IPermission 介面

定義

命名空間:

System.Security

組件:

netstandard.dll, System.Runtime.dll

警告

Code Access Security is not supported or honored by the runtime.

定義由使用權限類型實作的方法。

C#

[System.Obsolete("Code Access Security is not supported or honored by the runtime.", DiagnosticId="SYSLIB0003", UrlFormat="https://aka.ms/dotnet-warnings/{0}")]
public interface IPermission : System.Security.ISecurityEncodable

衍生

System.IdentityModel.Services.ClaimsPrincipalPermission

System.Security.CodeAccessPermission

System.Security.Permissions.PrincipalPermission

屬性

ObsoleteAttribute

實作

ISecurityEncodable

範例

此範例示範如何定義許可權類別，以搭配程式代碼存取安全性使用。 會實作所有必要的許可權介面。

C#

using System;
using System.Security;
using System.Security.Permissions;
using System.Reflection;

// Enumerated type for permission states.
[Serializable]
public enum SoundPermissionState
{
    NoSound = 0,
    PlaySystemSounds = 1,
    PlayAnySound = 2
}

// Derive from CodeAccessPermission to gain implementations of the following
// sealed IStackWalk methods: Assert, Demand, Deny, and PermitOnly.
// Implement the following abstract IPermission methods: Copy, Intersect, and IsSubSetOf.
// Implementing the Union method of the IPermission class is optional.
// Implement the following abstract ISecurityEncodable methods: FromXml and ToXml.
// Making the class 'sealed' is optional.

public sealed class SoundPermission : CodeAccessPermission, IPermission,
    IUnrestrictedPermission, ISecurityEncodable, ICloneable
{
    private Boolean m_specifiedAsUnrestricted = false;
    private SoundPermissionState m_flags = SoundPermissionState.NoSound;

    // This constructor creates and initializes a permission with generic access.
    public SoundPermission(PermissionState state)
    {
        m_specifiedAsUnrestricted = (state == PermissionState.Unrestricted);
    }

    // This constructor creates and initializes a permission with specific access.
    public SoundPermission(SoundPermissionState flags)
    {
        if (!Enum.IsDefined(typeof(SoundPermissionState), flags))
            throw new ArgumentException
                ("flags value is not valid for the SoundPermissionState enuemrated type");
        m_specifiedAsUnrestricted = false;
        m_flags = flags;
    }

    // For debugging, return the state of this object as XML.
    public override String ToString() { return ToXml().ToString(); }

    // Private method to cast (if possible) an IPermission to the type.
    private SoundPermission VerifyTypeMatch(IPermission target)
    {
        if (GetType() != target.GetType())
            throw new ArgumentException(String.Format("target must be of the {0} type",
                GetType().FullName));
        return (SoundPermission)target;
    }

    // This is the Private Clone helper method.
    private SoundPermission Clone(Boolean specifiedAsUnrestricted, SoundPermissionState flags)
    {
        SoundPermission soundPerm = (SoundPermission)Clone();
        soundPerm.m_specifiedAsUnrestricted = specifiedAsUnrestricted;
        soundPerm.m_flags = specifiedAsUnrestricted ? SoundPermissionState.PlayAnySound : m_flags;
        return soundPerm;
    }

    #region IPermission Members
    // Return a new object that contains the intersection of 'this' and 'target'.
    public override IPermission Intersect(IPermission target)
    {
        // If 'target' is null, return null.
        if (target == null) return null;

        // Both objects must be the same type.
        SoundPermission soundPerm = VerifyTypeMatch(target);

        // If 'this' and 'target' are unrestricted, return a new unrestricted permission.
        if (m_specifiedAsUnrestricted && soundPerm.m_specifiedAsUnrestricted)
            return Clone(true, SoundPermissionState.PlayAnySound);

        // Calculate the intersected permissions. If there are none, return null.
        SoundPermissionState val = (SoundPermissionState)
            Math.Min((Int32)m_flags, (Int32)soundPerm.m_flags);
        if (val == 0) return null;

        // Return a new object with the intersected permission value.
        return Clone(false, val);
    }

    // Called by the Demand method: returns true if 'this' is a subset of 'target'.
    public override Boolean IsSubsetOf(IPermission target)
    {
        // If 'target' is null and this permission allows nothing, return true.
        if (target == null) return m_flags == 0;

        // Both objects must be the same type.
        SoundPermission soundPerm = VerifyTypeMatch(target);

        // Return true if the permissions of 'this' is a subset of 'target'.
        return m_flags <= soundPerm.m_flags;
    }

    // Return a new object that matches 'this' object's permissions.
    public sealed override IPermission Copy()
    {
        return (IPermission)Clone();
    }

