$.ajax

  搞了一下午,本来打算使用ajaxSubmit的,但是总是不执行,现在总结一下$.ajax.

1,(1)首先建立一个页面Default.aspx,其中的body和scirpt如下:

text类型
<form id="form1" runat="server">    
     <div id='divcode'>
     <img alt='验证码' src='' id='img' />
     <input type='text' id='code' />
     <input type='button' id='btn' value='发送' />
     </div>
</form>

<script type="text/javascript" language="javascript">

    $(function () {  

        $("#btn").click(function () {           
            var code = $("#code").val();
            var options = {
                "url": "Handler.ashx",
                "type": "post",
                "dataType": "json"
            };
            alert("提交之前");

            $.ajax({
                url: "Handler.ashx?code="+code+"",//code通过get发送
                type: "post",
                data: options,
                dataType: "text",
                success: function (a) {
                    alert("成功");
                    alert(a);
                }
            });
            alert("结束");
        });
    });

</script>

(2)同目录下建立一个Handler.ashx,代码如下:

text类型
    public void ProcessRequest (HttpContext context) 
    {
        context.Response.ContentType ="text/plain"; //响应内容是文本  

        string url = context.Request.Form["url"];//获取提交的参数   
        string code = context.Request.QueryString["code"];//url中的参数
        if (code=="1")
        {
            context.Response.Write(url);
            return;  //根据条件,特殊情况提前返回,相当于向一个方法请求
        }
        
        context.Response.Write("你好");
        context.Response.Write("世界");//两个都会输出             
    }

2,下面是网上一个例子:

ajax到一个webform.aspx页面或.asmx服务页面,指定url到某个方法。

前台
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <script src="jquery-1.4.2.min.js" type="text/javascript"></script>

    <script type="text/javascript" language="javascript">
        // //无参数调用
        $(function () {
            $('#btn1').click(function () {
                $.ajax({
                    type: "POST",   //访问WebService使用Post方式请求
                    contentType: "application/json", //这是发送给服务器的数据格式
                    url: "Default2.aspx/HelloWorld", //调用WebService的地址和方法名称组合 ---- WsURL/方法名
                    data: "{}",  //这里是要传递的参数,格式为 data: "{paraName:paraValue}",下面将会看到       
                    dataType: 'json',   //WebService 会返回Json类型

                    success: function (result) {     //回调函数,result,返回值
                        alert(result.d);   //微软返回的json形式{"d":"你好,世界"}
                        var obj1 = eval(result); //将json字符串转为json对象
                        alert(obj1.d);  //输出: 你好,世界                      
                    }
                });
            });
        });

        //有参数调用
        $(function () {
            $("#btn2").click(function () {
                $.ajax({
                    type: "POST",
                    contentType: "application/json",
                    url: "Default2.aspx/GetWish",
                    data: "{value1:'心想事成',value2:'万事如意',value3:'牛牛牛',value4:2009}",
                    dataType: 'json',
                    success: function (result) {
                        alert(result.d); //响应 {"d":"祝您在2009年里 心想事成、万事如意、牛牛牛"}
                        var obj1 = eval(result);
                        alert(obj1.d);
                    }
                });
            });
        });

        //返回集合(引用自网络,很说明问题)
        $(function () {
            $("#btn3").click(function () {
                $.ajax({
                    type: "POST",
                    contentType: "application/json",
                    url: "Default2.aspx/GetArray",
                    data: "{i:10}",
                    dataType: 'json',
                    success: function (result) {
                        var obj = eval(result.d); //d对应的是一个数组 响应{"d":[10,9,8,7,6,5,4,3,2,1,0]}
                        alert(obj[1]);
                        $(result.d).each(function () { //遍历所有元素
                            alert(this); //
                            $('#dictionary').append(this.toString() + " ");
                            alert(result.d.join(" | "));
                        });
                    }
                });
            });
        });


        //返回复合类型
        $(document).ready(function () {
            $('#btn4').click(function () {
                $.ajax({
                    type: "POST",
                    contentType: "application/json",
                    url: "Default2.aspx/GetClass",
                    data: "{}",
                    dataType: 'json',
                    success: function (result) {
                        $(result.d).each(function () { //返回 {"d":{"__type":"Default2+Class1","ID":"1","Value":"牛年大吉"}}
                            alert(this);
                            $('#dictionary').append(this['ID'] + " " + this['Value']);
                            alert(result.d.join(" | "));
                        });
                    }
                });
            });
        });


