具体实现步骤如下:
一、开发web用户控件
这一步和以前的开发没有区别。
1、首先新建一个web应用程序(需要VS2005 sp1支持)
2、然后在里面开发几个web用户控件
3、在ascx文件上右键-〉属性-〉生成操作选择嵌入的资源
4、生成dll就可以了(dll的名字为:Test.Control.dll,后面会用到)
二、开发一个虚拟文件系统提供类
这一步是最重要的一步。
具体思路就是:在系统中注册这个类,然后在每访问一个文件/资源的时候会自动调用这个类,在这个类中判断文件的路径是否是我们定义的,如果是就用我们的逻辑来处理,即从dll中取出资源。
首先把类的代码贴出来,我想可能许多人应该和我一样,喜欢直接先看代码:)
DllVirtualPathProvider
public class DllVirtualPathProvider : System.Web.Hosting.VirtualPathProvider
{
public DllVirtualPathProvider()
{
}
public override string CombineVirtualPaths(string basePath, string relativePath)
{
if (IsAppResourcePath(basePath))
{
return null;
}
return Previous.CombineVirtualPaths(basePath, relativePath);
}
public override System.Runtime.Remoting.ObjRef CreateObjRef(Type requestedType)
{
return Previous.CreateObjRef(requestedType);
}
public override bool DirectoryExists(string virtualDir)
{
if (IsAppResourcePath(virtualDir))
{
return true;
}
else
{
return Previous.DirectoryExists(virtualDir);
}
}
public override string GetCacheKey(string virtualPath)
{
if (IsAppResourcePath(virtualPath))
{
return null;
}
else
{
return Previous.GetCacheKey(virtualPath);
}
}
public override string GetFileHash(string virtualPath, IEnumerable virtualPathDependencies)
{
if (IsAppResourcePath(virtualPath))
{
return null;
}
else
{
return Previous.GetFileHash(virtualPath, virtualPathDependencies);
}
}
private bool IsAppResourcePath(string virtualPath)
{
String checkPath = VirtualPathUtility.ToAppRelative(virtualPath);
return checkPath.StartsWith("~/MyUserControl/Test.Control.dll/", StringComparison.InvariantCultureIgnoreCase);
}
public override bool FileExists(string virtualPath)
{
return (IsAppResourcePath(virtualPath) || Previous.FileExists(virtualPath));
}
public override VirtualFile GetFile(string virtualPath)
{
if (IsAppResourcePath(virtualPath))
{
return new AssemblyResourceVirtualFile(virtualPath);
}
else
{
return Previous.GetFile(virtualPath);
}
}
public override System.Web.Caching.CacheDependency GetCacheDependency(string virtualPath,
System.Collections.IEnumerable virtualPathDependencies, DateTime utcStart)
{
if (IsAppResourcePath(virtualPath))
{
string path = HttpRuntime.AppDomainAppPath + virtualPath.Substring(1);
return new System.Web.Caching.CacheDependency(path);
}
else
{
return Previous.GetCacheDependency(virtualPath, virtualPathDependencies, utcStart);
}
}
}
重点有以下几个:public class DllVirtualPathProvider : System.Web.Hosting.VirtualPathProvider
{
public DllVirtualPathProvider()
{
}
public override string CombineVirtualPaths(string basePath, string relativePath)
{
if (IsAppResourcePath(basePath))
{
return null;
}
return Previous.CombineVirtualPaths(basePath, relativePath);
}
public override System.Runtime.Remoting.ObjRef CreateObjRef(Type requestedType)
{
return Previous.CreateObjRef(requestedType);
}
public override bool DirectoryExists(string virtualDir)
{
if (IsAppResourcePath(virtualDir))
{
return true;
}
else
{
return Previous.DirectoryExists(virtualDir);
}
}
public override string GetCacheKey(string virtualPath)
