如何：在使用 ASP.NET 创建的 Web 服务中管理状态

当实现 Web 服务的类派生自 WebService 类时，Web 服务可与其他 ASP.NET 应用程序访问相同的状态管理选项。 WebService 类包含许多个公共 ASP.NET 对象，包括 Session 和 Application 对象。

访问并存储特定的客户端会话所特有的状态

1. 声明一项 Web 服务。

   <%@ WebService Language="C#" Class="ServerUsage" %>
   

   <%@ WebService Language="VB" Class="ServerUsage" %>
   

2. 添加对 System.Web.Services 命名空间的引用。

   using System.Web.Services;
   

   Imports System.Web.Services
   

3. 从 WebService 派生实现 Web 服务的类。

   public class ServerUsage : WebService 
   

   Public Class ServerUsage : Inherits WebService
   

4. 声明 Web 服务方法，并将 WebMethod 属性 (Attribute) 的 EnableSession 属性 (Property) 设置为 true。

   [ WebMethod(EnableSession=true) ]
   public int PerSessionServiceUsage()
   

   < WebMethod(EnableSession:=True) > _
   Public Function PerSessionServiceUsage() As Integer
   

5. 在 Session 中存储状态，该属性为后面的检索指定状态的名称。 在下面的示例中，值 1 存储在名为 MyServiceUsage 的状态变量中。

   Session["MyServiceUsage"] = 1;
   

   Session("MyServiceUsage") = 1
   

6. 访问存储在 Session 中的状态变量。

   在下面的示例中，将访问 MyServiceUsage 状态变量以增加其值。

   Session["MyServiceUsage"] = ((int) Session["MyServiceUsage"]) + 1;
   

   Session("MyServiceUsage") = CInt(Session("MyServiceUsage")) + 1
   

访问并存储承载 Web 服务的 Web 应用程序所特有的状态

1. 声明一项 Web 服务。

   <%@ WebService Language="C#" Class="ServerUsage" %>
   

   <%@ WebService Language="VB" Class="ServerUsage" %>
   

2. 添加对 System.Web.Services 命名空间的引用。

   using System.Web.Services;
   

   Imports System.Web.Services
   

3. 从 WebService 派生实现 Web 服务的类。

   public class ServerUsage : WebService
   

   Public Class ServerUsage : Inherits WebService
   

4. 声明 Web 服务方法。

   [ WebMethod ]
   public int PerSessionServiceUsage()
   

   < WebMethod > _
   Public Function PerSessionServiceUsage() As Integer
   

5. 在 Application 中存储状态，该属性为后面的检索指定状态的名称。 在下面的示例中，值 1 存储在名为 appMyServiceUsage 的状态变量中。

   Application["appMyServiceUsage"] = 1;
   

   Application("appMyServiceUsage") = 1
   

6. 访问存储在 Application 中的状态变量。

   在下面的示例中，将访问 appMyServiceUsage 状态变量以增加其值。

   Application["appMyServiceUsage"] =
      ((int) Application["appMyServiceUsage"]) + 1;
   

   Application("appMyServiceUsage") = _
      CInt(Application("appMyServiceUsage")) + 1
   

示例

<%@ WebService Language="C#" Class="ServerUsage" %>
using System.Web.Services;

public class ServerUsage : WebService {
   [ WebMethod(Description="Number of times this service has been accessed.") ]
   public int ServiceUsage() {
     // If the Web service method hasn't been accessed,
     // initialize it to 1.
     if (Application["appMyServiceUsage"] == null) 
     {
       Application["appMyServiceUsage"] = 1;
     }
     else
     {
     // Increment the usage count.
       Application["appMyServiceUsage"] = ((int) Application["appMyServiceUsage"]) + 1;
     }
     return  (int) Application["appMyServiceUsage"];
   }

   [ WebMethod(Description="Number of times a particular client session has accessed this Web service method.",EnableSession=true) ]
   public int PerSessionServiceUsage() {
     // If the Web service method hasn't been accessed, initialize
     // it to 1.
     if (Session["MyServiceUsage"] == null) 
     {
       Session["MyServiceUsage"] = 1;
     }
     else
     {
     // Increment the usage count.
       Session["MyServiceUsage"] = ((int) Session["MyServiceUsage"]) + 1;
     }
     return  (int) Session["MyServiceUsage"];
   }
}

<%@ WebService Language="VB" Class="ServerUsage" %>
Imports System.Web.Services

Public Class ServerUsage
    Inherits WebService
    
<WebMethod(Description := "Number of times this service has been accessed.")> _
    Public Function ServiceUsage() As Integer
        ' If the Web service method hasn't been accessed, initialize
        ' it to 1.
        If Application("appMyServiceUsage") Is Nothing Then
            Application("appMyServiceUsage") = 1
        Else
            ' Increment the usage count.
            Application("appMyServiceUsage") = _
               CInt(Application("appMyServiceUsage")) + 1
        End If
        Return CInt(Application("appMyServiceUsage"))
    End Function    
    
<WebMethod(Description := "Number of times a particular client session has accessed this Web service method.", EnableSession := True)> _
    Public Function  PerSessionServiceUsage() As Integer
       ' If the Web service method hasn't been accessed,
       ' initialize it to 1.
        If Session("MyServiceUsage") Is Nothing Then
            Session("MyServiceUsage") = 1
        Else
            ' Increment the usage count.
           Session("MyServiceUsage") = CInt(Session("MyServiceUsage")) + 1
        End If
        Return CInt(Session("MyServiceUsage"))
    End Function
    
End Class

请参见

其他资源

ASP.NET State Management

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