    
    
    </script>


</head>
<body>
    <form id="form1" runat="server">
    <div>
    <input type="button" id="btn1" value="HelloWorld"/> 
    <input type="button" id="btn2" value="传入参数"/> 
    <input type="button" id="btn3" value="返回集合"/> 
    <input type="button" id="btn4" value=" 返回复合类型"/> 
    </div>
    <div id="dictionary">dictionary
    </div>
    </form>
</body>
</html>
后台
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.Services; //使用微软自带ajax

public partial class Default2 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
       
    }
    [WebMethod]
    public static string  HelloWorld()
    {
        return "你好,世界";
    }
    [WebMethod]
    public static string GetWish(string value1, string value2, string value3, int value4)
    {
        return string.Format("祝您在{3}年里 {0}、{1}、{2}", value1, value2, value3, value4);
    }
    /// <summary>
    /// 返回集合
    /// </summary>
    /// <param name="i"></param>
    /// <returns></returns>
    [WebMethod]
    public static List<int> GetArray(int i)
    {
        List<int> list = new List<int>();
        while (i >= 0)
        {
            list.Add(i--);
        }
        return list;
    }
    /// <summary>
    /// 返回一个复合类型
    /// </summary>
    /// <returns></returns>
    [WebMethod]
    public static Class1 GetClass()
    {
        return new Class1 { ID = "1", Value = "牛年大吉" };
    }
    public class Class1
    {
        public string ID { get; set; }
        public string Value { get; set; }
    }
}

利用Jquery让返回的各类数据(string、集合(List<>)、类)以Json数据格式返回,为什么要用到result.d
  这里我们顺带讲下Json
  Json简单讲就是Javascript对象或数组.

 Json形式一: javascript对象    { "firstName": "Brett", "lastName":"McLaughlin", "email": "aaaa" }   

  Json形式二: javascript数组    [{ "firstName": "Brett", "lastName":"McLaughlin", "email": "aaaa" },

                                 { "firstName": "Jason", "lastName":"Hunterwang", "email": "bbbb"}]

  当然javascript 数组和对象可以互相嵌套.如形式一中的"Brett"可以换成一个Js数组或Js对象.那微软的Ajax返回的是哪种形式呢.是第一种.

  微软框架默认返回一个  { "d": "后台返回的数据" }

3,ajax到一般应用程序, .ashx文件

用这种方法一般是我们要在ashx文件里手动写好返回的Json格式的数据返回给前台用
ashx 你可以配成Json格式一或Json格式二

前台
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <script src="jquery-1.4.2.min.js" type="text/javascript"></script>

    <script type="text/javascript" language="javascript">

        $(function () {
            $("#btn1").click(function () {
                $.ajax({
                    type: "POST",
                    url: "Handler.ashx?type=1",
                    dataType: "json",
                    success: function (data) {
                        alert(data.name); //返回的为 Json格式一(Js对象)                      
                    }
                });
            });
        });


        $(function () {
            $("#btn2").click(function () {
                $.ajax({
                    type: "POST",
                    url: "Handler.ashx?type=2",
                    dataType: "json",
                    success: function (data) {
                        // 返回的为 Json格式二(Js对象)
                        alert(data[0].name);
                        $(data).each(function (i) {
                            alert(data[i].name);
                        });
                    }
                });
            });
        });

    
    </script>


</head>
<body>
    <form id="form1" runat="server">
   
    <input type="button" id="btn1" value="返回类型1"/> 
    <input type="button" id="btn2" value="返回类型2"/> 
    
    </form>
</body>
</html>
Handler.ashx
<%@ WebHandler Language="C#" Class="Handler" %>

using System;
using System.Web;
using System.Web.Script.Serialization;
public class Handler : IHttpHandler 
{
    
    public void ProcessRequest (HttpContext context) 
    {
      
        JavaScriptSerializer jss = new JavaScriptSerializer();
        context.Response.ContentType = "text/plain";
        string type = context.Request.QueryString["type"];
        if (type == "1")
        {
            // 返回的为Json格式一 Js对象
            string data = "{\"name\":\"wang\",\"age\":25}";
            context.Response.Write(data);
            return;//下面的不会执行
        }
        if (type == "2")
        {
            // 返回的为Json格式二 Js数组
            string data = "[{\"name\":\"wang\",\"age\":25},{\"name\":\"zhang\",\"age\":22}]";
            context.Response.Write(data);
        }        
    }

  
    public bool IsReusable 
    {
        get 
        {
            return false;
        }
    }

