webservice+Jquery返回Json格式 天高地厚

 <script type="text/javascript" src="Scripts/jquery-1.4.1-vsdoc.js"></script>
    <script type="text/javascript">
        $(function () {
            $("#btn").click(function () {
                $.ajax({
                    type: "POST",
                    url: "data.asmx/GetUser",
                    data: { orderType: "asc" }, //注意这个地方的orderType是调用da.asmx（webservice）中GetUser的参数
                    success: function (data) {
                        debugger
                        //将返回字符串转换为json对象
                        //如果
                        var json = null;
                        try {
                            json = eval('(' + data.text + ')');
                        } catch (e) {
                            alert("返回字符串不是json格式!");
                            return;
                        }
                        alert(json.d);
                    }
                });
            })
        })

    </script>
    <div>
        <h1>
            Jquery+WebService=》返回Json类型</h1>
        <hr />
        <input id="txt" type="text" size="20" runat="server" />
        <input id="btn" type="button" value="调用WebServer方式111" />
        <hr />
    </div>

Webservice代码（data.asmx）

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;
using System.Web.Script.Serialization;//添加它为了方便序列化

[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
//若要允许使用 ASP.NET AJAX 从脚本中调用此 Web 服务，请取消对下行的注释。 

[System.Web.Script.Services.ScriptService()]//如果不添加它，Json访问WebService会出错
public class data : System.Web.Services.WebService
{
    [WebMethod]
    public string HelloWorld()
    {
        return "Hello World";
    }

    [WebMethod]
    public string GetUser(string orderType)
    {
        User use1 = new User
        {
            ID = 1,
            Name = "GXW",
            PWD = "123456"
        };

        User use2 = new User
        {
            ID = 2,
            Name = "GXW2",
            PWD = "23456"
        };

        User use3 = new User
        {
            ID = 3,
            Name = "3GXW2",
            PWD = "3456"
        };
        List<User> list = new List<User>();
        list.Add(use1);
        list.Add(use2);
        list.Add(use3);
        return ToJSON(list);
    }

   //对数据序列化，返回JSON格式 

   public  string ToJSON(object obj)
    {
        JavaScriptSerializer serializer = new JavaScriptSerializer();
        return serializer.Serialize(obj);
    }
}

public class User 
{
    public int ID { get; set; }
    public string Name{get;set;}
    public string PWD { get; set; }
}