Asp.net根据形参自动获取提交数据
在Asp.Net MVC中定义Action时，要获取页面提交的参数，我们可以在方法内直接通过Request.QuestString或者Request.Form接收，也可以定义在形参中，尤为方便的是，我们甚至可以在形参中定义自定义类型（Model），不需要再 自己去new一个对象，然后判断是否存在数据，再一个一个的对属性进行赋值,极大的简化了广大码民的开发工作！
此功能其实看似很神奇，其实实现原理是很简单的。大叔在这里就给大家讲一下，如何实现这样的功能!
做这样类似的功能，我们必须用到一个.net下很强大的功能——反射，以前很多同学一听到反射，就会嚷嚷：不行不行，反射效率太低了！其实大叔说呢，这些同学一般都是要么开发才进门不久，要么呢就是本身技术功底就不杂实，就像我们老大一样，硬性规定一个可请求的地址一定要对应一个aspx页面及一个aspx.cs代码文件,他无法理解在Mvc中有些页面根本没有对应的Aspx页面的情况一样！
反射确实会造成一定的性能损耗，但是并没有我们想象中的那么恐怖，事实上我们大多数的性能瓶颈都来源于外部IO，比如数据库！而反射带来的性能损耗，很多情况下都是可以忽略不计的， 而且我们也在不知不觉中在用着反射，比如现在的各种ORM不说，Asp.Net MVC框架本身都在大量的运用反射，就算是很老的WebForm，我们的Eval也是通过反射处理的！
好，废话到此为止，下面直接进处正文！
原理如下:
1.判断请求类型，以判断数据来源，只需要考虑GET与POST即可！
2.通过反射获取方法的形参，根据参数名去Request.QueryString或者Request.Form提取值！
详细代码：
:::: {#highlighter_795673 .syntaxhighlighter .csharp} ::: toolbar ?{.toolbar_item .command_help .help} :::
+--------------------------------------+---------------------------------------------------------------------------------+
| ::: {.line .number1 .index0 .alt2} | :::::::::::::::::::::::::::::::::::::::: container |
| 1 | ::: {.line .number1 .index0 .alt2} |
| ::: | {.csharp .spaces}MethodInfo m = GetMethod(action, type);{.csharp |
| | .plain}//获取方法信息{.csharp .comments} |
| ::: {.line .number2 .index1 .alt1} | ::: |
| 2 | |
| ::: | ::: {.line .number2 .index1 .alt1} |
| | {.csharp .spaces}ParameterInfo[] info = m.GetParameters();{.csharp |
| ::: {.line .number3 .index2 .alt2} | .plain}//获取参数列表{.csharp .comments} |
| 3 | ::: |
| ::: | |
| | ::: {.line .number3 .index2 .alt2} |
| ::: {.line .number4 .index3 .alt1} | {.csharp .spaces}NameValueCollection collection;{.csharp .plain} |
| 4 | ::: |
| ::: | |
| | ::: {.line .number4 .index3 .alt1} |
| ::: {.line .number5 .index4 .alt2} | {.csharp .spaces}if{.csharp |
| 5 | .keyword} (Request.HttpMethod.ToUpper() == {.csharp .plain}"POST"{.csharp |
| ::: | .string}){.csharp .plain} |
| | ::: |
| ::: {.line .number6 .index5 .alt1} | |
| 6 | ::: {.line .number5 .index4 .alt2} |
| ::: | {.csharp .spaces}{{.csharp .plain} |
| | ::: |
| ::: {.line .number7 .index6 .alt2} | |
| 7 | ::: {.line .number6 .index5 .alt1} |
| ::: | {.csharp .spaces}collection = Request.Form;{.csharp |
| | .plain}//如果是POST请求，则从Request.Form取值{.csharp .comments} |
| ::: {.line .number8 .index7 .alt1} | ::: |
| 8 | |
| ::: | ::: {.line .number7 .index6 .alt2} |
| | {.csharp .spaces}}{.csharp .plain} |
| ::: {.line .number9 .index8 .alt2} | ::: |
| 9 | |
| ::: | ::: {.line .number8 .index7 .alt1} |
| | {.csharp .spaces}else{.csharp .keyword} |
| ::: {.line .number10 .index9 .alt1} | ::: |
| 10 | |
| ::: | ::: {.line .number9 .index8 .alt2} |
| | {.csharp .spaces}{{.csharp .plain} |
| ::: {.line .number11 .index10 .alt2} | ::: |
| 11 | |
| ::: | ::: {.line .number10 .index9 .alt1} |
| | {.csharp .spaces}collection = Request.QueryString;{.csharp |
| ::: {.line .number12 .index11 .alt1} | .plain}//GET请求的话，从Request.QueryString取值{.csharp .comments} |
| 12 | ::: |
| ::: | |
| | ::: {.line .number11 .index10 .alt2} |
| ::: {.line .number13 .index12 .alt2} | {.csharp .spaces}}{.csharp .plain} |
| 13 | ::: |
| ::: | |
| | ::: {.line .number12 .index11 .alt1} |
| ::: {.line .number14 .index13 .alt1} | |
| 14 | ::: |
| ::: | |
| | ::: {.line .number13 .index12 .alt2} |
| ::: {.line .number15 .index14 .alt2} | |
| 15 | ::: |