}

使用Dictionary和List来代替拼接字符串。

View Code
<%@ WebHandler Language="C#" Class="Handler" %>

using System;
using System.Web;
using System.Web.Script.Serialization;
using System.Collections.Generic;
public class Handler : IHttpHandler 
{
    
    public void ProcessRequest (HttpContext context) 
    {
      
        JavaScriptSerializer jss = new JavaScriptSerializer();
        context.Response.ContentType = "text/plain";
        string type = context.Request.QueryString["type"];
        if (type == "1")
        {
            // 返回的为Json格式一 Js对象
            //使用dic不用拼字符串
            Dictionary<string, string> dic = new Dictionary<string, string>();//
            dic.Add("name", "");
            dic.Add("age", "23");
            context.Response.Write(jss.Serialize(dic));//输出json形式         
            //string data = "{\"name\":\"wang\",\"age\":25}";
            //context.Response.Write(data);
            return;//下面的不会执行
        }
        if (type == "2")
        {
            // 返回的为Json格式二 Js数组
            List<Dictionary<string, string>> list = new List<Dictionary<string, string>>();
            Dictionary<string, string> dic1 = new Dictionary<string, string>();
            dic1.Add("name", "Wang");
            dic1.Add("age", "24");
            Dictionary<string, string> dic2 = new Dictionary<string, string>();
            dic2.Add("name", "Zhang");
            dic2.Add("age", "35");
            list.Add(dic1);
            list.Add(dic2);   
            
            //string data = "[{\"name\":\"wang\",\"age\":25},{\"name\":\"zhang\",\"age\":22}]";
            context.Response.Write(jss.Serialize(list));
        }        
    }

  
    public bool IsReusable 
    {
        get 
        {
            return false;
        }
    }

}

4

讲到这里基本概念也讲得差不多了. 这里再讲一个够常碰到的例子就是如何把DataTabel转换成Json格式从而好让前台页面调用.

View Code
/// <summary>
    /// DataTable转Json
    /// </summary>
    /// <param name="dtb"></param>
    /// <returns></returns>
    private string Dtb2Json(DataTable dtb)
    {
        JavaScriptSerializer jss = new JavaScriptSerializer();
        ArrayList dic = new ArrayList();
        foreach (DataRow row in dtb.Rows)
        {
            Dictionary<string, object> drow = new Dictionary<string, object>();
            foreach (DataColumn col in dtb.Columns)
            {
                drow.Add(col.ColumnName, row[col.ColumnName]);
            }
            dic.Add(drow);
        }
        return jss.Serialize(dic);
    }
View Code
/// <summary>
    /// Json转DataTable
    /// </summary>
    /// <param name="json"></param>
    /// <returns></returns>
    private DataTable Json2Dtb(string json)
    {
        JavaScriptSerializer jss = new JavaScriptSerializer();
        ArrayList dic = jss.Deserialize<ArrayList>(json);
        DataTable dtb = new DataTable();

        if (dic.Count > 0)
        {
            foreach (Dictionary<string, object> drow in dic)
            {
                if (dtb.Columns.Count == 0)
                {
                    foreach (string key in drow.Keys)
                    {
                        dtb.Columns.Add(key, drow[key].GetType());
                    }
                }

                DataRow row = dtb.NewRow();
                foreach (string key in drow.Keys)
                {

                    row[key] = drow[key];
                }
                dtb.Rows.Add(row);
            }
        }
        return dtb;
    }
View Code
$.ajax({
type: "POST",
url: "Handler.ashx", 
dataType: "json",
success: function(data){
  var table = $("<table border='1'></table>");
  for (var i = 0; i < data.length; i++) {
  o1 = data[i];
  var row = $("<tr></tr>");
  for (key in o1)
  {
     var td = $("<td></td>");
     td.text(o1[key].toString());
     td.appendTo(row);}
     row.appendTo(table);
   }
   table.appendTo($("#back"));
}
});

http://www.cnblogs.com/xiaowu/archive/2011/09/07/2169283.html

原文地址:https://www.cnblogs.com/wang7/p/2748340.html