ajax验证表单元素规范正确与否 ajax展示加载数据库数据 ajax三级联动

一、ajax验证表单元素规范正确与否

以用ajax来验证用户名是否被占用为例

1创建表单元素<input type="text" id="t">

2在js中用keyup事件来进行操作

3创建ajax格式和内容：格式：

$.ajax({

url:"哪一个服务端处理器",

data:{"自己起名",所需要传给处理器的数据},

type:"post",

dataType:"json",

success:function(aa){

//对处理器返回的值aa进行处理操作

},

error:function(){

alert("处理器连接失败");

}

});

4.代码示范

（1）建立linq

#pragma warning disable 1591
//------------------------------------------------------------------------------
// <auto-generated>
//     此代码由工具生成。
//     运行时版本:4.0.30319.17929
//
//     对此文件的更改可能会导致不正确的行为，并且如果
//     重新生成代码，这些更改将会丢失。
// </auto-generated>
//------------------------------------------------------------------------------

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.Linq;
using System.Data.Linq.Mapping;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;

[global::System.Data.Linq.Mapping.DatabaseAttribute(Name="mydb")]
public partial class chinaDataContext : System.Data.Linq.DataContext
{

    private static System.Data.Linq.Mapping.MappingSource mappingSource = new AttributeMappingSource();

  #region 可扩展性方法定义
  partial void OnCreated();
  partial void InsertChinaStates(ChinaStates instance);
  partial void UpdateChinaStates(ChinaStates instance);
  partial void DeleteChinaStates(ChinaStates instance);
  #endregion

    public chinaDataContext() :
            base(global::System.Configuration.ConfigurationManager.ConnectionStrings["mydbConnectionString"].ConnectionString, mappingSource)
    {
        OnCreated();
    }

    public chinaDataContext(string connection) :
            base(connection, mappingSource)
    {
        OnCreated();
    }

    public chinaDataContext(System.Data.IDbConnection connection) :
            base(connection, mappingSource)
    {
        OnCreated();
    }

    public chinaDataContext(string connection, System.Data.Linq.Mapping.MappingSource mappingSource) :
            base(connection, mappingSource)
    {
        OnCreated();
    }

    public chinaDataContext(System.Data.IDbConnection connection, System.Data.Linq.Mapping.MappingSource mappingSource) :
            base(connection, mappingSource)
    {
        OnCreated();
    }

    public System.Data.Linq.Table<ChinaStates> ChinaStates
    {
        get
        {
            return this.GetTable<ChinaStates>();
        }
    }
}

[global::System.Data.Linq.Mapping.TableAttribute(Name="dbo.ChinaStates")]
public partial class ChinaStates : INotifyPropertyChanging, INotifyPropertyChanged
{

    private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty);

    private string _AreaCode;

    private string _AreaName;

    private string _ParentAreaCode;

    private bool _Root;

    private short _Zone;

    private string _NavigateURL;

    #region 可扩展性方法定义
    partial void OnLoaded();
    partial void OnValidate(System.Data.Linq.ChangeAction action);
    partial void OnCreated();
    partial void OnAreaCodeChanging(string value);
    partial void OnAreaCodeChanged();
    partial void OnAreaNameChanging(string value);
    partial void OnAreaNameChanged();
    partial void OnParentAreaCodeChanging(string value);
    partial void OnParentAreaCodeChanged();
    partial void OnRootChanging(bool value);
    partial void OnRootChanged();
    partial void OnZoneChanging(short value);
    partial void OnZoneChanged();
    partial void OnNavigateURLChanging(string value);
    partial void OnNavigateURLChanged();
    #endregion