| ::: | |
| | ::: {.line .number14 .index13 .alt1} |
| ::: {.line .number16 .index15 .alt1} | {.csharp .spaces}object{.csharp |
| 16 | .keyword}[] value = newobject[info.Length];{.csharp .plain}//实参{.csharp |
| ::: | .comments} |
| | ::: |
| ::: {.line .number17 .index16 .alt2} | |
| 17 | ::: {.line .number15 .index14 .alt2} |
| ::: | {.csharp .spaces}for{.csharp .keyword} ({.csharp |
| | .plain}int{.csharp .keyword} i = 0; i < info.Length; i++){.csharp .plain} |
| ::: {.line .number18 .index17 .alt1} | ::: |
| 18 | |
| ::: | ::: {.line .number16 .index15 .alt1} |
| | {.csharp .spaces}{{.csharp .plain} |
| ::: {.line .number19 .index18 .alt2} | ::: |
| 19 | |
| ::: | ::: {.line .number17 .index16 .alt2} |
| | |
| ::: {.line .number20 .index19 .alt1} | ::: |
| 20 | |
| ::: | ::: {.line .number18 .index17 .alt1} |
| | {.csharp .spaces}if{.csharp |
| ::: {.line .number21 .index20 .alt2} | .keyword} (IsSystemBaseType(info[i].ParameterType.FullName)) {.csharp |
| 21 | .plain}//此处判断是否系统基本类型{.csharp .comments} |
| ::: | ::: |
| | |
| ::: {.line .number22 .index21 .alt1} | ::: {.line .number19 .index18 .alt2} |
| 22 | {.csharp .spaces}{{.csharp .plain} |
| ::: | ::: |
| | |
| ::: {.line .number23 .index22 .alt2} | ::: {.line .number20 .index19 .alt1} |
| 23 | {.csharp .spaces}object{.csharp |
| ::: | .keyword} val = collection[info[i].Name];{.csharp |
| | .plain}//是基本类型，直接从集合中取值{.csharp .comments} |
| ::: {.line .number24 .index23 .alt1} | ::: |
| 24 | |
| ::: | ::: {.line .number21 .index20 .alt2} |
| | {.csharp .spaces}if{.csharp .keyword} (val != {.csharp |
| ::: {.line .number25 .index24 .alt2} | .plain}null{.csharp .keyword}){.csharp .plain}//参数不为空{.csharp |
| 25 | .comments} |
| ::: | ::: |
| | |
| ::: {.line .number26 .index25 .alt1} | ::: {.line .number22 .index21 .alt1} |
| 26 | {.csharp .spaces}{{.csharp .plain} |
| ::: | ::: |
| | |
| ::: {.line .number27 .index26 .alt2} | ::: {.line .number23 .index22 .alt2} |
| 27 | {.csharp |
| ::: | .spaces}value[i] = Convert.ChangeType(val, info[i].ParameterType);{.csharp |
| | .plain}//进行类型转换{.csharp .comments} |
| ::: {.line .number28 .index27 .alt1} | ::: |
| 28 | |
| ::: | ::: {.line .number24 .index23 .alt1} |
| | {.csharp .spaces}}{.csharp .plain} |
| ::: {.line .number29 .index28 .alt2} | ::: |
| 29 | |
| ::: | ::: {.line .number25 .index24 .alt2} |
| | {.csharp .spaces}else{.csharp .keyword} |
| ::: {.line .number30 .index29 .alt1} | ::: |
| 30 | |
| ::: | ::: {.line .number26 .index25 .alt1} |
| | {.csharp .spaces}{{.csharp .plain} |
| ::: {.line .number31 .index30 .alt2} | ::: |
| 31 | |
| ::: | ::: {.line .number27 .index26 .alt2} |
| | {.csharp |
| ::: {.line .number32 .index31 .alt1} | .spaces}value[i] = info[i].DefaultValue;{.csharp |
| 32 | .plain}//参数为空，则取默认值{.csharp .comments} |
| ::: | ::: |
| | |
| ::: {.line .number33 .index32 .alt2} | ::: {.line .number28 .index27 .alt1} |
| 33 | {.csharp .spaces}}{.csharp .plain} |
| ::: | ::: |
| | |
| ::: {.line .number34 .index33 .alt1} | ::: {.line .number29 .index28 .alt2} |
| 34 | |
| ::: | ::: |
| | |
| ::: {.line .number35 .index34 .alt2} | ::: {.line .number30 .index29 .alt1} |
| 35 | {.csharp .spaces}}{.csharp .plain} |
| ::: | ::: |
| | |
| ::: {.line .number36 .index35 .alt1} | ::: {.line .number31 .index30 .alt2} |
| 36 | {.csharp .spaces}else{.csharp .keyword} |
