请问Page.LoadControl("abc.ascx"); 这个Page.LoadControl具体在做什么动作？我知道是加载控件，不过这个加载具体是怎么个过程？

Question

ascx用户控件。

Answer 1

  当你激发一个服务器控件的事件时，它动态加载，可以先在放一个 placeholder 
  usercontrol  col=(usercontrol )this.page.loadcontrol(yourcontrol.ascx)
  palceholder.control.add(col);
这样就加载了  
 

Answer 2

to:ab83328523不是说这个。而是问Page到底在做什么。为什么要LoadControl，直接Controls.Add为什么不行。

Answer 3

说起来就是通过制定的路径,创建控件的实例反编译下,两个相关函数:
private BuildResult GetVPathBuildResultInternal(VirtualPath virtualPath, bool noBuild, bool allowCrossApp, bool allowBuildInPrecompile)
{
    if (this._compilationStage == CompilationStage.TopLevelFiles)
    {
        throw new HttpException(SR.GetString("Too_early_for_webfile", new object[] { virtualPath }));
    }
    BuildResult vPathBuildResultFromCacheInternal = this.GetVPathBuildResultFromCacheInternal(virtualPath);
    if (vPathBuildResultFromCacheInternal == null)
    {
        if (noBuild)
        {
            return null;
        }
        this.ValidateVirtualPathInternal(virtualPath, allowCrossApp, false);
        Util.CheckVirtualFileExists(virtualPath);
        if (this.IsNonUpdatablePrecompiledApp && !allowBuildInPrecompile)
        {
            throw new HttpException(SR.GetString("Cant_update_precompiled_app", new object[] { virtualPath }));
        }
        bool gotLock = false;
        try
        {
            CompilationLock.GetLock(ref gotLock);
            vPathBuildResultFromCacheInternal = this.GetVPathBuildResultFromCacheInternal(virtualPath);
            if (vPathBuildResultFromCacheInternal != null)
            {
                return vPathBuildResultFromCacheInternal;
            }
            VirtualPathSet data = CallContext.GetData("CircRefChk") as VirtualPathSet;
            if (data == null)
            {
                data = new VirtualPathSet();
                CallContext.SetData("CircRefChk", data);
            }
            if (data.Contains(virtualPath))
            {
                throw new HttpException(SR.GetString("Circular_include"));
            }
            data.Add(virtualPath);
            try
            {
                this.EnsureTopLevelFilesCompiled();
                return this.CompileWebFile(virtualPath);
            }
            finally
            {
                data.Remove(virtualPath);
            }
        }
        finally
        {
            if (gotLock)
            {
                CompilationLock.ReleaseLock();
            }
        }
    }
    return vPathBuildResultFromCacheInternal;
} 
private Control LoadControl(IWebObjectFactory objectFactory, VirtualPath virtualPath, Type t, object[] parameters)
{
    BuildResultCompiledType type = null;
    BuildResultNoCompileUserControl control = null;
    PartialCachingAttribute cachingAttribute;
    if (objectFactory != null)
    {
        type = objectFactory as BuildResultCompiledType;
        if (type != null)
        {
            t = type.ResultType;
            Util.CheckAssignableType(typeof(UserControl), t);
        }
        else
        {
            control = (BuildResultNoCompileUserControl) objectFactory;
        }
    }
    else if (t != null)
    {
        Util.CheckAssignableType(typeof(Control), t);
    }
    if (t != null)
    {
        cachingAttribute = (PartialCachingAttribute) TypeDescriptor.GetAttributes(t)[typeof(PartialCachingAttribute)];
    }
    else
    {
        cachingAttribute = control.CachingAttribute;
    }
    if (cachingAttribute == null)
    {
        Control control2;
        if (objectFactory != null)
        {
            control2 = (Control) objectFactory.CreateInstance();
        }
        else
        {
            control2 = (Control) HttpRuntime.CreatePublicInstance(t, parameters);
        }
        UserControl control3 = control2 as UserControl;
        if (control3 != null)
        {
            if (virtualPath != null)
            {
                control3.TemplateControlVirtualPath = virtualPath;
            }
            control3.InitializeAsUserControl(this.Page);
        }
        return control2;
    }
    HashCodeCombiner combinedHashCode = new HashCodeCombiner();
    if (objectFactory != null)
    {
        combinedHashCode.AddObject(objectFactory);
    }
    else
    {
        combinedHashCode.AddObject(t);
    }
    if (!cachingAttribute.Shared)
    {
        this.AddStackContextToHashCode(combinedHashCode);
    }
    string combinedHashString = combinedHashCode.CombinedHashString;
    return new PartialCachingControl(objectFactory, t, cachingAttribute, "_" + combinedHashString, parameters);
}