ASP.. NET WebForms使用IoC动态加载WebUserControls
本文关键字:动态 加载 WebUserControls IoC 使用 NET WebForms ASP | 更新日期: 2023-09-27 18:08:27
我正在尝试使用IoC加载web用户控件。我使用unity,我按照书中的例子设置。到目前为止一切顺利,但当我注入看起来像单个控件本身的界面时,我就遇到了问题。我试图使用LoadControl(类型,参数),但web用户控件未加载。
我环顾网络,我找不到任何可以帮助我使用IoC动态加载web用户控件的东西。
你们有其他的加载策略吗?你需要更多关于我的尝试的信息吗?
对
让你的DI容器连接你的Page, HttpHandler和UserControls在Web Forms中是绝对可能的,但是没有任何内置的东西,所以你必须自己做。有两种方法可以做到。要么创建自定义PageHandlerFactory
,要么创建自定义HttpModule
。因为唯一的方法来钩在一个PageHandlerFactory
是通过网络。配置,我的首选是使用HttpModule
。当使用HttpModule
时,您可以使用System.Web.PreApplicationStartMethodAttribute
(System. net)注册它。Web assembly)和Microsoft.Web.Infrastructure.DynamicModuleHelper.DynamicModuleUtility
(Microsoft.Web。基础设施组件)。它看起来像这样:
[assembly: System.Web.PreApplicationStartMethod(typeof(ModuleInitializer), "Init")]
public static class ModuleInitializer
{
public static void Init()
{
DynamicModuleUtility.RegisterModule(
typeof(WebFormsDependencyInjectionHttpModule));
}
}
自定义HttpModule
的技巧是挂钩到应用程序的PreRequestHandlerExecute
事件。这允许你浏览页面层次结构,并在页面执行之前注入任何依赖项。
public class WebFormsDependencyInjectionHttpModule : IHttpModule {
public static UnityContainer Container;
private HttpApplication application;
public void Init(HttpApplication context) {
this.application = context;
context.PreRequestHandlerExecute += this.PreRequestHandlerExecute;
}
public void Dispose() { }
internal static void InitializeInstance(object instance) {
Container.BuildUp(instance);
}
private void PreRequestHandlerExecute(object sender, EventArgs e) {
if (Container == null)
throw new InvalidOperationException("Set Container first.");
var handler = this.application.Context.CurrentHandler;
if (handler != null) {
InitializeHttpHandler(handler);
}
}
private void InitializeHttpHandler(IHttpHandler handler) {
InitializeInstance(handler);
if (handler is Page) {
PageInitializer.HookEventsForUserControlInitialization((Page)handler);
}
}
private sealed class PageInitializer { ... }
}
这个模块只是确保Unity的BuildUp
方法在页面生活方式的早期被调用,以建立Page
或IHttpHandler
实例。这允许您将依赖项注入到Page类中,但不会在任何使用的UserControl
实例中注入任何依赖项。为了启用这个功能,模块调用特殊的PageInitializer.HookEventsForUserControlInitialization
方法。这里的PageInitializer
类是:
internal sealed class PageInitializer {
private HashSet<Control> alreadyInitializedControls = new HashSet<Control>();
private Page page;
internal PageInitializer(Page page) {
this.page = page;
}
internal static void HookEventsForUserControlInitialization(Page page) {
var initializer = new PageInitializer(page);
page.PreInit += initializer.PreInit;
page.PreLoad += initializer.PreLoad;
}
private void PreInit(object sender, EventArgs e) {
this.RecursivelyInitializeMasterPages();
}
private void RecursivelyInitializeMasterPages() {
foreach (var masterPage in this.GetMasterPages())
this.InitializeUserControl(masterPage);
}
private IEnumerable<MasterPage> GetMasterPages() {
MasterPage master = this.page.Master;
while (master != null) {
yield return master;
master = master.Master;
}
}
private void PreLoad(object sender, EventArgs e) {
this.InitializeControlHierarchy(this.page);
}
private void InitializeControlHierarchy(Control control) {
var dataBoundControl = control as DataBoundControl;
if (dataBoundControl != null) {
dataBoundControl.DataBound += this.InitializeDataBoundControl;
} else {
var userControl = control as UserControl;
if (userControl != null)
this.InitializeUserControl(userControl);
foreach (var childControl in control.Controls.Cast<Control>()) {
this.InitializeControlHierarchy(childControl);
}
}
}
private void InitializeDataBoundControl(object sender, EventArgs e) {
var control = (DataBoundControl)sender;
if (control != null) {
control.DataBound -= this.InitializeDataBoundControl;
this.InitializeControlHierarchy(control);
}
}
private void InitializeUserControl(UserControl instance)
{
if (!this.alreadyInitializedControls.Contains(instance)) {
WebFormsDependencyInjectionHttpModule.InitializeInstance(instance);
// Ensure every user control is only initialized once.
this.alreadyInitializedControls.Add(instance);
}
}
}
PageInitializer
类将把这个过程更进一步,并将挂钩到页面的PreInit
和PreLoad
事件,以允许将依赖项注入母版页,并通过完整的控制层次结构将依赖项注入任何UserControl
。它甚至钩住控件层次结构中任何DataBoundControl
的DataBound
事件,以确保被DataBoundControl
加载的任何UserControl
都被初始化。
我想这应该能奏效:-)