    public ChinaStates()
    {
        OnCreated();
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_AreaCode", DbType="VarChar(20) NOT NULL", CanBeNull=false, IsPrimaryKey=true)]
    public string AreaCode
    {
        get
        {
            return this._AreaCode;
        }
        set
        {
            if ((this._AreaCode != value))
            {
                this.OnAreaCodeChanging(value);
                this.SendPropertyChanging();
                this._AreaCode = value;
                this.SendPropertyChanged("AreaCode");
                this.OnAreaCodeChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_AreaName", DbType="NVarChar(20) NOT NULL", CanBeNull=false)]
    public string AreaName
    {
        get
        {
            return this._AreaName;
        }
        set
        {
            if ((this._AreaName != value))
            {
                this.OnAreaNameChanging(value);
                this.SendPropertyChanging();
                this._AreaName = value;
                this.SendPropertyChanged("AreaName");
                this.OnAreaNameChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_ParentAreaCode", DbType="VarChar(20) NOT NULL", CanBeNull=false)]
    public string ParentAreaCode
    {
        get
        {
            return this._ParentAreaCode;
        }
        set
        {
            if ((this._ParentAreaCode != value))
            {
                this.OnParentAreaCodeChanging(value);
                this.SendPropertyChanging();
                this._ParentAreaCode = value;
                this.SendPropertyChanged("ParentAreaCode");
                this.OnParentAreaCodeChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_Root", DbType="Bit NOT NULL")]
    public bool Root
    {
        get
        {
            return this._Root;
        }
        set
        {
            if ((this._Root != value))
            {
                this.OnRootChanging(value);
                this.SendPropertyChanging();
                this._Root = value;
                this.SendPropertyChanged("Root");
                this.OnRootChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_Zone", DbType="SmallInt NOT NULL")]
    public short Zone
    {
        get
        {
            return this._Zone;
        }
        set
        {
            if ((this._Zone != value))
            {
                this.OnZoneChanging(value);
                this.SendPropertyChanging();
                this._Zone = value;
                this.SendPropertyChanged("Zone");
                this.OnZoneChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_NavigateURL", DbType="VarChar(100)")]
    public string NavigateURL
    {
        get
        {
            return this._NavigateURL;
        }
        set
        {
            if ((this._NavigateURL != value))
            {
                this.OnNavigateURLChanging(value);
                this.SendPropertyChanging();
                this._NavigateURL = value;
                this.SendPropertyChanged("NavigateURL");
                this.OnNavigateURLChanged();
            }
        }
    }

    public event PropertyChangingEventHandler PropertyChanging;

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void SendPropertyChanging()
    {
        if ((this.PropertyChanging != null))
        {
            this.PropertyChanging(this, emptyChangingEventArgs);
        }
    }

    protected virtual void SendPropertyChanged(String propertyName)
    {
        if ((this.PropertyChanged != null))
        {
            this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}
#pragma warning restore 1591

（2）default页面

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
    <script src="js/jquery-1.7.1.min.js"></script><%--引用jquery--%>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <input type="text" id="t" /><span id="s"></span>
    </div>
    </form>
</body>
</html>
<script>
    $("#t").keyup(function () {//用keyup操作方式来验证
        var a = $(this).val();//先取值
        //1、将数据提交到服务端去
        $.ajax({
            url: "ajax/SelectUserName.ashx",//服务端处理器路径
            data: { "shuju": a },//将数据a提交到服务端去，”shuju“是自己随意起名
            type: "post",//规定提交方式，有post和get两种
            dataType: "json",//规定返回交互的数据类型，有”json“和”xml“。但是json比xml好用
            success: function (b) {//b为SelectUserName.ashx中返回的namejson的值
                if (b.has == "") {
                    $("#s").text("恭喜，用户名能使用").css("color","blue");
                }
                else {
                    $("#s").text("抱歉，用户名已被使用").css("color","red");
                }
            },//sucess
            error: function () {//success不成功，会走这一步！！
                alert("服务器连接失败");
            }
        });//ajax
    });//keyup

