SecurityState 类

定义

public ref class SecurityState abstract

public abstract class SecurityState

[System.Security.SecurityCritical]
public abstract class SecurityState

type SecurityState = class

[<System.Security.SecurityCritical>]
type SecurityState = class

Public MustInherit Class SecurityState

继承

Object

SecurityState

派生

System.IO.IsolatedStorage.IsolatedStorageSecurityState

属性

SecurityCriticalAttribute

示例

以下示例演示如何重写 SecurityState 类。

[SecurityCritical]
public enum WebcamSecurityOptions
{
    SafeAccess,
    FullAccess
}
[SecurityCritical]
public class WebcamSecurityState : SecurityState
{
    public WebcamSecurityState(string description, WebcamSecurityOptions options)
    {
        Options = options;
        Description = description;
    }
    public WebcamSecurityOptions Options { get; set; }
    public string Description { get; set; }
    public override void EnsureState()
    {
        if (!IsStateAvailable())
            throw new ApplicationException("WebcamSecurityState not available");
    }
}

注解

必须继承自此类，才能提供一个类，该类包含一个属性，该属性指定要执行的安全敏感操作。 SecurityState从派生类实例化的对象将传递给AppDomainManager.CheckSecuritySettings方法，以确定主机是否允许执行该操作。 方法的默认实现 CheckSecuritySettings 始终返回 false。 必须重写该方法才能检测允许的操作。

例如，如果要在库代码中访问 Web 相机，将创建一个 WebcamSecurityState 对象并调用 EnsureState 该方法来确定主机是否允许 Web 相机访问，如以下示例所示。 （可以在“示例”部分找到代码 WebcamSecurityState 。

var securityState = new WebcamSecurityState("Safe access to Webcam", WebcamSecurityOptions.SafeAccess);
try
{
    securityState.EnsureState();
    // Allocate memory.
}
catch (ApplicationException e)
{
    // Handle any exception that is thrown.
    System.Diagnostics.Debug.WriteLine(e.Message);
}

若要处理调用，AppDomainManager必须通过方法的WebcamSecurityState重写来识别AppDomainManager.CheckSecuritySettings该调用，如以下示例所示。

[SecurityCritical]
public override bool CheckSecuritySettings(System.Security.SecurityState securityState)
{
    switch (securityState.ToString())
    {
        case "WebcamSecurityState":
        {
            if ((securityState as WebcamSecurityState).Options == WebcamSecurityOptions.SafeAccess)
                return PromptUser((securityState as WebcamSecurityState).Description);
            return false;
        }
    }
    return false;
}
private bool PromptUser(string text)
{
    // Replace the OpenFileDialog with a custom user prompt.
    OpenFileDialog o = new OpenFileDialog();
    o.Title = text;
    if (o.ShowDialog() == DialogResult.OK)
        return true;
    else
        return false;
}