利用反射减少if等重复代码，听听大家的意见

利用反射减少if等重复代码，听听大家的意见 [已结贴,结贴人:sunchaohuang]

sunchaohuang
流星飞狐(oO!)
等级:

发表于：2008-06-25 10:30:06 楼主

[code=C#]在项目开发中难免存在大量的判断语句，特别是在频繁使用ajax与服务器交互的项目中，if，switch等判断语句的使用量是相当大的，为了在项目开发过程减少这类代码的使用量，我使用了反射。

该页面是Ajax回发处理的公共页面Process.aspx，由此可见这样重复写代码是十分令人厌恶的：
switch (Request["action"].ToString())
{
case "city":
InitCity(iType);
break;
case "city1":
InitCity1(iType);
break;
case "city2":
InitCity2(iType);
break;
case "ChangeEnter":
ChangeEnter();
break;
case "UpdateTime":

UpdateTime();
break;
case "FeedbackList":
FeedbackList();
break;
case "MessageBoardList":
MessageBoardList();
break;
case "WantsList":
WantsList();
break;
case "iStateChange":
iStateChange();
break;
case "seliWorkType":
seliWorkType();
break;
case "Del":
Del();
break;
case "jobwill":
SaveJobWill();
break;
case "callmode":
SaveCallMode();
break;
case "goodskill":
SaveGoodSkill();
break;
case "state":
SaveState();
break;
case "wantwork":
WantWork();
break;
case "Resumes":
Resumes();
break;
}
为了减少大家在开发过程中重复写类似的代码，这里使用了反射。
下面提供一个例子，全国省份的二级联动菜单：

1.首先创建一个专门处理Ajax回发事件的类库
using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using DBUtility;

namespace Re_Demo.AjaxProcess
{
public class City
{
StringBuilder strHtml = new StringBuilder();

#region测试
public string Test()
{
return "hello world!";

}
#endregion

#region测试
public string Test_111(int a,string b)
{
return a.ToString() + b;

}
#endregion

#region测试asdasdasd
public string Test_111r3r43()
{
return "hello world!aaabbfredbdrfa";

}
#endregion

#region根据省份填充市
/// <summary>
///填充市
/// </summary>
/// <param name="iParent">省份ID </param>
/// <returns> </returns>
public string InitCity(int iParent)
{
using (SqlDataReader rdr = SqlHelp.ExecuteReader(SqlHelp.ConnectionStringLocalTransaction, CommandType.Text, "select AutoCode,sName from S_City where iParentID=" + iParent, null))
{
strHtml.Append("城市： <select id='ddlCity'>");
strHtml.Append(" <option value='0'>---请选择--- </option>");

while (rdr.Read())
{
strHtml.Append(" <option value='" + rdr["AutoCode"].ToString() + "'>" + rdr["sName"].ToString() + " </option>");
}
}
strHtml.Append(" </select>");
return strHtml.ToString();
}

#endregion

}
}

2.数据访问类：
namespace DBUtility
{
public abstract class SqlHelp
{
public static readonly string ConnectionStringLocalTransaction = ConfigurationManager.ConnectionStrings["SQLDemo"].ConnectionString;
public static SqlDataReader ExecuteReader(string connectionString, CommandType cmdType, string cmdText,
params SqlParameter[] cmmandParameters)
{
SqlCommand cmd = new SqlCommand();
SqlConnection con = new SqlConnection(connectionString);
try
{
PrepareCommand(cmd, con, null, cmdType, cmdText, cmmandParameters);
SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
cmd.Parameters.Clear();
return rdr;
}
catch
{
con.Close();
throw;
}
}

private static void PrepareCommand(SqlCommand cmd, SqlConnection con, SqlTransaction trans, CommandType cmdtype, string
cmdText, SqlParameter[] cmdparms)
{
if (con.State != ConnectionState.Open)
con.Open();
cmd.Connection = con;
cmd.CommandText = cmdText;

if (trans != null)
cmd.Transaction = trans;
cmd.CommandType = cmdtype;

if (cmdparms != null)
foreach (SqlParameter parm in cmdparms)
cmd.Parameters.Add(parm);
}
}
}

