使用T4模板创建一个例子

1、创建项目，添加新项，名称处填写Messages.tt，如下图：

添加后，Messages.tt文件内容如下：

 <#@ template debug="false" hostspecific="false" language="C#" #>
 <#@ output extension=".txt" #>

2、创建一个实体对象MessageEntry，用以传递模版信息，具体代码如下：

     public class MessageEntry
     {
         public string Id { get; private set; }
         public string Value { get; private set; }
         public string Category { get; private set; }
         public MessageEntry(string id, string value, string category)
         {
             this.Id = id;
             this.Value = value;
             this.Category = category;
         }

         public string Format(params object[] args)
         {
             return string.Format(this.Value, args);
         }
     }

MessageEntry.cs

3、新建文件Messages.xml，用以配置要生成的信息：

 <?xml version="1.0" encoding="utf-8" ?>
 <messages>
     <message id="MandatoryField" value="The {0} is mandatory." category="Validation"/>
     <message id="GreaterThan" value="The {0} must be greater than {1}." category="Validation"/>
     <message id="ReallyDelete" value="Do you really want to delete the {0}." category="Confirmation"/>
     <message id="UserInfo" value="Do you really want to delete the {0}." category="UserItemInfo"/>
 </messages>

Messages.xml

4、修改Messages.tt文件如下：

 <#@template debug="false" hostspecific="true" language="C#"#>
 <#@assembly name="System.Core.dll"#>
 <#@assembly name="System.Xml"#>
 <#@import namespace="System"#>
 <#@import namespace="System.Xml"#>
 <#@import namespace="System.Linq"#>
 <#@output extension=".cs" #>
 namespace MessageCodeGenrator
 {
     using System;
     public static class Messages
     {
         <# XmlDocument messageDoc = new XmlDocument();
             messageDoc.Load(this.Host.ResolvePath("Messages.xml"));
             var messageEntries = messageDoc.GetElementsByTagName("message").Cast<XmlElement>();
             var categories = (from element in messageEntries
                             select element.Attributes["category"].Value).Distinct();
             foreach (var category in categories)
             {#>

         public static class <#=  category#>
         {
             <#
             foreach (var element in messageDoc.GetElementsByTagName("message").Cast<XmlElement>().Where(element => element.Attributes["category"].Value == category))
             {
                 string id = element.Attributes["id"].Value;
                 string value = element.Attributes["value"].Value;
                 string categotry = element.Attributes["category"].Value;
             #>

             public static MessageEntry <#= id #> = new MessageEntry("<#= id #>","<#= value#>","<#= categotry#>");
         <#}#>
 }
     <#}#>
 }
 }

Messages.tt

5、右键点击Messages.tt，选择运行自定义工具，如下：

6、执行完后，查看Messages.cs文件，可以看到已经生成了所需要的代码：

 namespace MessageCodeGenrator
 {
     using System;
     public static class Messages
     {

         public static class Validation
         {

             public static MessageEntry MandatoryField = new MessageEntry("MandatoryField","The {0} is mandatory.","Validation");

             public static MessageEntry GreaterThan = new MessageEntry("GreaterThan","The {0} must be greater than {1}.","Validation");
         }

         public static class Confirmation
         {

             public static MessageEntry ReallyDelete = new MessageEntry("ReallyDelete","Do you really want to delete the {0}.","Confirmation");
         }

         public static class UserItemInfo
         {

             public static MessageEntry UserInfo = new MessageEntry("UserInfo","Do you really want to delete the {0}.","UserItemInfo");
         }
     }
 }

Messages.cs