</script>

（3）服务处理器SelectUserName.ashx页面，（建立在新建文件夹ajax的里面，与default平级）

<%@ WebHandler Language="C#" Class="SelectUserName" %>

using System;
using System.Web;
using System.Linq;

public class SelectUserName : IHttpHandler {

    public void ProcessRequest (HttpContext context) {
        string name = context.Request["shuju"];//获取Default.aspx中提交的数据
       string namejson = "{\"has\":\"0\"}";//建立json，格式为{"key":"value","key":"value",..........}
       using (xinxiDataContext cnn = new xinxiDataContext())
       {
           var ss = cnn.Users.Where(r => r.UserName == name).AsEnumerable();//查询是否有该UserName,此处没有进行数据访问  此处需要引用using System.Linq;
           if (ss.Count() > )//如果有该UesrName,ss里面是有数据的，反之，没有
           {
               namejson = "{\"has\":\"1\"}";//修改namejson内容
           }
       }
       context.Response.Write(namejson);//将namejson返回出去
       context.Response.End();//关闭输出

    }

    public bool IsReusable {
        get {
            return false;
        }
    }

}

二、ajax展示加载数据库数据

1、服务处理器的作用就是用含有json的数组把数据传出来，再在web窗体端对该数组进行处理。

含有json的数组的格式：[{"key1":"value1","key2":"value2"},{"key3":"value3"}........{"keyn":"value3"}]。

2、以数据库xinxi中Uers和Nation表为例

（1）建立linq。（xinxi.dbml）

#pragma warning disable 1591
//------------------------------------------------------------------------------
// <auto-generated>
//     此代码由工具生成。
//     运行时版本:4.0.30319.17929
//
//     对此文件的更改可能会导致不正确的行为，并且如果
//     重新生成代码，这些更改将会丢失。
// </auto-generated>
//------------------------------------------------------------------------------

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.Linq;
using System.Data.Linq.Mapping;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;

[global::System.Data.Linq.Mapping.DatabaseAttribute(Name="xinxi")]
public partial class xinxiDataContext : System.Data.Linq.DataContext
{

    private static System.Data.Linq.Mapping.MappingSource mappingSource = new AttributeMappingSource();

  #region 可扩展性方法定义
  partial void OnCreated();
  partial void InsertUsers(Users instance);
  partial void UpdateUsers(Users instance);
  partial void DeleteUsers(Users instance);
  partial void InsertNation(Nation instance);
  partial void UpdateNation(Nation instance);
  partial void DeleteNation(Nation instance);
  #endregion

    public xinxiDataContext() :
            base(global::System.Configuration.ConfigurationManager.ConnectionStrings["xinxiConnectionString"].ConnectionString, mappingSource)
    {
        OnCreated();
    }

    public xinxiDataContext(string connection) :
            base(connection, mappingSource)
    {
        OnCreated();
    }

    public xinxiDataContext(System.Data.IDbConnection connection) :
            base(connection, mappingSource)
    {
        OnCreated();
    }

    public xinxiDataContext(string connection, System.Data.Linq.Mapping.MappingSource mappingSource) :
            base(connection, mappingSource)
    {
        OnCreated();
    }

    public xinxiDataContext(System.Data.IDbConnection connection, System.Data.Linq.Mapping.MappingSource mappingSource) :
            base(connection, mappingSource)
    {
        OnCreated();
    }

    public System.Data.Linq.Table<Users> Users
    {
        get
        {
            return this.GetTable<Users>();
        }
    }

    public System.Data.Linq.Table<Nation> Nation
    {
        get
        {
            return this.GetTable<Nation>();
        }
    }
}

[global::System.Data.Linq.Mapping.TableAttribute(Name="dbo.Users")]
public partial class Users : INotifyPropertyChanging, INotifyPropertyChanged
{

    private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty);

    private string _UserName;

    private string _Password;

    private bool _Sex;

    private string _NickName;

    private System.DateTime _Birthday;

    private string _Nation;

    private string _State;

    private EntityRef<Nation> _Nation1;