{
if (IsAppResourcePath(virtualPath))
{
return null;
}
else
{
return Previous.GetCacheKey(virtualPath);
}
}
public override string GetFileHash(string virtualPath, IEnumerable virtualPathDependencies)
{
if (IsAppResourcePath(virtualPath))
{
return null;
}
else
{
return Previous.GetFileHash(virtualPath, virtualPathDependencies);
}
}
private bool IsAppResourcePath(string virtualPath)
{
String checkPath = VirtualPathUtility.ToAppRelative(virtualPath);
return checkPath.StartsWith("~/MyUserControl/Test.Control.dll/", StringComparison.InvariantCultureIgnoreCase);
}
public override bool FileExists(string virtualPath)
{
return (IsAppResourcePath(virtualPath) || Previous.FileExists(virtualPath));
}
public override VirtualFile GetFile(string virtualPath)
{
if (IsAppResourcePath(virtualPath))
{
return new AssemblyResourceVirtualFile(virtualPath);
}
else
{
return Previous.GetFile(virtualPath);
}
}
public override System.Web.Caching.CacheDependency GetCacheDependency(string virtualPath,
System.Collections.IEnumerable virtualPathDependencies, DateTime utcStart)
{
if (IsAppResourcePath(virtualPath))
{
string path = HttpRuntime.AppDomainAppPath + virtualPath.Substring(1);
return new System.Web.Caching.CacheDependency(path);
}
else
{
return Previous.GetCacheDependency(virtualPath, virtualPathDependencies, utcStart);
}
}
}
1、必须从VirtualPathProvider类继承
2、IsAppResourcePath方法是用来判断是否为我们定义的路径格式:~/MyUserControl/Test.Control.dll/,下面调用的时候就使用这个路径
3、注意GetCacheKey方法:
public override string GetCacheKey(string virtualPath)
{
if (IsAppResourcePath(virtualPath))
{
return null;
}
else
{
return Previous.GetCacheKey(virtualPath);
}
}
这里当符合条件时一定要返回null,如果返回"",会导致所有的用户控件都使用一个key值,从而所有的用户控件都显示同样的内容了。如果返回其他非空字符,会报异常(它会去查找cache,我们是没有的){
if (IsAppResourcePath(virtualPath))
{
return null;
}
else
{
return Previous.GetCacheKey(virtualPath);
}
}
另外所有的方法当不符合我们的条件时一定要调用 Previous.**** 因为系统中可能有多个虚拟文件提供程序的。
4、GetCacheDependency方法:
if (IsAppResourcePath(virtualPath))
{
string path = HttpRuntime.AppDomainAppPath + virtualPath.Substring(1);
return new System.Web.Caching.CacheDependency(path);
}
这个方法是用来决定Cache的使用的,如果返回null,会导致性能严重下降,每次调用用户控件时都会重新编译,这里返回的当前路径(需要在网站目录下再建立子目录:MyUserControl\Test.Control.dll),这个目录下是空的,这样当每次取Cache时都会认为我们的ascx没有修改,不需要重新编译。{
string path = HttpRuntime.AppDomainAppPath + virtualPath.Substring(1);
return new System.Web.Caching.CacheDependency(path);
}
5、在GetFile方法中我们返回的是一个AssemblyResourceVirtualFile类:
class AssemblyResourceVirtualFile : VirtualFile
{
string path;
public AssemblyResourceVirtualFile(string virtualPath)
: base(virtualPath)
{
path = VirtualPathUtility.ToAppRelative(virtualPath);
}
public override System.IO.Stream Open()
{
string[] parts = path.Split('/');
string assemblyName = parts[2];
string resourceName = parts[3];
assemblyName = Path.Combine(HttpRuntime.BinDirectory, assemblyName);
System.Reflection.Assembly assembly = System.Reflection.Assembly.LoadFrom(assemblyName);
if (assembly != null)
{
return assembly.GetManifestResourceStream(resourceName);
