本章开始将会为大家讲解NVelocity的用法，并带领大家实现一个简单的代码生成器。

　　NVelocity是一个基于.NET的模板引擎（template engine）。它允许任何人仅仅简单的使用模板语言（template language）来引用由.NET代码定义的对象。从而使得界面设计人员与.NET程序开发人员基本分离。

阅读目录

• NVelocity的常用功能简介
• 基本语法
• 实例介绍
• 工具源代码下载
• 学习使用

<table id="appMenu" style="background-color: rgb(114, 136, 172); border: solid 1px #00377a;    height: 23px; color: White; font-size: 12px; font-family: 宋体; width: 100%; cursor: default;"    cellspacing="0" cellpadding="0">    <tr>        <td style="padding-left: 5px" nowrap="">            <b>学生信息列表</b>        </td>        <td style="padding-right: 5px; text-align: right;" nowrap="">            <span><span onclick="alert(1)">新增</span> <span class="mnuBtn" onclick="alert(2)">删除</span>            </span>        </td>    </tr></table><table border="1" style="width: 100%; border: solid 1px #dbdac9; border-collapse: collapse;    table-layout: fixed; cursor: default; font-size: 12px; font-family: 宋体;" cellspacing="0"    cellpadding="0">    <colgroup>        <col width="40">        <col width="12%">        <col width="12%">        <col width="12%">        <col width="12%">        <col width="12%">        <col width="12%">        <col width="12%">        <col />    </colgroup>    <tr height="22" style="background-color: rgb(233, 231, 215);">        <th align="center">            序号        </th>        <th>            学生姓名        </th>        <th>            年级        </th>        <th>            专业        </th>        <th>            性别        </th>        <th>            考试成绩        </th>        <th>            级别        </th>        <th>            申请时间        </th>        <th>            申请状态        </th>    </tr>    #foreach( $s in $ListStudent )    <tr height="22">        <td>            $s.Num        </td>        <td>            $s.Name        </td>        <td>            $s.Grade        </td>        <td>            $s.Major        </td>        <td>                  $s.Sex        </td>        <td align="right">            #if($s.Status=="已审核") $s.Score #else            <input style="border:solid 1px black;width:95%;" value="$s.Score" />            #end        </td>        <td align="right">            #if($s.Status=="已审核") $s.Level #else            <input style="border:solid 1px black;width:95%;" value="$s.Level" />            #end        </td>        <td align="center">          $s.GetAppoveDate($s.Status)        </td>        <td align="center">            $s.Status        </td>    </tr>    #end</table>

protected void Page_Load(object sender, EventArgs e)        {            if (!IsPostBack)            {                Hashtable ht = new Hashtable();                List<Student> list = new List<Student>();                for (int i = 1; i < 10; i++)                {                    Student s = new Student();                    s.Num = i;                    s.Name = "Test"+i.ToString();                    s.Score = i.ToString();                    s.Status = i % 2 == 0 ? "未审核" : "已审核";                    s.Sex = i % 2 == 0 ? "男" : "女";                    s.Level = i.ToString ();                    s.Major = "测试";                    s.Grade = "大一";                    list.Add(s);                }                ht["ListStudent"] = list;                divTemplate.InnerHtml = FileGen.GetFileText(Server.MapPath(@"模版文件\列表模版.vm"), ht).ToString();            }        }

using System;using System.Collections.Generic;using System.Linq;using System.Text;using NVelocity.App;using Commons.Collections;using NVelocity.Runtime;using NVelocity;using NVelocity.Context;using System.IO;using System.Collections;namespace NVelocityDemo{    /// <summary>    /// SQL文件生成    /// </summary>    public class FileGen    {        /// <summary>        /// 通过模版文件路径读取文件内容        /// </summary>        /// <param name="path">模版文件路径</param>        /// <param name="ht">模版文件的参数</param>        /// <returns>StringWriter对象</returns>        public static StringWriter GetFileText(string path, Hashtable ht)        {            if (String.IsNullOrEmpty(path))            {                throw new ArgumentNullException("模版文件路径为空！");            }            try            {                string tmpPath = path.Substring(0,path.LastIndexOf(@"\"));                string filePath = path.Substring(path.LastIndexOf(@"\")+1);                //创建NVelocity引擎的实例对象                VelocityEngine velocity = new VelocityEngine();                ExtendedProperties props = new ExtendedProperties();                props.AddProperty(RuntimeConstants.RESOURCE_LOADER, "file");                props.AddProperty(RuntimeConstants.FILE_RESOURCE_LOADER_PATH, tmpPath);                props.AddProperty(RuntimeConstants.FILE_RESOURCE_LOADER_CACHE, true);                props.AddProperty(RuntimeConstants.INPUT_ENCODING, "utf-8");                props.AddProperty(RuntimeConstants.OUTPUT_ENCODING, "utf-8");                velocity.Init(props);                //从文件中读取模板                Template temp = velocity.GetTemplate(filePath);                IContext context = new VelocityContext();                foreach (string key in ht.Keys)                {                    context.Put(key, ht[key]);                }                //合并模板                StringWriter writer = new StringWriter();                temp.Merge(context, writer);                return writer;            }            catch (Exception ex)            {                throw ex;            }        }        /// <summary>        /// 通过模版文件路径读取文件内容        /// </summary>        /// <param name="path">模版文件路径</param>        /// <param name="ht">模版文件的参数</param>        /// <param name="strOutputPath">生成文件的输出路径，如c:\1.txt</param>        /// <returns>TextWriter对象</returns>        public static void GetFile(string path, Hashtable ht,string strOutputPath)        {            if (String.IsNullOrEmpty(strOutputPath))            {                throw new ArgumentNullException("模版文件输出路径为空！");            }            try            {                StringWriter stringW=GetFileText(path, ht);                StreamWriter sw = new StreamWriter(strOutputPath,false,Encoding.UTF8);                sw.Write(stringW.ToString());                sw.Close();            }            catch (Exception ex)            {                throw ex;            }        }    }}