    #region 可扩展性方法定义
    partial void OnLoaded();
    partial void OnValidate(System.Data.Linq.ChangeAction action);
    partial void OnCreated();
    partial void OnUserNameChanging(string value);
    partial void OnUserNameChanged();
    partial void OnPasswordChanging(string value);
    partial void OnPasswordChanged();
    partial void OnSexChanging(bool value);
    partial void OnSexChanged();
    partial void OnNickNameChanging(string value);
    partial void OnNickNameChanged();
    partial void OnBirthdayChanging(System.DateTime value);
    partial void OnBirthdayChanged();
    partial void OnNationChanging(string value);
    partial void OnNationChanged();
    partial void OnStateChanging(string value);
    partial void OnStateChanged();
    #endregion

    public Users()
    {
        this._Nation1 = default(EntityRef<Nation>);
        OnCreated();
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_UserName", DbType="NVarChar(20) NOT NULL", CanBeNull=false, IsPrimaryKey=true)]
    public string UserName
    {
        get
        {
            return this._UserName;
        }
        set
        {
            if ((this._UserName != value))
            {
                this.OnUserNameChanging(value);
                this.SendPropertyChanging();
                this._UserName = value;
                this.SendPropertyChanged("UserName");
                this.OnUserNameChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_Password", DbType="NVarChar(20) NOT NULL", CanBeNull=false)]
    public string Password
    {
        get
        {
            return this._Password;
        }
        set
        {
            if ((this._Password != value))
            {
                this.OnPasswordChanging(value);
                this.SendPropertyChanging();
                this._Password = value;
                this.SendPropertyChanged("Password");
                this.OnPasswordChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_Sex", DbType="Bit NOT NULL")]
    public bool Sex
    {
        get
        {
            return this._Sex;
        }
        set
        {
            if ((this._Sex != value))
            {
                this.OnSexChanging(value);
                this.SendPropertyChanging();
                this._Sex = value;
                this.SendPropertyChanged("Sex");
                this.OnSexChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_NickName", DbType="NVarChar(20) NOT NULL", CanBeNull=false)]
    public string NickName
    {
        get
        {
            return this._NickName;
        }
        set
        {
            if ((this._NickName != value))
            {
                this.OnNickNameChanging(value);
                this.SendPropertyChanging();
                this._NickName = value;
                this.SendPropertyChanged("NickName");
                this.OnNickNameChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_Birthday", DbType="DateTime NOT NULL")]
    public System.DateTime Birthday
    {
        get
        {
            return this._Birthday;
        }
        set
        {
            if ((this._Birthday != value))
            {
                this.OnBirthdayChanging(value);
                this.SendPropertyChanging();
                this._Birthday = value;
                this.SendPropertyChanged("Birthday");
                this.OnBirthdayChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_Nation", DbType="NVarChar(20) NOT NULL", CanBeNull=false)]
    public string Nation
    {
        get
        {
            return this._Nation;
        }
        set
        {
            if ((this._Nation != value))
            {
                if (this._Nation1.HasLoadedOrAssignedValue)
                {
                    throw new System.Data.Linq.ForeignKeyReferenceAlreadyHasValueException();
                }
                this.OnNationChanging(value);
                this.SendPropertyChanging();
                this._Nation = value;
                this.SendPropertyChanged("Nation");
                this.OnNationChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_State", DbType="NVarChar(20)")]
    public string State
    {
        get
        {
            return this._State;
        }
        set
        {
            if ((this._State != value))
            {
                this.OnStateChanging(value);
                this.SendPropertyChanging();
                this._State = value;
                this.SendPropertyChanged("State");
                this.OnStateChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.AssociationAttribute(Name="Nation_Users", Storage="_Nation1", ThisKey="Nation", OtherKey="NationCode", IsForeignKey=true)]
    public Nation Nation1
    {
        get
        {
            return this._Nation1.Entity;
        }
        set
        {
            Nation previousValue = this._Nation1.Entity;
            if (((previousValue != value)
                        || (this._Nation1.HasLoadedOrAssignedValue == false)))
            {
                this.SendPropertyChanging();
                if ((previousValue != null))
                {
                    this._Nation1.Entity = null;
                    previousValue.Users.Remove(this);
                }
                this._Nation1.Entity = value;
                if ((value != null))
                {
                    value.Users.Add(this);
                    this._Nation = value.NationCode;
                }
                else
                {
                    this._Nation = default(string);
                }
                this.SendPropertyChanged("Nation1");
            }
        }
    }

    public event PropertyChangingEventHandler PropertyChanging;

