普洱茶的产地在哪,姬野爱 护士,护士献身捐精
看mvc的源码我们知道，它是在 controlleractioninvoker 类中执行 invokeaction 方法来实现过滤器和action方法执行的。
通过查看源码我们知道，他是通过调用 invokeactionmethodwithfilters 方法来实现iactionfilter过滤器和action方法执行的，如图
点进去这个方法我们可以看到
我要评论1 protected virtual actionexecutedcontext invokeactionmethodwithfilters(controllercontext controllercontext, ilist<iactionfilter> filters, actiondescriptor actiondescriptor, idictionary<string, object> parameters)
2 {
3 actionexecutingcontext precontext = new actionexecutingcontext(controllercontext, actiondescriptor, parameters);
4 func<actionexecutedcontext> seed = () => new actionexecutedcontext(controllercontext, actiondescriptor, false, null)
5 {
6 result = this.invokeactionmethod(controllercontext, actiondescriptor, parameters)
7 };
8 return filters.reverse<iactionfilter>().aggregate(seed, (func<actionexecutedcontext> next, iactionfilter filter) => () => controlleractioninvoker.invokeactionmethodfilter(filter, precontext, next))();
9 }
看到这里我直接懵逼了，由于它委托中嵌套了委托而且还简写，还调用了扩展方法aggregate累加器，所以很难直接看懂，这到底是怎么执行代码的呐？我来把代码整理如下
1 public class class1
2 {
3
4 protected virtual actionexecutedcontext invokeactionmethodwithfilters(controllercontext controllercontext, ilist<iactionfilter> filters, actiondescriptor actiondescriptor, idictionary<string, object> parameters)
5 {
6 actionexecutingcontext precontext = new actionexecutingcontext(controllercontext, actiondescriptor, parameters);
7
8 func<actionexecutedcontext> seed = () => new actionexecutedcontext(controllercontext, actiondescriptor, false, null)
9 {
10 result = this.invokeactionmethod(controllercontext, actiondescriptor, parameters)
11 };
12
13 func<func<actionexecutedcontext>, iactionfilter, func<actionexecutedcontext>> secondparam =
14 (func<actionexecutedcontext> next, iactionfilter filter) =>
15 {
16 func<actionexecutedcontext> returnfunc = () =>
17 {
18 return class1.invokeactionmethodfilter(filter, precontext, next);
19 };
20
21 return returnfunc;
22
23 //这个是简写
24 //return () => class1.invokeactionmethodfilter(filter, precontext, next);
25 };
26
27 return filters.reverse<iactionfilter>().aggregate(seed,
28 //(func<actionexecutedcontext> next, iactionfilter filter) => () => class1.invokeactionmethodfilter(filter, precontext, next)
29 secondparam
30 )
31 .invoke();
32 }
33
34 internal static actionexecutedcontext invokeactionmethodfilter(iactionfilter filter, actionexecutingcontext precontext, func<actionexecutedcontext> continuation)
35 {
36 filter.onactionexecuting(precontext);
37 if (precontext.result != null)
38 {
39 return new actionexecutedcontext(precontext, precontext.actiondescriptor, true, null)
40 {
41 result = precontext.result
42 };
43 }
44 bool flag = false;
45 actionexecutedcontext actionexecutedcontext = null;
46 try
47 {
48 actionexecutedcontext = continuation();
49 }
50 catch (threadabortexception)
51 {
52 actionexecutedcontext = new actionexecutedcontext(precontext, precontext.actiondescriptor, false, null);
53 filter.onactionexecuted(actionexecutedcontext);
54 throw;
55 }
56 catch (exception exception)
57 {
58 flag = true;
59 actionexecutedcontext = new actionexecutedcontext(precontext, precontext.actiondescriptor, false, exception);
60 filter.onactionexecuted(actionexecutedcontext);
61 if (!actionexecutedcontext.exceptionhandled)
62 {
63 throw;
64 }
65 }
66 if (!flag)
67 {
68 filter.onactionexecuted(actionexecutedcontext);
69 }
70 return actionexecutedcontext;
71 }
72
73 protected virtual actionresult invokeactionmethod(controllercontext controllercontext, actiondescriptor actiondescriptor, idictionary<string, object> parameters)
74 {
75 object actionreturnvalue = actiondescriptor.execute(controllercontext, parameters);
76 return this.createactionresult(controllercontext, actiondescriptor, actionreturnvalue);
77 }
78
79 protected virtual actionresult createactionresult(controllercontext controllercontext, actiondescriptor actiondescriptor, object actionreturnvalue)
80 {
81 if (actionreturnvalue == null)
82 {
83 return new emptyresult();
84 }
85 actionresult arg_29_0;
86 if ((arg_29_0 = (actionreturnvalue as actionresult)) == null)
87 {
88 arg_29_0 = new contentresult();
89 //(arg_29_0 = new contentresult()).content = convert.tostring(actionreturnvalue, cultureinfo.invariantculture);
90 (arg_29_0 as contentresult).content = convert.tostring(actionreturnvalue, cultureinfo.invariantculture);
91 }
92 return arg_29_0;
93 }
94
95 }
咋一看，还是不知所云，一步一步来，
首先，我们先要知道 aggregate 这个扩展方法是怎么执行的，直接看源码如下
看了源码就很容易理解了，它就是遍历数据源来循环执行传递过来的委托，并把结果当成参数，执行下一次循环的委托。
所有我整理了一个容易理解的一串代码
1 public class class2
2 {
3
4 public void test()
5 {
6 var precontext = new actionexecutingcontext();
7
8 func<actionexecutedcontext> seed = () =>
9 {
10 console.writeline("执行action");
11 return new actionexecutedcontext();
12 };
13
14 int[] arr = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
15
16 func<func<actionexecutedcontext>, int, func<actionexecutedcontext>> secondparam =
17 (func<actionexecutedcontext> next, int filter) =>
18 {
19 return () => this.getstr(next, filter, precontext);
20 };
21
22 var refunc2 = arr.reverse().aggregate<int, func<actionexecutedcontext>>(seed, secondparam);
23 refunc2.invoke();
24
25 }
26
27 public actionexecutedcontext getstr(func<actionexecutedcontext> func, int filter, actionexecutingcontext precontext)
28 {
29
30 console.writeline("before action----" + filter + "----" + precontext.tostring());
31
32 var res = func.invoke();
33
34 console.writeline("before action----" + filter + "----" + res.tostring());
35
36 return res;
37 }
38
39 }
我是用一个int数组来模拟iactionfilter集合，其它的写法都和mvc框架的写法一样。
运行结果为 如图
看到这里，你是否明白了，它就是通过 委托里嵌套委托 来巧妙的实现了俄罗斯套娃的形式来实现iactionfilter过滤器和action方法的执行。
如对本文有疑问，请在下面进行留言讨论，广大热心网友会与你互动！！ 点击进行留言回复
win10如何启用管理员账户 win10禁用/启用管理员账户的方法
win10怎么查看驱动是否异常 Win10检测驱动程序是否正常的方法
Windows10系统任务栏无效图标怎么删除 通过注册表一键快速删除
Win10系统自动重启怎么办 Win10系统自动重启的关闭方法
怎么减少win10笔记本功耗 详谈笔记本硬件功耗大的原因和解决办法
网友评论