| ::: | ::: |
| | |
| ::: {.line .number37 .index36 .alt2} | ::: {.line .number32 .index31 .alt1} |
| 37 | {.csharp .spaces}{{.csharp .plain} |
| ::: | ::: |
| | |
| | ::: {.line .number33 .index32 .alt2} |
| | {.csharp |
| | .spaces}value[i] = PopulateEntity(info[i].ParameterType, collection);{.csharp |
| | .plain}//自定义实体处理，还可以判断是否数组类型{.csharp .comments} |
| | ::: |
| | |
| | ::: {.line .number34 .index33 .alt1} |
| | |
| | ::: |
| | |
| | ::: {.line .number35 .index34 .alt2} |
| | {.csharp .spaces}}{.csharp .plain} |
| | ::: |
| | |
| | ::: {.line .number36 .index35 .alt1} |
| | |
| | ::: |
| | |
| | ::: {.line .number37 .index36 .alt2} |
| | {.csharp .spaces}}{.csharp .plain} |
| | ::: |
| | :::::::::::::::::::::::::::::::::::::::: |
+--------------------------------------+---------------------------------------------------------------------------------+
::::
自定义的实体的赋值也差不多，先通过反射获取实体的属性，再通过属性名去提取值
:::: {#highlighter_110336 .syntaxhighlighter .csharp} ::: toolbar ?{.toolbar_item .command_help .help} :::
+--------------------------------------+--------------------------------------------------------------------------------------------------------------------------------+
| ::: {.line .number1 .index0 .alt2} | :::::::::::::::::::::::::::::: container |
| 1 | ::: {.line .number1 .index0 .alt2} |
| ::: | {.csharp .spaces}public{.csharp .keyword} object{.csharp |
| | .keyword} PopulateEntity(Type type, System.Collections.Specialized.NameValueCollection collection){.csharp .plain} |
| ::: {.line .number2 .index1 .alt1} | ::: |
| 2 | |
| ::: | ::: {.line .number2 .index1 .alt1} |
| | {.csharp .spaces}{{.csharp .plain} |
| ::: {.line .number3 .index2 .alt2} | ::: |
| 3 | |
| ::: | ::: {.line .number3 .index2 .alt2} |
| | {.csharp .spaces}object{.csharp .keyword} entity = Activator.CreateInstance(type);{.csharp |
| ::: {.line .number4 .index3 .alt1} | .plain}//根据类型创建实例{.csharp .comments} |
| 4 | ::: |
| ::: | |
| | ::: {.line .number4 .index3 .alt1} |
| ::: {.line .number5 .index4 .alt2} | {.csharp .spaces}PropertyInfo[] propertys = type.GetProperties();{.csharp .plain}//获取所有属性{.csharp |
| 5 | .comments} |
| ::: | ::: |
| | |
| ::: {.line .number6 .index5 .alt1} | ::: {.line .number5 .index4 .alt2} |
| 6 | {.csharp .spaces}foreach{.csharp .keyword} (PropertyInfo item {.csharp .plain}in{.csharp |
| ::: | .keyword} propertys){.csharp .plain}//循环赋值{.csharp .comments} |
| | ::: |
| ::: {.line .number7 .index6 .alt2} | |
| 7 | ::: {.line .number6 .index5 .alt1} |
| ::: | {.csharp .spaces}{{.csharp .plain} |
| | ::: |
| ::: {.line .number8 .index7 .alt1} | |
| 8 | ::: {.line .number7 .index6 .alt2} |
| ::: | {.csharp .spaces}if{.csharp .keyword} (IsSystemBaseType(item.PropertyType.FullName)){.csharp .plain} |
| | ::: |
| ::: {.line .number9 .index8 .alt2} | |
| 9 | ::: {.line .number8 .index7 .alt1} |
| ::: | {.csharp .spaces}{{.csharp .plain} |
| | ::: |
| ::: {.line .number10 .index9 .alt1} | |
| 10 | ::: {.line .number9 .index8 .alt2} |
| ::: | {.csharp .spaces}if{.csharp .keyword} (collection[item.Name] != {.csharp .plain}null{.csharp |
| | .keyword}){.csharp .plain} |
| ::: {.line .number11 .index10 .alt2} | ::: |
| 11 | |
| ::: | ::: {.line .number10 .index9 .alt1} |
| | {.csharp .spaces}{{.csharp .plain} |
| ::: {.line .number12 .index11 .alt1} | ::: |