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void SendPropertyChanging()
    {
        if ((this.PropertyChanging != null))
        {
            this.PropertyChanging(this, emptyChangingEventArgs);
        }
    }

    protected virtual void SendPropertyChanged(String propertyName)
    {
        if ((this.PropertyChanged != null))
        {
            this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

[global::System.Data.Linq.Mapping.TableAttribute(Name="dbo.Nation")]
public partial class Nation : INotifyPropertyChanging, INotifyPropertyChanged
{

    private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty);

    private string _NationCode;

    private string _NationName;

    private EntitySet<Users> _Users;

    #region 可扩展性方法定义
    partial void OnLoaded();
    partial void OnValidate(System.Data.Linq.ChangeAction action);
    partial void OnCreated();
    partial void OnNationCodeChanging(string value);
    partial void OnNationCodeChanged();
    partial void OnNationNameChanging(string value);
    partial void OnNationNameChanged();
    #endregion

    public Nation()
    {
        this._Users = new EntitySet<Users>(new Action<Users>(this.attach_Users), new Action<Users>(this.detach_Users));
        OnCreated();
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_NationCode", DbType="NVarChar(20) NOT NULL", CanBeNull=false, IsPrimaryKey=true)]
    public string NationCode
    {
        get
        {
            return this._NationCode;
        }
        set
        {
            if ((this._NationCode != value))
            {
                this.OnNationCodeChanging(value);
                this.SendPropertyChanging();
                this._NationCode = value;
                this.SendPropertyChanged("NationCode");
                this.OnNationCodeChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_NationName", DbType="NVarChar(20) NOT NULL", CanBeNull=false)]
    public string NationName
    {
        get
        {
            return this._NationName;
        }
        set
        {
            if ((this._NationName != value))
            {
                this.OnNationNameChanging(value);
                this.SendPropertyChanging();
                this._NationName = value;
                this.SendPropertyChanged("NationName");
                this.OnNationNameChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.AssociationAttribute(Name="Nation_Users", Storage="_Users", ThisKey="NationCode", OtherKey="Nation")]
    public EntitySet<Users> Users
    {
        get
        {
            return this._Users;
        }
        set
        {
            this._Users.Assign(value);
        }
    }

    public event PropertyChangingEventHandler PropertyChanging;

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void SendPropertyChanging()
    {
        if ((this.PropertyChanging != null))
        {
            this.PropertyChanging(this, emptyChangingEventArgs);
        }
    }

    protected virtual void SendPropertyChanged(String propertyName)
    {
        if ((this.PropertyChanged != null))
        {
            this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    private void attach_Users(Users entity)
    {
        this.SendPropertyChanging();
        entity.Nation1 = this;
    }

    private void detach_Users(Users entity)
    {
        this.SendPropertyChanging();
        entity.Nation1 = null;
    }
}
#pragma warning restore 1591

（2）dafault页面布置

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default3.aspx.cs" Inherits="Default3" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
    <script src="js/jquery-1.7.1.min.js"></script>
</head>
<body>
    <form id="form1" runat="server">
    <table style="width:100%;background-color:blue;text-align:center;">
        <thead>
            <tr style="background-color:aqua">
                <td>用户名</td>
                <td>密码</td>
                <td>性别</td>
                <td>昵称</td>
                <td>生日</td>
                <td>民族</td>
                <td>国家</td>
            </tr>
        </thead>
        <tbody id="tb">
            <%--   <tr style="background-color:gray">
                <td>用户名</td>
            </tr>--%>

