asp.net - 如何在 asp.netweb 应用程序中显示第一个异步结果？

Question

我必须在三个类文件中发送三个异步请求，三个请求响应时间不同，第一个是 2 秒，第二个是 7 秒，第三个是 4 秒，现在我必须在 2 秒内和 2 秒后显示浏览器中的第一个响应第三个回复，最后显示第二个回复，但是现在我的结果在完成三个回复后一次显示所有回复，请给我任何建议，非常紧急，拜托.....

我的代码是

public delegate string AsyncMethodCaller(string name);
        public delegate string AsyncMethodCallertest(string name);
        public delegate string NatilusAsyn(string name);

按钮点击事件

     AsyncMethodCaller caller = new AsyncMethodCaller(ps.PennStarService);
        IAsyncResult result = caller.BeginInvoke(txtFirst.Text, null, null);
    NatilusAsyn caller123 = new NatilusAsyn(cs.PennStarService);
        IAsyncResult result123 = caller123 .BeginInvoke(txtthird.Text, null, null);
        AsyncMethodCallertest cltest = new AsyncMethodCallertest(ps.testHi);
        IAsyncResult tetsresult = cltest.BeginInvoke(txtSecond.Text, null, null);
        lblFirst.Text = caller.EndInvoke(result);           
        lblSecond.Text = cltest.EndInvoke(tetsresult);
     lblthird.Text = caller123.EndInvoke(result123);

谢谢你

score 5 · Accepted Answer

我认为问题的根源在于了解 ASP.Net 请求会发生什么。

每个页面都有其生命周期，其中包括事件管道，有关更多信息，请查看此答案。每个请求都由来自当前应用程序的 AppDomain 的工作线程处理。在页面管道完成之前，不会将响应发送给用户。

关于线程：

同时可用线程的数量可以在machine.config. 要理解的关键点是这些线程数是固定的，也就是说当达到最大并发线程数时，后续的请求会被放入一个队列中，队列中可以放入的请求数只有受服务器内存限制。

当一个工作线程调用一个耗时的操作时，您会阻塞该线程，直到操作完成，这再次意味着，如果有多个并发用户，则可能所有可用线程都可能被阻塞，从而迫使新的请求被放置在一个排队，在最坏的情况下，导致 503 错误 - 服务不可用。

防止这种情况的方法是在后台线程中调用这些方法。与您的代码类似，但在这种情况下行为不是您所期望的，您的代码正在等待线程结束以完成页面请求，这就是您同时收到结果的原因（最后的请求）。

有关异步执行 asp.net 页面的更多详细信息，请参阅这篇优秀的文章

现在为了得到你需要的结果：

（这是一个完整的工作示例，在此示例中，我使用Rx - Reactive Programming在新线程中运行耗时的方法，如果您愿意，可以将其更改为使用另一个框架，我更喜欢使用 Rx，因为我觉得对 API 更满意）

使用 PageMethods

背后的代码

    [WebMethod]
    public static string Execute1()
    {
        JavaScriptSerializer j = new JavaScriptSerializer();
        string r = string.Empty;
        var o = Observable.Start(() =>
            {
                Thread.Sleep(2000);
                r = "My Name1: " + DateTime.Now.ToString() + " Background thread: " + Thread.CurrentThread.ManagedThreadId.ToString();
            }, Scheduler.NewThread);
        o.First();
        r += " Main thread: " + Thread.CurrentThread.ManagedThreadId.ToString();
        r = j.Serialize(new { res = r });
        return r;
    }

    [WebMethod]
    public static string Execute2()
    {
        JavaScriptSerializer j = new JavaScriptSerializer();
        string r = string.Empty;
        var o = Observable.Start(() =>
        {
            Thread.Sleep(7000);
            r = "My Name2: " + DateTime.Now.ToString() + " Background thread: " + Thread.CurrentThread.ManagedThreadId.ToString();
        }, Scheduler.NewThread);
        o.First();
        r += " Main thread: " + Thread.CurrentThread.ManagedThreadId.ToString();
        r = j.Serialize(new { res = r });
        return r;
    }

    [WebMethod]
    public static string Execute3()
    {
        JavaScriptSerializer j = new JavaScriptSerializer();
        string r = string.Empty;
        var o = Observable.Start(() =>
        {
            Thread.Sleep(4000);
            r = "My Name3: " + DateTime.Now.ToString() + " Background thread: " + Thread.CurrentThread.ManagedThreadId.ToString();
        }, Scheduler.NewThread);
        o.First();
        r += " Main thread: " + Thread.CurrentThread.ManagedThreadId.ToString();
        r = j.Serialize(new { res = r });
        return r;
    }