3.前台AjaxProcess.aspx页面
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="AjaxProcess.aspx.cs" Inherits="AjaxProcess" %>
.CS页面
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Reflection;
using System.Text;

public partial class AjaxProcess : System.Web.UI.Page
{
string action;
string itype;
string classname;
string iParent;
int index;
object[] obj_parameters;
ParameterInfo[] paramterinfo;

readonly string path = ConfigurationManager.AppSettings["AjaxProcess"];

protected void Page_Load(object sender, EventArgs e)
{

//获取查询参数
action = Request["action"] != null ? Request["action"] : null;
itype = Request["itype"] != null ? Request["itype"] : null;
iParent = Request["iParent"] != null ? Request["iParent"] : null;

//动态调用方法
classname = path + "." + action;
object obj = Assembly.Load(path).CreateInstance(classname);
Type mytype = obj.GetType();
MethodInfo m = mytype.GetMethod(itype);
if (m.GetParameters().Length > 0)
{
paramterinfo = m.GetParameters();
obj_parameters = new object[m.GetParameters().Length];
string[] parameters = new string[] { };
if (iParent.IndexOf(" ¦") != -1)
{
parameters = iParent.Split(' ¦');
for (int i = 0; i < paramterinfo.Length; i++)
{
Get_Type(parameters[i], paramterinfo[i]);
}
}
else
{

Get_Type(iParent, paramterinfo[0]);
}
Response.Write(m.Invoke(obj, obj_parameters));
}
else
Response.Write(m.Invoke(obj, null));

}

private void Get_Type(string par, ParameterInfo paramterinfo)
{

switch (paramterinfo.ParameterType.ToString())
{
case "System.String":
obj_parameters[index] = par;
break;
case "System.Int32":
obj_parameters[index] = int.Parse(par);
break;
}
index++;
}
}

问题点数：100 回复次数：30 修改删除举报引用回复

3.前台Demo页面. <%@ Page Language="C#" AutoEventWireup="true" CodeFile="DEMO.aspx.cs" Inherits="DEMO" %> <!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 id="Head1" runat="server"> <title>无标题页</title> <script type="text/javascript" language="javascript"> var xmlHttp; function $(a){ return document.getElementById?document.getElementById(a):null; } function CreateXmlHttp() { try { xmlHttp = new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) { try { xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); } catch (e) { try { xmlHttp = new XMLHttpRequest(); } catch (e) { xmlHttp = false; }}} } function AjaxProcess(url,id) { CreateXmlHttp(); xmlHttp.open("POST",url); xmlHttp.onreadystatechange=function() { if(xmlHttp.readyState==4) { $(id).innerHTML=xmlHttp.responseText; } } xmlHttp.send(null); } function ChangeProvince() { // + $("ddProvince").value var id=$("divCity"); var url="AjaxProcess.aspx?action=City&iParent=3232|vfdvdf" + "&itype=Test_111"; AjaxProcess(url,"divCity"); } </script> </head> <body> <form id="form1" runat="server"> 省份：<asp:DropDownList ID="ddProvince" runat="server" onchange="ChangeProvince();"></asp:DropDownList><br /><br /> <span id="divCity"></span> <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:TP_ZDConnectionString %>" SelectCommand="SELECT AutoCode, sName FROM S_Province"></asp:SqlDataSource> </form> </body> </html> 后台.cs页面： using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; using System.Data.SqlClient; using System.Collections.Generic; using System.Drawing; using System.Reflection; public partial class DEMO : System.Web.UI.Page { protected DataRow EnterDR; protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { ProCity(); } } public void ProCity() { ddProvince.DataSource = SqlDataSource1; ddProvince.DataTextField = "sName"; ddProvince.DataValueField = "AutoCode"; ddProvince.DataBind(); ListItem item = new ListItem("---请选择---", ""); ddProvince.Items.Insert(0, item); } } 上面写的不清楚，也许会纯在些遗漏，下面提供一个demo下载有需要的可以下载来看，里面还有个省份-市区数据库： http://download.csdn.net/user/sunchaohuang