

< script language = " C# " runat = " server " >

protected void Page_Load( object sender, EventArgs e)

{

if (HttpContext.Current.Request.Form["Message"] != null)

LabelID.Text =

HttpContext.Current.Request.Form["Message"].ToString();

}

</ script >

</ head >

< body >

< form id = " form1 " runat = " server " >

< div >

< h1 > WebRequestPost Target </ h1 >

< p >

< asp:Textbox id = " LabelID " Text = " test " runat = " server " />

</ p >

Yes I hear you.

</ div >

</ form >

</ body >

</ html >

最后替换Default.aspx中的代码，用来测试我们的函数吧：

<% @ Page Language = " C# " AutoEventWireup = " true " CodeFile = " Default.aspx.cs " Inherits = " _Default " %>

<! DOCTYPE html PUBLIC " -//W3C//DTD XHTML 1.0 Transitional//EN " " http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd " >

< html xmlns = " http://www.w3.org/1999/xhtml " >

< head id = " Head1 " runat = " server " >

< title > Using WebRequest </ title >

< style type = " text/css " >

body

{ font: 11pt Trebuchet MS;

font-color: #000000;

padding-top: 72px;

text-align: center }

.text

{ font: 8pt Trebuchet MS }

</ style >

</ head >

< body >

< h2 > Using WebRequest </ h2 >

< form id = " form1 " runat = " server " >

< asp:ScriptManager runat = " server " ID = " ScriptManagerId " >

< Scripts >

< asp:ScriptReference Path = " WebRequest.js " />

</ Scripts >

</ asp:ScriptManager >

</ form >

< table >

< tr align = " left " >

< td > Make GET Request: </ td >

< td >

< button id = " Button1 "

onclick = " GetWebRequest() " > GET </ button >

</ td >

</ tr >

< tr align = " left " >

< td > Request Body: </ td >

< td >

< button id = " Button2 "

onclick = " PostWebRequest() " > Body </ button >

</ td >

</ tr >

< tr align = " left " >

< td > Request Timeout: </ td >

< td >

< button id = " Button3 "

onclick = " WebRequestTimeout() " > Timeout </ button >

</ td >

</ tr >

< tr align = " left " >

< td > Request Completed Handler: </ td >

< td >

< button id = " Button4 "

onclick = " WebRequestCompleted() " > Completed Handler </ button >

</ td >

</ tr >

< tr align = " left " >

< td > Resolved Url: </ td >

< td >

< button id = " Button5 "

onclick = " GetWebRequestResolvedUrl() " > Resolved Url </ button >

</ td >

</ tr >

< tr align = " left " >

< td > Request Executor: </ td >

< td >

< button id = " Button6 "

onclick = " WebRequestExecutor() " > Executor </ button >

</ td >

</ tr >

< tr align = " left " >

< td > Request Header: </ td >

< td >

< button id = " Button7 "

onclick = " WebRequestHeader() " > Header </ button >

</ td >

</ tr >

</ table >

< hr />

< div id = " ResultId " style = " background-color:Aqua; " ></ div >

</ body >

</ html >

例子： /Files/Xuzq/dorequest.rar

转载于:https://www.cnblogs.com/Xuzq/archive/2007/01/30/634534.html