ASPX

....
<script type="text/javascript" src="Scripts/jquery-1.7.2.min.js"></script>
....
<asp:ScriptManager runat="server" />
<input type="button" id="callAsync" name="callAsync" value="Call Async" />
<div id="first"></div>
<script type="text/javascript">
    function onsuccess1(msg) {
        var result = Sys.Serialization.JavaScriptSerializer.deserialize(msg.d);
        var h = $("#first").html();
        $("#first").html( h + "<br/>&nbsp;&nbsp;&nbsp;&nbsp;Result: " + result.res);
    }
    function onerror1(xhr) {
        alert(xhr.responseText);
    }
    function callMyMethod(url, mydata, onsuccess, onerror) {
        var h = $("#first").html();
        $("#first").html(h + "<br/>&nbsp;&nbsp;Calling Method: " + new Date());
        return $.ajax({
            cache: false,
            type: "POST",
            async: true,
            url: url,
            data: mydata, 
            contentType: "application/json",
            dataType: "json",
            success: function (msg) {
                onsuccess(msg);
            },
            error: function (xhr) {
                onerror(xhr);
            }
        });
    }
    $(document).ready(function () {
        $("#callAsync").click(function () {
            var h = $("#first").html();
            $("#first").html(h + "<br/>New call: " + new Date());
            callMyMethod("DynamicControls.aspx/Execute1", "{}", function (data) { onsuccess1(data); }, function (data) { onerror1(data); });
            callMyMethod("DynamicControls.aspx/Execute2", "{}", function (data) { onsuccess1(data); }, function (data) { onerror1(data); });
            callMyMethod("DynamicControls.aspx/Execute3", "{}", function (data) { onsuccess1(data); }, function (data) { onerror1(data); });
        });
    });
</script>

输出

此代码生成以下内容：

New call: Fri Jun 22 02:11:17 CDT 2012
  Calling Method: Fri Jun 22 02:11:17 CDT 2012
  Calling Method: Fri Jun 22 02:11:17 CDT 2012
  Calling Method: Fri Jun 22 02:11:17 CDT 2012
    Result: My Name1: 6/22/2012 2:11:19 AM Background thread: 38 Main thread: 48
    Result: My Name2: 6/22/2012 2:11:26 AM Background thread: 50 Main thread: 48
    Result: My Name3: 6/22/2012 2:11:30 AM Background thread: 52 Main thread: 48

如您所见，代码未优化，主线程被锁定，我们设置的最大秒数为 7，但在这种情况下，从调用服务器代码 (02:11:17) 到最后收到响应 (2:11:30) 13 秒过去了。这是因为 ASP.Net 默认锁定当前Session对象锁定主线程。由于我们在此示例中没有使用会话，因此我们可以像这样配置页面：

<%@ Page EnableSessionState="False"

新的输出是：

New call: Fri Jun 22 02:13:43 CDT 2012
  Calling Method: Fri Jun 22 02:13:43 CDT 2012
  Calling Method: Fri Jun 22 02:13:43 CDT 2012
  Calling Method: Fri Jun 22 02:13:43 CDT 2012
    Result: My Name1: 6/22/2012 2:13:45 AM Background thread: 52 Main thread: 26
    Result: My Name3: 6/22/2012 2:13:47 AM Background thread: 38 Main thread: 49
    Result: My Name2: 6/22/2012 2:13:50 AM Background thread: 50 Main thread: 51

现在，从第一个服务器方法调用到最后一个没有锁定主线程的响应只用了 7 秒 =)

编辑 1

如果我的理解是正确的，您需要将一些参数传递给方法并返回数据集以填充标签和文本框。

要将参数传递给 PageMethods，这是一种方法：

安装这些 Nuget 包：

命令类。此类将表示您要在 post 操作中发送到服务器方法的参数

public class ProcessXmlFilesCommand
{
    public string XmlFilePath { get; set; }

    public ProcessXmlFilesCommand()
    {
    }
}

而不是返回 a DataSet，我认为返回 a 会更容易和更易于管理IEnumerable，如下所示：

    [WebMethod]
    public static IEnumerable<MyResult> ProcessXmlFiles(ProcessXmlFilesCommand command)
    {
        List<MyResult> results = new List<MyResult>();
        var o = Observable.Start(() =>
        {
            // here do something useful, process your xml files for example
            // use the properties of the parameter command
            results.Add(new MyResult { SomethingInteresting = DateTime.Now.ToString(), FilePath = command.XmlFilePath + "Processed" });
            results.Add(new MyResult { SomethingInteresting = DateTime.Now.ToString(), FilePath = command.XmlFilePath + "Processed" });
            results.Add(new MyResult { SomethingInteresting = DateTime.Now.ToString(), FilePath = command.XmlFilePath + "Processed" });
            Thread.Sleep(2000);
        }, Scheduler.NewThread);
        o.First();
        return results.AsEnumerable();
    }

该类MyResult表示您要发送回用户的数据

public class MyResult
{
    public string SomethingInteresting { get; set; }
    public string FilePath { get; set; }
}

在您的 ASPX 页面中

<script type="text/javascript" src="Scripts/jquery-1.7.2.min.js"></script>
<script type="text/javascript" src="Scripts/json2.min.js"></script>


    <script type="text/javascript">
        function processFiles() {
            var filePath = $("#filePath").val();
            var command = new processFilesCommand(filePath);
            var jsonCommand = JSON.stringify(command);