}
return null;
}
}
这个类的目的就是从我们的dll中读出资源文件。{
string path;
public AssemblyResourceVirtualFile(string virtualPath)
: base(virtualPath)
{
path = VirtualPathUtility.ToAppRelative(virtualPath);
}
public override System.IO.Stream Open()
{
string[] parts = path.Split('/');
string assemblyName = parts[2];
string resourceName = parts[3];
assemblyName = Path.Combine(HttpRuntime.BinDirectory, assemblyName);
System.Reflection.Assembly assembly = System.Reflection.Assembly.LoadFrom(assemblyName);
if (assembly != null)
{
return assembly.GetManifestResourceStream(resourceName);
}
return null;
}
}
三、注册这个虚拟文件提供程序
这一个很简单,在global.asax中注册:
protected void Application_Start(object sender, EventArgs e)
{
System.Web.Hosting.HostingEnvironment.RegisterVirtualPathProvider(new DllVirtualPathProvider());
}
{
System.Web.Hosting.HostingEnvironment.RegisterVirtualPathProvider(new DllVirtualPathProvider());
}
四、调用dll中的用户控件
Control control1 = this.LoadControl("/MyUserControl/Test.Control.dll/Test.Control.Sample.List.ascx");
Control control2 = this.LoadControl("/MyUserControl/Test.Control.dll/Test.Control.Sample.Sample.ascx");
form1.Controls.Add(control1);
form1.Controls.Add(control2);
比较简单,就是路径要和前面的一致。Control control2 = this.LoadControl("/MyUserControl/Test.Control.dll/Test.Control.Sample.Sample.ascx");
form1.Controls.Add(control1);
form1.Controls.Add(control2);
后记:
首先感谢 Leepy 同志认真踏实的精神,找出了我这篇文章中的一个BUG。
原来我的第四步:调用dll中的用户控件,是一个web应用程序,如果是一个web站点的话就会出现问题。因为在VS2005中调试时这两种方式呈现出来的Url是不一样的:
web应用程序:http://localhost:****/Default.aspx
web站点 :http://localhost:****/WebSite1/Default.aspx
也就是说我原来的程序没有考虑到非根目录部署的情况,针对这个BUG要修改的地方有(为了BUG的原始记录,我就不在原文中修改了,把修改点列在下面):
1、GetCacheDependency方法:
GetCacheDependency
public override System.Web.Caching.CacheDependency GetCacheDependency(string virtualPath,
System.Collections.IEnumerable virtualPathDependencies, DateTime utcStart)
{
if (IsAppResourcePath(virtualPath))
{
string path = HttpRuntime.BinDirectory;
return new System.Web.Caching.CacheDependency(path);
}
else
{
return Previous.GetCacheDependency(virtualPath, virtualPathDependencies, utcStart);
}
}
这里改成直接改成当前网站的bin目录还可以省掉建空目录的步骤了public override System.Web.Caching.CacheDependency GetCacheDependency(string virtualPath,
System.Collections.IEnumerable virtualPathDependencies, DateTime utcStart)
{
if (IsAppResourcePath(virtualPath))
{
string path = HttpRuntime.BinDirectory;
return new System.Web.Caching.CacheDependency(path);
}
else
{
return Previous.GetCacheDependency(virtualPath, virtualPathDependencies, utcStart);
}
}
2、在调用的地方修改成以下方式:
Control control1 = this.LoadControl("~/MyUserControl/MyWebApplication.dll/MyWebApplication.Sample1.ascx");
Control control2 = this.LoadControl("~/MyUserControl/MyWebApplication.dll/MyWebApplication.Sample2.ascx");
form1.Controls.Add(control1);
form1.Controls.Add(control2);
Control control2 = this.LoadControl("~/MyUserControl/MyWebApplication.dll/MyWebApplication.Sample2.ascx");
form1.Controls.Add(control1);
form1.Controls.Add(control2);