.NET：自動將請求參數綁定到ASPX、ASHX和MVC（菜鳥必看）

前言

剛開始做AJAX應用的時候，經常要手工解析客戶端傳遞的參數，這個過程極其無聊，而且代碼中充斥着：Request["xxx"]之類的代碼。

這篇文章的目的就是告訴初學者如何自動將客戶端用AJAX發送的參數自動綁定為強類型的成員屬性或方法參數。

自動綁定到ASPX和ASHX

框架支持

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Happy.Web
{
    public interface IWantAutoBindProperty
    {
    }
}

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
    {
    }
}

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()
        {
        }
    }
}

代碼示例

<?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>

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

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

<%@ 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}，年齡：{1}", user.Name, user.Age));
    }

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

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

    public int Age { get; set; }
}

運行結果

自動綁定到MVC

框架支持

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);
        }
    }
}

代碼示例

此處省略代碼示例，有興趣的朋友請留言交流。

備注

有些朋友應該能想到，這種模式不止能用在AJAX場景，其它場景也可以使用。