            $.ajax({
                cache: false,
                type: "POST",
                async: true,
                url: "CustomThreads.aspx/ProcessXmlFiles",
                data: "{'command':" + jsonCommand + "}",
                contentType: "application/json; charset=utf-8",
                dataType: "json",
                success: function (msg) {
                    onFileProcessedSuccess(msg);
                },
                error: function (exc) {
                    onFileProcessedError(exc);
                }
            });
        }
        function onFileProcessedSuccess(msg) {
            var response = msg.d;
            $.each(response, function (index, myResponse) {
                $("#<%:this.myLabel.ClientID %>").append(myResponse.SomethingInteresting + "<br/>");
            });
        }
        function onFileProcessedError(exc) {
            alert("Error: " + exc.responseText);
        }
        function processFilesCommand(filePath) {
            this.XmlFilePath = filePath;
        }
        $(document).ready(function () {
            $("#processFile").click(processFiles);
        });
    </script>

<input type="text" name="filePath" id="filePath" />
<input type="button" name="processFile" id="processFile" value="Process File" />

<br /><asp:Label ID="myLabel" runat="server" />

编辑 2

这是一种简化的方式

<%@ Page EnableSessionState="False" Language="C#" AutoEventWireup="true" CodeBehind="CustomThreadsSimple.aspx.cs" Inherits="WebApplication1.CustomThreadsSimple" %>
....
<script type="text/javascript" src="Scripts/jquery-1.7.2.min.js"></script>
....
    <script type="text/javascript">
        function makeCall(url, data) {
            $("#<%:this.lblMessage.ClientID %>").append("<br/>Initializing call: " + new Date());
            $.ajax({
                url: url,
                type: "POST",
                dataType: "json",
                contentType: "application/json; charset=utf-8;",
                async: true,
                cache: false,
                data: "{name:'" + data + "'}",
                success: function (msg) {
                    $("#<%:this.lblMessage.ClientID %>").append("<br/>&nbsp;&nbsp;&nbsp;&nbsp;" + msg.d);
                },
                error: function (exc) {
                    alert(exc.responseText);
                }
            });
        }
        $(function () {
            $("#startProcess").click(function () {
                makeCall("CustomThreadsSimple.aspx/Execute1", $("#<%: this.txtData1.ClientID %>").val());
                makeCall("CustomThreadsSimple.aspx/Execute2", $("#<%: this.txtData2.ClientID %>").val());
                makeCall("CustomThreadsSimple.aspx/Execute3", $("#<%: this.txtData3.ClientID %>").val());
            });
        });
    </script>
    <asp:TextBox runat="server" ID="txtData1" />
    <asp:TextBox runat="server" ID="txtData2" />
    <asp:TextBox runat="server" ID="txtData3" />
    <input type="button" name="startProcess" id="startProcess" value="Start execution" />
    <asp:Label ID="lblMessage" runat="server" />

背后的代码

public partial class CustomThreadsSimple : System.Web.UI.Page
{
    [WebMethod]
    public static string Execute1(string name)
    {
        string res = string.Empty;
        Func<string, string> asyncMethod = x =>
        {
            Thread.Sleep(2000);
            return "Res1: " + x +" " + DateTime.Now.ToString() + " Background thread: " + Thread.CurrentThread.ManagedThreadId.ToString();
        };

        IAsyncResult asyncRes = asyncMethod.BeginInvoke(name, null, null);
        res = asyncMethod.EndInvoke(asyncRes);
        res += " Main thread: " + Thread.CurrentThread.ManagedThreadId.ToString();
        return res;
    }

    [WebMethod]
    public static string Execute2(string name)
    {
        string res = string.Empty;
        Func<string, string> asyncMethod = x =>
        {
            Thread.Sleep(7000);
            return "Res2: " + x + " " + DateTime.Now.ToString() + " Background thread: " + Thread.CurrentThread.ManagedThreadId.ToString();
        };

        IAsyncResult asyncRes = asyncMethod.BeginInvoke(name, null, null);
        res = asyncMethod.EndInvoke(asyncRes);
        res += " Main thread: " + Thread.CurrentThread.ManagedThreadId.ToString();
        return res;
    }

    [WebMethod]
    public static string Execute3(string name)
    {
        string res = string.Empty;
        Func<string, string> asyncMethod = x =>
        {
            Thread.Sleep(4000);
            return "Res3: " + x + " " + DateTime.Now.ToString() + " Background thread: " + Thread.CurrentThread.ManagedThreadId.ToString();
        };

        IAsyncResult asyncRes = asyncMethod.BeginInvoke(name, null, null);
        res = asyncMethod.EndInvoke(asyncRes);
        res += " Main thread: " + Thread.CurrentThread.ManagedThreadId.ToString();
        return res;
    }
}

输出

在此处输入图像描述

asp.net - 如何在 asp.netweb 应用程序中显示第一个异步结果？

1 回答 1

使用 PageMethods

背后的代码

ASPX

输出

编辑 1

编辑 2

Related

Reference