在.Net中推出了一个新的概念:应用程序域(AppDomain)。可以理解成很多应用程序域都可以运行在同一个.NET的进程中,可以降低系统消耗,同时不同的域之间互相隔离,在安全性方面有保障。另外对于同一个进程内不同域之间的通信也相对简单一点。
应用程序域涉及的内容很多,本文就简要描述以下两个方面:
1、如何创建、卸载域
2、如何实现域间的通信
一、如何创建、卸载域
在.NET中提供了AppDomain类为执行托管代码提供隔离、卸载和安全边界。
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AppDomainSetup info = new AppDomainSetup();
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info.LoaderOptimization = LoaderOptimization.SingleDomain;
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AppDomain domain = AppDomain.CreateDomain("MyDomain", null, info);
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domain.ExecuteAssembly("C:\\test\\DomainCom.exe");
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AppDomain.Unload(domain);
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1、使用AppDomainSetup类定义新域的属性,比如可以设置应用程序的根目录,设置被加载程序的类别。![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
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例子中使用的是SingleDomain表示加载程序不得在应用程序域之间共享内部资源,还可以使用MultiDomain、MultiDomainHost等其他属性
2、在第四行创建一个名字为MyDomain的新域
3、在第5行在新域内部执行一个应用程序
4、第6行卸载这个新域
通过这样创建后,新域的执行就算出现系统异常也不会影响到原来域的执行,那么就可以做类似WatchDog(监控子程序,一旦退出就重启)的程序了
二、如何实现域间的通信
公共语言运行库禁止在不同域中的对象之间进行直接调用,但我们可以复制这些对象,或通过代理访问这些对象
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AppDomainSetup info2 = new AppDomainSetup();
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info2.LoaderOptimization = LoaderOptimization.SingleDomain;
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info2.ApplicationBase = "C:\\test";
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AppDomain domain2 = AppDomain.CreateDomain("MyDomain2", null, info2);
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ObjectHandle objHandle = domain2.CreateInstance("DomainCom", "DomainCom.TestStatic");
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ICollection obj = objHandle.Unwrap() as ICollection;
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int i = obj.Count;
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domain2.ExecuteAssembly("C:\\test\\DomainCom.exe");
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AppDomain.Unload(domain2);
开始的代码都差不多,重点是以下几个方面:![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
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1、第5行在新域中创建一个对象(类DomainCom.TestStatic),并返回一个代理ObjectHandle 类用于在多个应用程序域之间传递对象
DomainCom.TestStatic必须从MarshalByRefObject类继承,为了演示方便,这个类很简单,从ICollection接口继承,就实现了一个Count属性:
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3、在第七在当前域中给新域中的对象赋值
4、第8行执行新域中的应用程序,这个应用程序中就是弹出一个对话框显示Count的值
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