Mvc系统学习7—Action的选择过程

public override ActionDescriptor FindAction(ControllerContext controllerContext, string actionName) {
            if (controllerContext == null) {
                throw new ArgumentNullException("controllerContext");
            }
            if (String.IsNullOrEmpty(actionName)) {
                throw new ArgumentException(MvcResources.Common_NullOrEmpty, "actionName");
            }
            //TODO:获取相应的描述action
             MethodInfo matched = _selector.FindActionMethod(controllerContext, actionName);
            if (matched == null) {
                return null;
            }

            return new ReflectedActionDescriptor(matched, actionName, this);
        }

public MethodInfo FindActionMethod(ControllerContext controllerContext, string actionName) {
            //获取别名匹配的方法
             List<MethodInfo> methodsMatchingName = GetMatchingAliasedMethods(controllerContext, actionName);
            //将没有别名的方法和别名匹配的方法添加到一起
             methodsMatchingName.AddRange(NonAliasedMethods[actionName]);
            //实现方法的筛选
             List<MethodInfo> finalMethods = RunSelectionFilters(controllerContext, methodsMatchingName);

            switch (finalMethods.Count) {
                case 0:
                    return null;

                case 1:
                    return finalMethods[0];

                default://如果找到的方法个数大于1，则抛出异常：方法之间存在不明确调用
                    throw CreateAmbiguousMatchException(finalMethods, actionName);
            }
        }

internal List<MethodInfo> GetMatchingAliasedMethods(ControllerContext controllerContext, string actionName) {
            // find all aliased methods which are opting in to this request
            // to opt in, all attributes defined on the method must return true
            //注意下面的AliasedMethods
            var methods = from methodInfo in AliasedMethods
                          let attrs = (ActionNameSelectorAttribute[])methodInfo.GetCustomAttributes(typeof(ActionNameSelectorAttribute), true /* inherit */)
                          where attrs.All(attr => attr.IsValidName(controllerContext, actionName, methodInfo))
                          select methodInfo;
            
            return methods.ToList();
        }

private void PopulateLookupTables() {
            //获取Controller下面的所有Action
            MethodInfo[] allMethods = ControllerType.GetMethods(BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.Public);
            //获取有效的方法IsValidActionMethod是一个Predicate委托，为什么还要在这里过滤一次还不是很明白
            MethodInfo[] actionMethods = Array.FindAll(allMethods, IsValidActionMethod);
            //获取定义有别名的函数，也就是方法的特性有ActionNameSelectorAttribute或者ActionNameSelectorAttribute的子类
            //IsMethodDecoratedWithAliasingAttribute也是一个Predicate委托,代码：
            //return methodInfo.IsDefined(typeof(ActionNameSelectorAttribute), true /* inherit */);
            AliasedMethods = Array.FindAll(actionMethods, IsMethodDecoratedWithAliasingAttribute);
            //获取没有别名的函数，
            NonAliasedMethods = actionMethods.Except(AliasedMethods).ToLookup(method => method.Name, StringComparer.OrdinalIgnoreCase);
        }

private static List<MethodInfo> RunSelectionFilters(ControllerContext controllerContext, List<MethodInfo> methodInfos) {
            // remove all methods which are opting out of this request
            // to opt out, at least one attribute defined on the method must return false

            List<MethodInfo> matchesWithSelectionAttributes = new List<MethodInfo>();
            List<MethodInfo> matchesWithoutSelectionAttributes = new List<MethodInfo>();

            foreach (MethodInfo methodInfo in methodInfos) {
                ActionMethodSelectorAttribute[] attrs = (ActionMethodSelectorAttribute[])methodInfo.GetCustomAttributes(typeof(ActionMethodSelectorAttribute), true /* inherit */);
                if (attrs.Length == 0) {
                    matchesWithoutSelectionAttributes.Add(methodInfo);
                }
                //attr.IsValidForRequest判断是否有添加HttpPost或者HttpGet特性
                else if (attrs.All(attr => attr.IsValidForRequest(controllerContext, methodInfo))) {
                    matchesWithSelectionAttributes.Add(methodInfo);
                }
            }

[AttributeUsage(AttributeTargets.Method, Inherited = true, AllowMultiple = false)]
    public class MulSubmitActionAttribute : ActionNameSelectorAttribute
    {
        private string _submitBtnName;

        public MulSubmitActionAttribute(string submitBtnName)
        {
            if (String.IsNullOrEmpty(submitBtnName))
            {
                throw new ArgumentException("参数不能为空", "submitBtnName");
            }
            this._submitBtnName = submitBtnName;
           
        }

        public override bool IsValidName(ControllerContext controllerContext, string actionName, System.Reflection.MethodInfo methodInfo)
        {
            if (this._submitBtnName=="changehandler")//当是changehandler这个按钮提交时就返回真
            {
                return controllerContext.HttpContext.Request[this._submitBtnName] != null;     
            }
            //其他按钮提交也返回真，错误就在这里，这就造成了这个函数的返回永远是真              //这里返回false才是正确的,而且TestAction上面不用加MulSubmitActionAttribute
            return true;
        }
    }

[HttpGet]
        public ActionResult Index()
        {
            ViewData["Message"] = "欢迎使用 ASP.NET MVC!";
            return View();
        }
 
        [MulSubmitActionAttribute("other")]
        public ActionResult TestAction(Person person)
        {
            return View();
        }

        [MulSubmitActionAttribute("changehandler")]
        public ActionResult ChangeHandler(Person person)
        {
            return View("ChangeHandler"); 
        }

1  <form action="Index" method="post">
2            <%=Html.EditorForModel()%>
3            <input type="submit"  value="提交" name="tijiao" />
4            <input type="submit" value="更改经纪人" name="changehandler" />
5           </form>