    // Return a new object that contains the union of 'this' and 'target'.
    // Note: You do not have to implement this method. If you do not, the version
    // in CodeAccessPermission does this:
    //    1. If target is not null, a NotSupportedException is thrown.
    //    2. If target is null, then Copy is called and the new object is returned.
    public override IPermission Union(IPermission target)
    {
        // If 'target' is null, then return a copy of 'this'.
        if (target == null) return Copy();

        // Both objects must be the same type.
        SoundPermission soundPerm = VerifyTypeMatch(target);

        // If 'this' or 'target' are unrestricted, return a new unrestricted permission.
        if (m_specifiedAsUnrestricted || soundPerm.m_specifiedAsUnrestricted)
            return Clone(true, SoundPermissionState.PlayAnySound);

        // Return a new object with the calculated, unioned permission value.
        return Clone(false, (SoundPermissionState)
            Math.Max((Int32)m_flags, (Int32)soundPerm.m_flags));
    }
    #endregion

    #region ISecurityEncodable Members
    // Populate the permission's fields from XML.
    public override void FromXml(SecurityElement e)
    {
        m_specifiedAsUnrestricted = false;
        m_flags = 0;

        // If XML indicates an unrestricted permission, make this permission unrestricted.
        String s = (String)e.Attributes["Unrestricted"];
        if (s != null)
        {
            m_specifiedAsUnrestricted = Convert.ToBoolean(s);
            if (m_specifiedAsUnrestricted)
                m_flags = SoundPermissionState.PlayAnySound;
        }

        // If XML indicates a restricted permission, parse the flags.
        if (!m_specifiedAsUnrestricted)
        {
            s = (String)e.Attributes["Flags"];
            if (s != null)
            {
                m_flags = (SoundPermissionState)
                Convert.ToInt32(Enum.Parse(typeof(SoundPermission), s, true));
            }
        }
    }

    // Produce XML from the permission's fields.
    public override SecurityElement ToXml()
    {
        // These first three lines create an element with the required format.
        SecurityElement e = new SecurityElement("IPermission");
        // Replace the double quotation marks ("") with single quotation marks ('')
        // to remain XML compliant when the culture is not neutral.
        e.AddAttribute("class", GetType().AssemblyQualifiedName.Replace('\"', '\''));
        e.AddAttribute("version", "1");

        if (!m_specifiedAsUnrestricted)
            e.AddAttribute("Flags", Enum.Format(typeof(SoundPermissionState), m_flags, "G"));
        else
            e.AddAttribute("Unrestricted", "true");
        return e;
    }
    #endregion

    #region IUnrestrictedPermission Members
    // Returns true if permission is effectively unrestricted.
    public Boolean IsUnrestricted()
    {
        // This means that the object is unrestricted at runtime.
        return m_flags == SoundPermissionState.PlayAnySound;
    }
    #endregion

    #region ICloneable Members

    // Return a copy of the permission.
    public Object Clone() { return MemberwiseClone(); }

    #endregion
}

備註

注意

程式代碼啟用安全性 (CAS) 在所有版本的 .NET Framework 和 .NET 中已被取代。 最新版本的 .NET 不接受 CAS 批注，並在使用 CAS 相關 API 時產生錯誤。 開發人員應尋求替代方案來完成安全性工作。

Common Language Runtime 中的許可權是描述可針對指定資源保護之作業集的物件。 許可權物件描述受安全性控制約束的作業或存取權;它不代表執行作業的存取權或許可權。 應用程式程式代碼和 .NET Framework 安全性系統會以下列方式使用許可權：

• 程序代碼會要求其執行所需的許可權。

• 安全系統原則會將許可權授與程序代碼，以便執行。

• 程序代碼要求呼叫程式代碼具有許可權。

• 程序代碼會使用判斷提示/拒絕/僅允許覆寫安全性堆疊。

備註

如果您撰寫新的許可權，則必須在 類別中實作此介面。

重要

多個線程可以存取許可權。 實作此介面時，您必須保證 IsSubsetOf、 Intersect、 Union和 Copy 方法實作是安全線程。

方法

Copy()	已淘汰. 建立並傳回目前權限的相同複本。
Demand()	已淘汰. 如果不符合安全性要求，在 Run Time 時會擲回 SecurityException。
FromXml(SecurityElement)	已淘汰. 透過 XML 編碼，重新建構具有指定狀態的安全性物件。 (繼承來源 ISecurityEncodable)
Intersect(IPermission)	已淘汰. 建立並傳回目前權限與指定權限交集的權限。
IsSubsetOf(IPermission)	已淘汰. 判斷目前權限是否為指定權限的子集。
ToXml()	已淘汰. 建立安全物件及其目前狀態的 XML 編碼方式。 (繼承來源 ISecurityEncodable)
Union(IPermission)	已淘汰. 建立目前權限與指定權限聯集的權限。

適用於