| 12 | |
| ::: | ::: {.line .number11 .index10 .alt2} |
| | {.csharp .spaces}if{.csharp .keyword} (item.PropertyType.IsValueType && {.csharp |
| ::: {.line .number13 .index12 .alt2} | .plain}string{.csharp .keyword}.IsNullOrEmpty(collection[item.Name])) {.csharp .plain}//值类型，不能为Empty{.csharp |
| 13 | .comments} |
| ::: | ::: |
| | |
| ::: {.line .number14 .index13 .alt1} | ::: {.line .number12 .index11 .alt1} |
| 14 | {.csharp .spaces}{{.csharp .plain} |
| ::: | ::: |
| | |
| ::: {.line .number15 .index14 .alt2} | ::: {.line .number13 .index12 .alt2} |
| 15 | |
| ::: | ::: |
| | |
| ::: {.line .number16 .index15 .alt1} | ::: {.line .number14 .index13 .alt1} |
| 16 | {.csharp .spaces}}{.csharp .plain} |
| ::: | ::: |
| | |
| ::: {.line .number17 .index16 .alt2} | ::: {.line .number15 .index14 .alt2} |
| 17 | {.csharp .spaces}else{.csharp .keyword} |
| ::: | ::: |
| | |
| ::: {.line .number18 .index17 .alt1} | ::: {.line .number16 .index15 .alt1} |
| 18 | {.csharp .spaces}{{.csharp .plain} |
| ::: | ::: |
| | |
| ::: {.line .number19 .index18 .alt2} | ::: {.line .number17 .index16 .alt2} |
| 19 | {.csharp |
| ::: | .spaces}item.SetValue(entity, Convert.ChangeType(collection[item.Name], item.PropertyType), {.csharp .plain}null{.csharp |
| | .keyword});{.csharp .plain} |
| ::: {.line .number20 .index19 .alt1} | ::: |
| 20 | |
| ::: | ::: {.line .number18 .index17 .alt1} |
| | {.csharp .spaces}}{.csharp .plain} |
| ::: {.line .number21 .index20 .alt2} | ::: |
| 21 | |
| ::: | ::: {.line .number19 .index18 .alt2} |
| | {.csharp .spaces}}{.csharp .plain} |
| ::: {.line .number22 .index21 .alt1} | ::: |
| 22 | |
| ::: | ::: {.line .number20 .index19 .alt1} |
| | {.csharp .spaces}}{.csharp .plain} |
| ::: {.line .number23 .index22 .alt2} | ::: |
| 23 | |
| ::: | ::: {.line .number21 .index20 .alt2} |
| | {.csharp .spaces}else{.csharp .keyword} |
| ::: {.line .number24 .index23 .alt1} | ::: |
| 24 | |
| ::: | ::: {.line .number22 .index21 .alt1} |
| | {.csharp .spaces}{{.csharp .plain} |
| ::: {.line .number25 .index24 .alt2} | ::: |
| 25 | |
| ::: | ::: {.line .number23 .index22 .alt2} |
| | {.csharp |
| ::: {.line .number26 .index25 .alt1} | .spaces}item.SetValue(entity, Convert.ChangeType(PopulateEntity(item.PropertyType, collection), item.PropertyType), {.csharp |
| 26 | .plain}null{.csharp .keyword});{.csharp .plain} |
| ::: | ::: |
| | |
| ::: {.line .number27 .index26 .alt2} | ::: {.line .number24 .index23 .alt1} |
| 27 | {.csharp .spaces}}{.csharp .plain} |
| ::: | ::: |
| | |
| | ::: {.line .number25 .index24 .alt2} |
| | {.csharp .spaces}}{.csharp .plain} |
| | ::: |
| | |
| | ::: {.line .number26 .index25 .alt1} |
| | {.csharp .spaces}return{.csharp .keyword} entity;{.csharp .plain} |
| | ::: |
| | |
| | ::: {.line .number27 .index26 .alt2} |
| | {.csharp .spaces}}{.csharp .plain} |
| | ::: |
| | :::::::::::::::::::::::::::::: |
+--------------------------------------+--------------------------------------------------------------------------------------------------------------------------------+
::::
这里面没有判断数组的处理，如果需要处理数组，只要将取出来的值使用英文逗号","分隔即可(因为浏览器提交同个参数多个值时会自动以逗号分隔)！
原理并不复杂，在Asp.Net MVC中有很多类似功能，包括整个的框架，很有多结构都很巧妙和有趣，但是真正的原理却都是很简单的！
另外喜欢.net 开发的朋友，欢迎加入本人的.net技术交流QQ群: 5089240
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