04-人员增删改查

案例：个人信息管理。

l 使用NVelocity的开发方式重写登录程序，把NVelocity封装成
RenderTemplate方法。
l 这种HttpHandler+ NVelocity的方式非常类似于PHP+smarty的开
发方式，也有利于理解asp.net mvc。HttpHandler就是Controller
，模板就是View， Controller不操作View的内部细节，只是把数
据给View，由View自己控制怎样显示。
l 字段：Id、姓名、年龄、个人网址（可以为空）。
l 列表页面和编辑界面：PersonList.aspx、
PersonEdit.aspx?Action=AddNew、
PersonEdit.aspx?Action=Edit&Id=2（在PersonEdit页面判断是
否传过来了save按钮来判断是加载还是保存。渲染页面的时候把
Action和Id保存在隐藏字段中。保存成功后Redirect回List页面）
l 进一步案例：有关联字段，比如班级，实现备注

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

namespace CRUDTest1
{
    /// <summary>
    /// PersonList 的摘要说明
    /// </summary>
    public class PersonList : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "text/html";
            DataTable dt =
                SqlHelper.ExecuteDataTable("select * from T_Persons");
            //DataTable不是集合，所以无法foreach遍历，DataTable的Rows属性
            //代表表格中的数据行的集合（DataRow的集合），一般传递DataRowCollection
            //给模板方便遍历
            string html = CommonHelper.RenderHtml("PersonList.htm", dt.Rows);
            
            context.Response.Write(html);

            //MVC：
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}

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

namespace CRUDTest1
{
    /// <summary>
    /// PersonEdit 的摘要说明
    /// </summary>
    public class PersonEdit : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "text/html";
            //PersonEdit.ashx?action=AddNew
            //PersonEdit.ashx?action=Edit&Id=3
            string action = context.Request["Action"];
            if (action == "AddNew")
            {
                //判断是否含有Save并且等于true，如果是的话就说明是点击【保存】按钮请求来的
                bool save = Convert.ToBoolean(context.Request["Save"]);
                if (save)//是保存
                {
                    string name = context.Request["Name"];
                    int age = Convert.ToInt32(context.Request["Age"]);
                    string email = context.Request["Email"];
                    long classId = Convert.ToInt32(context.Request["ClassId"]);
                    SqlHelper.ExecuteNonQuery("Insert into T_Persons(Name,Age,Email,ClassId) values(@Name,@Age,@Email,@ClassId)", new SqlParameter("@Name", name)
                        , new SqlParameter("@Age", age)
                        , new SqlParameter("@Email", email)
                        , new SqlParameter("@ClassId", classId));
                    context.Response.Redirect("PersonList.ashx");//保存成功返回列表页面
                }
                else
                {
                    //string html = CommonHelper.RenderHtml("PersonEdit.htm", new { Name = "", Age = 20, Email = "@rupeng.com" });
                    //var data = new { Name = "", Age = 20, Email = "@rupeng.com" };
                    DataTable dtClasses = SqlHelper.ExecuteDataTable("select * from T_Classes");
                    var data = new { Action = "AddNew", Person = new { Name = "", Age = 20, Email = "@rupeng.com" }, Classes = dtClasses.Rows };
                    string html = CommonHelper.RenderHtml("PersonEdit.htm", data);
                    context.Response.Write(html);
                }
            }
            else if (action == "Edit")
            {
                bool save = Convert.ToBoolean(context.Request["Save"]);
                if (save)
                {
                    string name = context.Request["Name"];
                    int age = Convert.ToInt32(context.Request["Age"]);
                    string email = context.Request["Email"];
                    long id = Convert.ToInt64(context.Request["Id"]);
                    long classId = Convert.ToInt64(context.Request["ClassId"]);
                    SqlHelper.ExecuteNonQuery("update T_Persons set Name=@Name,Age=@Age,Email=@Email,ClassId=@ClassId where Id=@Id", new SqlParameter("@Name", name)
                        , new SqlParameter("@Age", age)
                        , new SqlParameter("@Email", email)
                        , new SqlParameter("@Id", id)
                        , new SqlParameter("@ClassId", classId));
                    context.Response.Redirect("PersonList.ashx");//保存成功返回列表页面
                }
                else
                {
                    long id = Convert.ToInt64(context.Request["Id"]);
                    DataTable dt = SqlHelper.ExecuteDataTable("select * from T_Persons where Id=@Id", new SqlParameter("@Id", id));
                    if (dt == null || dt.Rows == null || dt.Rows.Count <= 0)
                    {
                        context.Response.Write("没有找到Id=" + id + "的数据");
                        return;
                    }
                    else if (dt.Rows.Count > 1)
                    {
                        context.Response.Write("找到多条Id=" + id + "的数据");
                    }
                    else
                    {
                        DataRow row = dt.Rows[0];
                        DataTable dtClasses = SqlHelper.ExecuteDataTable("select * from T_Classes");
                        var data = new { Action = "Edit", Person = row, Classes = dtClasses.Rows };
                        string html = CommonHelper.RenderHtml("PersonEdit.htm", data);
                        context.Response.Write(html);
                    }
                }
            }
            else if (action == "Delete")
            {
                long id = Convert.ToInt64(context.Request["Id"]);
                SqlHelper.ExecuteNonQuery("delete from T_Persons where Id=@Id", new SqlParameter("@Id", id));
                context.Response.Redirect("PersonList.ashx");
            }
            else
            {
                context.Response.Write("Action参数错误！");
            }
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using NVelocity.App;
using NVelocity.Runtime;
using NVelocity;

