前言

刚开始做AJAX应用的时候，经常要手工解析客户端传递的参数，这个过程极其无聊，而且代码中充斥着：Request["xxx"]之类的代码。

这篇文章的目的就是告诉初学者如何自动将客户端用AJAX发送的参数自动绑定为强类型的成员属性或方法参数。

自动绑定到ASPX和ASHX

框架支持
代码如下:
using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;

 namespace Happy.Web
 {
     public interface IWantAutoBindProperty
     {
     }
 }

代码如下:
using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;

 namespace Happy.Web
 {
     [AttributeUsage(AttributeTargets.Property, AllowMultiple = true)]
     public sealed class AutoBind : Attribute
     {
     }
 }

代码如下:
using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;

 using System.Web;

 using Newtonsoft.Json;

 using Happy.ExtensionMethods.Reflection;

 namespace Happy.Web
 {
     public class JsonBinderModule : IHttpModule
     {
         public void Init(HttpApplication context)
         {
             context.PreRequestHandlerExecute += OnPreRequestHandlerExecute;
         }

         private void OnPreRequestHandlerExecute(object sender, EventArgs e)
         {
             if (!(HttpContext.Current.CurrentHandler is IWantAutoBindProperty))
             {
                 return;
             }

             var properties = HttpContext.Current.CurrentHandler.GetType().GetProperties();

             foreach (var property in properties)
             {
                 if (!property.IsDefined(typeof(AutoBind), true))
                 {
                     continue;
                 }

                 string json = HttpContext.Current.Request[property.Name];

                 var value = JsonConvert.DeserializeObject(json, property.PropertyType);

                 property.SetValue(HttpContext.Current.Handler, value);
             }
         }

         public void Dispose()
         {
         }
     }
 }

代码示例
代码如下:
<?xml version="1.0" encoding="utf-8"?>

 <configuration>

     <system.web>
       <compilation debug="false" targetFramework="4.0" />
       <httpModules>
         <add name="JsonBinderModule" type="Happy.Web.JsonBinderModule"/>
       </httpModules>
     </system.web>

 </configuration>

代码如下:
/// <reference path="../ext-all-debug-w-comments.js" />
 var data = {
     Name: '段光伟',
     Age: 28
 };

 Ext.Ajax.request({
     url: '../handlers/JsonBinderTest.ashx',
     method: 'POST',
     params: { user: Ext.encode(data) }
 });

代码如下:
<%@ WebHandler Language="C#" Class="JsonBinderTest" %>

 using System;
 using System.Web;

 using Happy.Web;

 public class JsonBinderTest : IHttpHandler, IWantAutoBindProperty
 {
     [AutoBind]
     public User user { get; set; }

     public void ProcessRequest(HttpContext context)
     {
         context.Response.ContentType = "text/plain";
         context.Response.Write(string.Format("姓名：{0}，年龄：{1}", user.Name, user.Age));
     }

     public bool IsReusable
     {
         get
         {
             return false;
         }
     }
 }

 public class User
 {
     public string Name { get; set; }

     public int Age { get; set; }
 }

运行结果

自动绑定到MVC
框架支持
代码如下:
using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;

 using System.Web.Mvc;

 using Newtonsoft.Json;

 namespace Tenoner.Web.Mvc
 {
     public class JsonBinder : IModelBinder
     {
         public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
         {
             string json = controllerContext.HttpContext.Request[bindingContext.ModelName];

             return JsonConvert.DeserializeObject(json, bindingContext.ModelType);
         }
     }
 }