        </tbody>

    </table>
        <input type="button" id="btn1" value="加载" />
    </form>
</body>
</html>
<script>
    $("#btn1").click(function () {//获取全部信息
        $.ajax({
            url: "ajax/quan.ashx",
            data: {},//获取全部信息，不需要传值
            type: "post",
            dataType: "json",
            success: function (aaa) {
                $("#tb").empty();//加载前线清空内容
                for (i in aaa)//aaa为服务处理器quan.ashx所传回来的集合
                {
                    var s = "";
                    s += "<tr style=\"background-color:gray\">";
                    s += "<td>" + aaa[i].name + "</td>";
                    s += "<td>" + aaa[i].pwd + "</td>";
                    s += "<td>" + aaa[i].sex + "</td>";
                    s += "<td>" + aaa[i].nick + "</td>";
                    s += "<td>" + aaa[i].bir + "</td>";
                    s += "<td>" + aaa[i].nation + "</td>";
                    s += "<td>" + aaa[i].sta + "</td>";
                    s += "</tr>";
                    $("#tb").append(s);
                }
            },
            error: function () {
                alert("处理器连接失败！");
            }
        });
    });
</script>

（3）服务处理器quan.ashx的布置（建立在新建文件夹ajax的里面，与default平级）

<%@ WebHandler Language="C#" Class="quan" %>

using System;
using System.Web;
using System.Linq;
using System.Collections.Generic;

public class quan : IHttpHandler {
    //{"name":"","pwd":"","sex":"","nick":"","bir":"","nation":"","sta":""}
    public void ProcessRequest (HttpContext context) {
        string n = "[";
        int count = ;
        using (xinxiDataContext cnn = new xinxiDataContext())//拼接含有json的数组：[{"key1":"value1","key2":"value2"},{"key3":"value3"}........{"keyn":"value3"}]
        {
            var all = cnn.Users;//等同于 List<ChinaStates> all = cnn.Users.ToList();查询全部信息，返回泛型集合
            foreach(Users u in all)
            {
                if (count > )
                {
                    n += ",";
                }
                n +="{\"name\":\""+u.UserName+"\",\"pwd\":\""+u.Password+"\",\"sex\":\""+u.Sex+"\",\"nick\":\""+u.NickName+"\",\"bir\":\""+u.Birthday+"\",\"nation\":\""+u.Nation+"\",\"sta\":\""+u.State+"\"}";
                count++;
            }
        }
        n += "]";
        context.Response.Write(n);
        context.Response.End();
    }

    public bool IsReusable {
        get {
            return false;
        }
    }

}

三、ajax三级联动

（1）建立linq

#pragma warning disable 1591
//------------------------------------------------------------------------------
// <auto-generated>
//     此代码由工具生成。
//     运行时版本:4.0.30319.17929
//
//     对此文件的更改可能会导致不正确的行为，并且如果
//     重新生成代码，这些更改将会丢失。
// </auto-generated>
//------------------------------------------------------------------------------

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.Linq;
using System.Data.Linq.Mapping;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;

[global::System.Data.Linq.Mapping.DatabaseAttribute(Name="mydb")]
public partial class chinaDataContext : System.Data.Linq.DataContext
{

    private static System.Data.Linq.Mapping.MappingSource mappingSource = new AttributeMappingSource();

  #region 可扩展性方法定义
  partial void OnCreated();
  partial void InsertChinaStates(ChinaStates instance);
  partial void UpdateChinaStates(ChinaStates instance);
  partial void DeleteChinaStates(ChinaStates instance);
  #endregion

    public chinaDataContext() :
            base(global::System.Configuration.ConfigurationManager.ConnectionStrings["mydbConnectionString"].ConnectionString, mappingSource)
    {
        OnCreated();
    }

    public chinaDataContext(string connection) :
            base(connection, mappingSource)
    {
        OnCreated();
    }

    public chinaDataContext(System.Data.IDbConnection connection) :
            base(connection, mappingSource)
    {
        OnCreated();
    }

    public chinaDataContext(string connection, System.Data.Linq.Mapping.MappingSource mappingSource) :
            base(connection, mappingSource)
    {
        OnCreated();
    }

    public chinaDataContext(System.Data.IDbConnection connection, System.Data.Linq.Mapping.MappingSource mappingSource) :
            base(connection, mappingSource)
    {
        OnCreated();
    }

    public System.Data.Linq.Table<ChinaStates> ChinaStates
    {
        get
        {
            return this.GetTable<ChinaStates>();
        }
    }
}