namespace CRUDTest1
{
    public class CommonHelper
    {
        /// <summary>
        /// 用data数据填充templateName模板，渲染生成html返回
        /// </summary>
        /// <param name="templateName"></param>
        /// <param name="data"></param>
        /// <returns></returns>
        public static string RenderHtml(string templateName, object data)
        {
             VelocityEngine vltEngine = new VelocityEngine();
            vltEngine.SetProperty(RuntimeConstants.RESOURCE_LOADER, "file");
            vltEngine.SetProperty(RuntimeConstants.FILE_RESOURCE_LOADER_PATH, System.Web.Hosting.HostingEnvironment.MapPath("~/templates"));//模板文件所在的文件夹
            vltEngine.Init();

            VelocityContext vltContext = new VelocityContext();
            vltContext.Put("Data", data);//设置参数，在模板中可以通过$data来引用

            Template vltTemplate = vltEngine.GetTemplate(templateName);
            System.IO.StringWriter vltWriter = new System.IO.StringWriter();
            vltTemplate.Merge(vltContext, vltWriter);

            string html = vltWriter.GetStringBuilder().ToString();
            return html;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Configuration;
using System.Data.SqlClient;
using System.Data;

namespace CRUDTest1
{
    public static class  SqlHelper
    {
        public static readonly string connstr =
            ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;

        public static SqlConnection OpenConnection()
        {
            SqlConnection conn = new SqlConnection(connstr);
            conn.Open();
            return conn;
        }

        public static int ExecuteNonQuery(string cmdText,
            params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connstr))
            {
                conn.Open();
                return ExecuteNonQuery(conn, cmdText, parameters);
            }
        }

        public static object ExecuteScalar(string cmdText,
            params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connstr))
            {
                conn.Open();
                return ExecuteScalar(conn, cmdText, parameters);
            }
        }

        public static DataTable ExecuteDataTable(string cmdText,
            params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connstr))
            {
                conn.Open();
                return ExecuteDataTable(conn, cmdText, parameters);
            }
        }

        public static int ExecuteNonQuery(SqlConnection conn,string cmdText,
           params SqlParameter[] parameters)
        {
            using (SqlCommand cmd = conn.CreateCommand())
            {
                cmd.CommandText = cmdText;
                cmd.Parameters.AddRange(parameters);
                return cmd.ExecuteNonQuery();
            }
        }

        public static object ExecuteScalar(SqlConnection conn, string cmdText,
            params SqlParameter[] parameters)
        {
            using (SqlCommand cmd = conn.CreateCommand())
            {
                cmd.CommandText = cmdText;
                cmd.Parameters.AddRange(parameters);
                return cmd.ExecuteScalar();
            }
        }

        public static DataTable ExecuteDataTable(SqlConnection conn, string cmdText,
            params SqlParameter[] parameters)
        {
            using (SqlCommand cmd = conn.CreateCommand())
            {
                cmd.CommandText = cmdText;
                cmd.Parameters.AddRange(parameters);
                using (SqlDataAdapter adapter = new SqlDataAdapter(cmd))
                {
                    DataTable dt = new DataTable();
                    adapter.Fill(dt);
                    return dt;
                }
            }
        }

        public static object ToDBValue(this object value)
        {
            return value == null ? DBNull.Value : value;
        }

        public static object FromDBValue(this object dbValue)
        {
            return dbValue == DBNull.Value ? null : dbValue;
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>

<!--
  有关如何配置 ASP.NET 应用程序的详细消息，请访问
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->

