深入解析.NET 许可证编译器 (Lc.exe) 的原理与源代(2)

ResolveEventHandler handler = new ResolveEventHandler(LicenseCompiler.OnAssemblyResolve);
AppDomain.CurrentDomain.AssemblyResolve += handler;

对第一部参数分析出来的组件列表，依次循环，为它们产生授权许可

复制代码 代码如下:

DesigntimeLicenseContext creationContext = new DesigntimeLicenseContext();
foreach (string str in compLists)
{
   key = reader.ReadLine();    hashtable[key] = Type.GetType(key);        LicenseManager.CreateWithContext((Type) hashtable[key], creationContext);
}

最后，生成许可文件并保存到磁盘中，等待CSC编译器将它编译成资源文件，嵌入到程序集中。

复制代码 代码如下:

string path = null;
if (outputDir != null)
 {
    path = outputDir + @"\" + targetPE.ToLower(CultureInfo.InvariantCulture) + ".licenses";
 }
else
 {
      path = targetPE.ToLower(CultureInfo.InvariantCulture) + ".licenses";
 }
 Stream o = null;
 try
     {
            o = File.Create(path);
           DesigntimeLicenseContextSerializer.Serialize(o, targetPE.ToUpper(CultureInfo.InvariantCulture), creationContext);
     }
     finally
     {
            if (o != null)
            {
                o.Flush();
                o.Close();
            }
     }

这种方式是.NET Framework推荐的保护组件的方式，与我们平时所讨论的输入序列号，RSA签名不同。
来看一下，商业的组件是如何应用这种技术保护组件的。

复制代码 代码如下:

using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel;
namespace ComponentArt.Licensing.Providers
{
  #region RedistributableLicenseProvider
    public class RedistributableLicenseProvider : System.ComponentModel.LicenseProvider
    {
    const string strAppKey = "This edition of ComponentArt Web.UI is licensed for XYZ application only.";   

    public override System.ComponentModel.License GetLicense(LicenseContext context, Type type, object instance, bool allowExceptions)
    {
      if (context.UsageMode == LicenseUsageMode.Designtime)
      {
        // We are not going to worry about design time Issue a license
        return new ComponentArt.Licensing.Providers.RedistributableLicense(this, "The App");
      }
      else
      {
        string strFoundAppKey;
        // During runtime, we only want this control to run in the application
        // that it was packaged with.
        HttpContext ctx = HttpContext.Current;
        strFoundAppKey = (string)ctx.Application["ComponentArtWebUI_AppKey"];
        if(strAppKey == strFoundAppKey)
          return new ComponentArt.Licensing.Providers.RedistributableLicense(this, "The App");
        else
          return null;
      }
    }
  }
  #endregion
  #region RedistributableLicense Class
  public class RedistributableLicense : System.ComponentModel.License
  {
    private ComponentArt.Licensing.Providers.RedistributableLicenseProvider owner;
    private string key;
    public RedistributableLicense(ComponentArt.Licensing.Providers.RedistributableLicenseProvider owner, string key)
    {
      this.owner = owner;
      this.key = key;
    }
    public override string LicenseKey
    {
      get
      {
        return key;
      }
    }
    public override void Dispose()
    {
    }
  }
  #endregion
}

首先要创建一个类型，继承于License类型，再创建一个继承于LicenseProvider的类型，用于颁发许可证，包含在设计时许可和运行时许可，从上面的例子中可以看到，设计时没有限制，可以运行，但是到运行时，你必须有序列号，它才会生成许可对象，而不是返回null给.NET Framework类型。整个验证过程由.NET完成。
你只需要像下面这样，应用这个许可保护机制：

复制代码 代码如下: