Ajax使用小结

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Ajax使用小结

    项目真正使用，不可能每一条处理就刷新页面与服务器交互提交一次；也不能在后台每处理一次就刷新页面与服务器交互，所以在这里使用Ajax非常必要，以下就以简单的例子说明Ajax在此的使用过程。

添加属性

textBox.Attributes.Add("Onblur", "javascript:return CheckFraction(event.srcElement)&&JudgeQuestions('" + tableName.Trim() + "','" + id + "','" + textBox.ID + "')");

JS代码

//声明XMLHttpRequest对象
var xmlHttp;
function createXMLHTTP() {if (window.XMLHttpRequest) {xmlHttp = new XMLHttpRequest(); //其它浏览器}else if (window.ActiveXObject) {try {xmlHttp = new ActiveXObject("Msxml2.XMLHTTP"); //IE老版本}catch (e){ }try {xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); //IE新版本 }catch (e) {alert('创建XMLHTTP对象失败！');}if (!xmlHttp) {window.alert("不能创建XMLHttpRequest对象实例!");return false;}}
}function JudgeQuestions(tableName, questionId, TextBoxId) {//读取分数ctl00$ContentPlaceHolder1$t_TextBoxId = "ContentPlaceHolder1_" + TextBoxId;var fraction = document.getElementById(TextBoxId).value;var pattern = /^[0-9]+(.[0-9]{1})?|([0-9]|[1-9][0-9]|100)$/;var flag = pattern.test(fraction);if (flag == false) {alert("分数应该是数字类型");return false;}createXMLHTTP(); //创建XMLHttpRequest对象var url = "MarkToServer.aspx?tableName=" + tableName + "&id=" + questionId + "&fraction=" + fraction + "&Event=" + "Judge";xmlHttp.open("Post", url, true);xmlHttp.onreadystatechange = JudgeResult;xmlHttp.send(null);
}//判断判卷是否成功
function JudgeResult() {if (xmlHttp.readyState == 4) {if (xmlHttp.status == 200) {if (xmlHttp.responseText == "true") {}else {alert("评分失败，请重新评分或者联系管理员");}}}
}

MarkToServer.aspx

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Web.Security;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using ExamSys.Pages.Common;
using Entity;
using BLL.BLLPaperManage;public partial class Pages_UIPaperManage_MarkToServer : System.Web.UI.Page
{OnlineMarkBLL markBLL = new OnlineMarkBLL();protected void Page_Load(object sender, EventArgs e){//分别得到数据表名称、试题id、试题所得分数string tableName = Request.QueryString["tableName"].ToString();int id = Convert.ToInt32(Request.QueryString["id"].ToString());int fraction = Convert.ToInt32(Request.QueryString["fraction"].ToString());if (Request.QueryString["Event"].ToString() == "Judge"){if (markBLL.UpdateOneQuestionRecordFraction(tableName, id, fraction)){Response.Write("true");Response.End();}else{Response.Write("false");Response.End();}}}
}

BLL层

/// <summary>
/// 更新一条答题记录
/// </summary>
/// <returns></returns>
public bool UpdateOneQuestionRecordFraction(string tableName, int id, int fraction)
{onlineMarkDAL.ModifyFraction(tableName, id, fraction);return true;
}

    /// 更改评分/// </summary>/// <param name="id"></param>/// <param name="fraction"></param>/// <returns></returns>public bool ModifyFraction(string tableName, long id, int fraction){try{string cmdText = "";//定义存储过程字符串，并且赋值cmdText = "update " + tableName + " set fraction=@fraction where id=@id";//给参数赋值SqlParameter[] paras = new SqlParameter[]{new SqlParameter ("@id",id ),new SqlParameter ("@fraction",fraction )};//执行命令if (SQLHelper.ExecuteNonQuery(cmdText, paras, CommandType.Text) >= 0){return true;}return false;}catch (Exception e){throw e;}finally {SQLHelper.Close();}}
}

    原理比较简单，就是给TextBox控件添加属性，当焦点离开时触发JS的JudgeQuestions函数，JS再与MarkToServer.aspx交互（使用ashx更好），再就是常见的三层结构：UI层调用BLL层的UpdateOneQuestionRecordFraction，BLL层再调用DAL层的ModifyFraction函数即可（实体层和SQLHelper省略）。

    难的不是怎么使用，而是在什么时候想到使用。