<configuration>
    <system.web>
        <compilation debug="true" targetFramework="4.0" />
    </system.web>
  <connectionStrings>
    <add name="connstr" connectionString="Data Source=.;Initial Catalog=CRUDTest;User Id=sa;Password=123456;"></add>
  </connectionStrings>
</configuration>

<!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>
    <title>人员列表</title>
</head>
<body>
<a href="PersonEdit.ashx?Action=AddNew">新增人员</a>
<table>
    <thead>
        <tr><td>编辑</td><td>删除</td><td>姓名</td><td>年龄</td><td>邮箱</td></tr>
    </thead>
    <tbody>
        #foreach($person in $Data)
        <tr><td><a href="PersonEdit.ashx?Action=Edit&Id=$person.Id">编辑</a></td><td><a href="PersonEdit.ashx?Action=Delete&Id=$person.Id">删除</a></td><td>$person.Name</td><td>$person.Age</td><td>$person.Email</td></tr>
        #end
    </tbody>
</table>
</body>
</html>

<!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>
    <title>
        #if($Data.Action="AddNew")
        新增用户
        #else
        编辑用户$Data.Person.Name
        #end
    </title>
</head>
<body>
<form action="PersonEdit.ashx" method="post">
    <input type="hidden" name="Action" value="$Data.Action" />
    <input type="hidden" name="Save" value="true" />
    <input type="hidden" name="Id" value="$Data.Person.Id" />  
    <table>
        <tr><td>姓名：</td><td><input type="text" name="Name" value="$Data.Person.Name" /></td></tr>
        <tr><td>年龄：</td><td><input type="text" name="Age" value="$Data.Person.Age" /></td></tr>
        <tr><td>邮箱：</td><td><input type="text" name="Email" value="$Data.Person.Email" /></td></tr>
        <tr><td>班级：</td><td>
                            <select name="ClassId">
                                #foreach($class in $Data.Classes)
                                    #if($class.Id==$Data.Person.ClassId)
                                    <option value="$class.Id" selected>$class.Name</option>
                                    #else
                                    <option value="$class.Id">$class.Name</option>
                                    #end
                                #end
                            </select>
            </td></tr>
        <tr><td></td><td><input type="submit" value="保存"/></td></tr>
    </table>
</form>
</body>
</html>

案例：留言板

l 能够发表留言：标题、内容（多行普通文本）、昵称、是否匿名
l 展示留言列表（标题、内容、昵称、IP地址、日期）
l 发表留言界面和留言列表界面的头体是统一的。
l （*）深入：增加留言的分页。SQLServer2005后增加了
Row_Number函数简化实现。
l 限制结果集。返回第3行到第5行的数据（ ROW_NUMBER 不能用在
where子句中，所以将带行号的执行结果作为子查询，就可以将结果当
成表一样用了）：
• select * from
• (select *,row_number() over (order by Id asc) as num from student) as s
• where s.num between 3 and 5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using NVelocity.App;
using NVelocity.Runtime;
using NVelocity;

namespace WebApplication1
{
    public static class CommonHelper
    {
        public static string ReaderHtml(string templateName, object data)
        {
            VelocityEngine vltEngine = new VelocityEngine();
            vltEngine.SetProperty(RuntimeConstants.RESOURCE_LOADER, "file");
            vltEngine.SetProperty(RuntimeConstants.FILE_RESOURCE_LOADER_PATH, System.Web.Hosting.HostingEnvironment.MapPath("~/templates"));//模板文件所在的文件夹
            vltEngine.Init();

            VelocityContext vltContext = new VelocityContext();
            vltContext.Put("Data", data);//设置参数，在模板中可以通过$data来引用

            Template vltTemplate = vltEngine.GetTemplate(templateName);
            System.IO.StringWriter vltWriter = new System.IO.StringWriter();
            vltTemplate.Merge(vltContext, vltWriter);

            string html = vltWriter.GetStringBuilder().ToString();
            return html;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Configuration;
using System.Data.SqlClient;
using System.Data;

namespace WebApplication1
{
    public static class SqlHelper
    {
        public static readonly string connstr = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;

        public static SqlConnection OpenConnection()
        {
            SqlConnection conn = new SqlConnection(connstr);
            conn.Open();
            return conn;
        }

        public static int ExecuteNonQuery(string sql, params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connstr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(parameters);
                    return cmd.ExecuteNonQuery();
                }
            }
        }

        public static object ExecuteScalar(string sql, params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connstr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(parameters);
                    return cmd.ExecuteScalar();
                }
            }
        }

        public static DataTable ExecuteDataTable(string sql, params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connstr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.Parameters.AddRange(parameters);
                    DataSet dataset = new DataSet();
                    SqlDataAdapter adapter = new SqlDataAdapter(cmd);
                    adapter.Fill(dataset);
                    return dataset.Tables[0];
                }
            }
        }

        public static object ToDBValue(this object value)
        {
            return value == null ? DBNull.Value : value;
        }

        public static object FromDBValue(this object dbValue)
        {
            return dbValue == DBNull.Value ? null : dbValue;
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>