[global::System.Data.Linq.Mapping.TableAttribute(Name="dbo.ChinaStates")]
public partial class ChinaStates : INotifyPropertyChanging, INotifyPropertyChanged
{

    private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty);

    private string _AreaCode;

    private string _AreaName;

    private string _ParentAreaCode;

    private bool _Root;

    private short _Zone;

    private string _NavigateURL;

    #region 可扩展性方法定义
    partial void OnLoaded();
    partial void OnValidate(System.Data.Linq.ChangeAction action);
    partial void OnCreated();
    partial void OnAreaCodeChanging(string value);
    partial void OnAreaCodeChanged();
    partial void OnAreaNameChanging(string value);
    partial void OnAreaNameChanged();
    partial void OnParentAreaCodeChanging(string value);
    partial void OnParentAreaCodeChanged();
    partial void OnRootChanging(bool value);
    partial void OnRootChanged();
    partial void OnZoneChanging(short value);
    partial void OnZoneChanged();
    partial void OnNavigateURLChanging(string value);
    partial void OnNavigateURLChanged();
    #endregion

    public ChinaStates()
    {
        OnCreated();
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_AreaCode", DbType="VarChar(20) NOT NULL", CanBeNull=false, IsPrimaryKey=true)]
    public string AreaCode
    {
        get
        {
            return this._AreaCode;
        }
        set
        {
            if ((this._AreaCode != value))
            {
                this.OnAreaCodeChanging(value);
                this.SendPropertyChanging();
                this._AreaCode = value;
                this.SendPropertyChanged("AreaCode");
                this.OnAreaCodeChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_AreaName", DbType="NVarChar(20) NOT NULL", CanBeNull=false)]
    public string AreaName
    {
        get
        {
            return this._AreaName;
        }
        set
        {
            if ((this._AreaName != value))
            {
                this.OnAreaNameChanging(value);
                this.SendPropertyChanging();
                this._AreaName = value;
                this.SendPropertyChanged("AreaName");
                this.OnAreaNameChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_ParentAreaCode", DbType="VarChar(20) NOT NULL", CanBeNull=false)]
    public string ParentAreaCode
    {
        get
        {
            return this._ParentAreaCode;
        }
        set
        {
            if ((this._ParentAreaCode != value))
            {
                this.OnParentAreaCodeChanging(value);
                this.SendPropertyChanging();
                this._ParentAreaCode = value;
                this.SendPropertyChanged("ParentAreaCode");
                this.OnParentAreaCodeChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_Root", DbType="Bit NOT NULL")]
    public bool Root
    {
        get
        {
            return this._Root;
        }
        set
        {
            if ((this._Root != value))
            {
                this.OnRootChanging(value);
                this.SendPropertyChanging();
                this._Root = value;
                this.SendPropertyChanged("Root");
                this.OnRootChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_Zone", DbType="SmallInt NOT NULL")]
    public short Zone
    {
        get
        {
            return this._Zone;
        }
        set
        {
            if ((this._Zone != value))
            {
                this.OnZoneChanging(value);
                this.SendPropertyChanging();
                this._Zone = value;
                this.SendPropertyChanged("Zone");
                this.OnZoneChanged();
            }
        }
    }

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_NavigateURL", DbType="VarChar(100)")]
    public string NavigateURL
    {
        get
        {
            return this._NavigateURL;
        }
        set
        {
            if ((this._NavigateURL != value))
            {
                this.OnNavigateURLChanging(value);
                this.SendPropertyChanging();
                this._NavigateURL = value;
                this.SendPropertyChanged("NavigateURL");
                this.OnNavigateURLChanged();
            }
        }
    }

    public event PropertyChangingEventHandler PropertyChanging;