<!--
  有关如何配置 ASP.NET 应用程序的详细消息，请访问
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->

<configuration>
    <system.web>
        <compilation debug="true" targetFramework="4.0" />
    </system.web>
  <connectionStrings>
    <add name="connstr" connectionString="Data Source=.;Initial Catalog=LiuYanBanDB;User Id=sa;Password=123456;"/>
  </connectionStrings>
</configuration>

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

namespace WebApplication1
{
    /// <summary>
    /// ViewMsg 的摘要说明
    /// </summary>
    public class ViewMsg : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "text/html";
            DataTable dt = SqlHelper.ExecuteDataTable("select * from T_Msgs");
            var data = new { Title = "查看所有留言", Msgs = dt.Rows };
            string html = CommonHelper.ReaderHtml("ViewMsg.htm", data);
            context.Response.Write(html);
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}

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

namespace WebApplication1
{
    /// <summary>
    /// PostMsg 的摘要说明
    /// </summary>
    public class PostMsg : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "text/html";
            string save = context.Request["Save"];
            if (string.IsNullOrEmpty(save))
            {
                var data = new { Title = "超级留言板" };
                string html = CommonHelper.ReaderHtml("PostMsg.htm", data);
                context.Response.Write(html);
            }
            else
            {
                string title = context.Request["Title"];
                string msg = context.Request["Msg"];
                string nickName = context.Request["NickName"];
                bool isAnonymous = context.Request["IsAnonymous"]=="on";
                string ipAddress = context.Request.UserHostAddress;

                SqlHelper.ExecuteNonQuery("insert into T_Msgs(Title,Msg,NickName,IsAnonymous,IPAddress,PostDate) values(@Title,@Msg,@NickName,@IsAnonymous,@IPAddress,GetDate())",
                    new SqlParameter("@Title", title),
                    new SqlParameter("@Msg", msg),
                    new SqlParameter("@NickName", nickName),
                    new SqlParameter("@IsAnonymous", isAnonymous),
                    new SqlParameter("@IPAddress", ipAddress));
                context.Response.Redirect("ViewMsg.ashx");
            }
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}

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

namespace WebApplication1
{
    /// <summary>
    /// DelMsg 的摘要说明
    /// </summary>
    public class DelMsg : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "text/html";
            long id=Convert.ToInt64(context.Request["Id"]);
            SqlHelper.ExecuteNonQuery("delete from T_Msgs where Id=@Id", new SqlParameter("@Id", id));
            context.Response.Redirect("ViewMsg.ashx");
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}

<p style="text-align:center">关于我们|联系我们|版权声明|招贤纳士|公司地址</p>
</body>
</html>

<!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>
    <title>$Data.Title</title>
</head>
<body>
    <p>
        <h1>
            超级留言板</h1>
    </p>

#parse("Head.htm")
<form action="PostMsg.ashx" method="post">
<table>
    <tr>
        <td>
            昵称：<input type="text" name="NickName" /><input type="checkbox" name="IsAnonymous"
                id="IsAnonymous" /><label for="IsAnonymous">匿名</label>
        </td>
    </tr>
    <tr>
        <td>
            标题：<input type="text" name="Title" />
        </td>
    </tr>
    <tr>
        <td>
            正文：<textarea name="Msg" cols="50" rows="5"></textarea>
        </td>
    </tr>
    <tr>
        <td>
            <input type="submit" name="Save" value="发表" />
        </td>
    </tr>
</table>
</form>
#parse("Foot.htm") 

#parse("Head.htm")
<a href="PostMsg.ashx">发表留言</a>
<ol>
#foreach($Msg in $Data.Msgs)
<li>
<table>
<tr><td>昵称：</td><td>$Msg.NickName</td></tr>
<tr><td>发表日期：</td><td>$Msg.PostDate</td></tr>
<tr><td>IP地址：</td><td>$Msg.IPAddress</td></tr>
<tr><td colspan="2">$Msg.Title</td></tr>
<tr><td colspan="2">$Msg.Msg</td></tr>
<tr><td><a href="DelMsg.ashx?Id=$Msg.Id">删除</a></td></tr>
</table>
</li>
#end
</ol>
#parse("Foot.htm")