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void SendPropertyChanging()
    {
        if ((this.PropertyChanging != null))
        {
            this.PropertyChanging(this, emptyChangingEventArgs);
        }
    }

    protected virtual void SendPropertyChanged(String propertyName)
    {
        if ((this.PropertyChanged != null))
        {
            this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}
#pragma warning restore 1591

（2）web窗体页面布置

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default4.aspx.cs" Inherits="Default4" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
    <script src="js/jquery-1.7.1.min.js"></script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:DropDownList ID="sheng_dd" runat="server"></asp:DropDownList>
        <asp:DropDownList ID="shi_dd" runat="server"></asp:DropDownList>
        <asp:DropDownList ID="qu_dd" runat="server"></asp:DropDownList>

    </div>
    </form>
</body>
</html>
<script>
    bind($("#sheng_dd"),"","");
    function bind(drop,pcode,aa) {
        $.ajax({
            url: "ajax/China.ashx",
            data: { "pcode": pcode },
            type: "post",
            dataType: "json",
            success: function (aaa) {//aaa为数据处理完毕返回来的数组
                if (aa == "") {//如果aa=1,给省加载。
                    drop.empty();
                    for (i in aaa) {
                        var a = "<option value=\"" + aaa[i].code + "\">" + aaa[i].name + "</option>";//DropDownList在页面编译成select,所以用<option value="">text</option>
                        drop.append(a);//循环往DropDownList增加数据
                    }
                    bind($("#shi_dd"), $("#sheng_dd").val(), "");
                    bind($("#qu_dd"), $("#shi_dd").val(), "");
                }

                if (aa == "")//如果aa=2,给市加载。
                {
                    drop.empty();
                    for (i in aaa) {
                        var a = "<option value=\"" + aaa[i].code + "\">" + aaa[i].name + "</option>";//DropDownList在页面编译成select,所以用<option value="">text</option>
                        drop.append(a);//循环往DropDownList增加数据
                    }
                    bind($("#qu_dd"), $("#shi_dd").val(), "");

                }
                if (aa == "")//如果aa=3,给区加载。
                {
                    drop.empty();
                    for (i in aaa) {
                        var a = "<option value=\"" + aaa[i].code + "\">" + aaa[i].name + "</option>";//DropDownList在页面编译成select,所以用<option value="">text</option>
                        drop.append(a);//循环往DropDownList增加数据
                    }

                }

            },
            error: function () {
                alert("服务器连接失败");
            }//error

        });//ajax

    };//bind()

    $("#sheng_dd").change(function () {//sheng_dd所选变化事件
        bind($("#shi_dd"), $("#sheng_dd").val(), "");//市根据省变化
    });
    $("#shi_dd").change(function () {//shi_dd所选变化事件
        bind($("#qu_dd"), $("#shi_dd").val(), "");//区根据市变化
    });

</script>

（3）服务处理器China.ashx页面，（建立在新建文件夹ajax的里面，与default平级）

<%@ WebHandler Language="C#" Class="China" %>

using System;
using System.Web;
using System.Collections.Generic;
using System.Linq;
using System.Text;

public class China : IHttpHandler {

    public void ProcessRequest (HttpContext context) {//此处的作用就是拼接含有json的数组,格式[{"key1";:"value1","key2":"value2"}.....{"keyn":"valuen"}]
        string pcode=context.Request["pcode"];//接收传过来的数据
        StringBuilder s = new StringBuilder();
        int count = ;
        s.Append("[");
        using (chinaDataContext con = new chinaDataContext())
        {
            List<ChinaStates> list = con.ChinaStates.Where(r => r.ParentAreaCode == pcode).ToList();//根据ParentAreaCode查询符合条件的地区
            foreach (ChinaStates c in list)
            {
                if (count > )
                {
                    s.Append(",");
                }
                s.Append("{\"code\":\""+c.AreaCode+"\",\"name\":\""+c.AreaName+"\"}");
                count++;
            }
        }

        s.Append("]");
        context.Response.Write(s);
        context.Response.End();

    }

    public bool IsReusable {
        get {
            return false;
        }
    }

}

完！！