CodeSmith 使用教程(17) Merge策略

梦里梦外; 2023-10-16 19:08 66阅读 0赞

前面介绍了CodeSmith使用的基本用法，通过代码模板来生成代码，但如果你修改了自动生成的代码，再次使用代码模板生成代码后，你修改的代码也就丢失了，CodeSmith 支持多种“合并（Merge）”来解决这个问题，以保留你自己修该过的部分。

CodeSmith支持如下三种“合并策略”：

*  [InsertRegion Merge ][InsertRegion Merge]策略
 *  [PreserveRegions Merge策略][PreserveRegions Merge]
 *  [InsertClass Merge ][InsertClass Merge]策略

不过这些策略主要是针对C\#，VB这些支持Region的语言，对于其它语言可能就需要使用其它方法，比如自定义Merge策略，CodeSmith允许通过[CodeSmith.Engine.IMergeStrategy][] 来扩展“合并”策略，本人推荐CodeSmith的一个原因就是CodeSmith提供了很多接口而不仅仅是一个工具，比如除了CodeSmith支持的属性，XML属性，你也可以通过 CodeSmith.CustomProperties来自定义属性种类，除了CodeSmith支持的数据源种类（MySQL，Oracle），你也可以通过自定义的Schema Provider 支持新的数据库类型或是其它数据类型。

InsertRegion策略

InsertRegion 顾名思义，就是在源码中定义一个Region，然后让CodeSmith自动生成的代码只插入到该区域，而在区域外的代码CodeSmith不会去碰它们，从而实现了自定义的代码和自动生成代码的合并。

PreserveRegion策略

PreserveRegion 是定义多个区域，然后通知CodeSmith保持这些区域代码不变，自动创建的代码添加到这些区域的外面，和InsertRegion作用相反。

下面还是借用CodeSmith 自带的Merge示例说明一下这两种策略的基本用法：

首先是InsertRegion策略，定义一个类文件InsertRegionSample.cs

**\[csharp\]** [ view plain][view plain] [copy][view plain] [print][view plain] [?][view plain]

1.  public class InsertRegionsSample
2.  \{
3.  
4.  public void SomeCustomMethod()
5.  \{
6.  // This is my custom code that I want to preserve.
7.  // I can make changes to it and my changes will
8.  // not be overwritten.
9.  \}
10. 
11.  \#region Sample Generated Region
12. // This region generated by CodeSmith on Saturday, 12 January 2013
13.  \#endregion
14. \}

public class InsertRegionsSample
    {
    
        public void SomeCustomMethod()
    	{
            // This is my custom code that I want to preserve.
            // I can make changes to it and my changes will
            // not be overwritten.
    	}
    
    	#region Sample Generated Region
    // This region generated by CodeSmith on Saturday, 12 January 2013
    	#endregion
    }

其中定义了一个Region，名为Sample Generated Region ，准备让CodeSmith查入代码，编写一个简单的代码模板，插入当前时间：

**\[csharp\]** [ view plain][view plain] [copy][view plain] [print][view plain] [?][view plain]

1.  <%@ Template Language="C\#" TargetLanguage="C\#" Description="Demonstrates using an InsertRegion merge strategy in C\#." %>
2.  // This region generated by CodeSmith on <%= DateTime.Now.ToLongDateString() %>

<%@ Template Language="C#" TargetLanguage="C#"   Description="Demonstrates using an InsertRegion merge strategy in C#." %>
    // This region generated by CodeSmith on <%= DateTime.Now.ToLongDateString() %>

然后通过CodeSmith项目为模板设置Merge策略：

[![20130112002][]][20130112002 1]

选择InsertRegion策略， 然后设置要插入的RegionName。

生成后的代码如下：

**\[csharp\]** [ view plain][view plain] [copy][view plain] [print][view plain] [?][view plain]

可以看到CodeSmith只在Region 处插入代码，而该Region外的部分保持不变。

类似的PreserveRegions策略，代码和模板定义如下：  
PreserveRegionsSample.cs

**\[csharp\]** [ view plain][view plain] [copy][view plain] [print][view plain] [?][view plain]

1.  public class PreserveRegionsSample
2.  \{
3.  
4.  \#region "Custom Region 1"
5.  
6.  // This is a place holder for your custom code.
7.  // It must exist so that CodeSmith knows where
8.  // to put the custom code that will be parsed
9.  // from the target source file.
10. // The region name is used to match up the regions
11. // and determine where each region of custom code
12. // should be inserted into the merge result.
13. 
14. \#endregion
15. 
16. public void SomeGeneratedMethod()
17. \{
18. 
19. // This section and all other non-custom code
20. // regions will be overwritten during each
21. // template execution.
22. // Current Date: Saturday, 12 January 2013
23. \}
24. 
25. \#region "Custom Region 2"
26. 
27. // The contents of this region will also be preserved
28. // during generation.
29. 
30. \#endregion
31. 
32. \}

public class PreserveRegionsSample
    {
    
    #region "Custom Region 1"
    
    	// This is a place holder for your custom code.
    	// It must exist so that CodeSmith knows where
    	// to put the custom code that will be parsed
    	// from the target source file.
    	// The region name is used to match up the regions
    	// and determine where each region of custom code
    	// should be inserted into the merge result.
    
    #endregion
    
        public void SomeGeneratedMethod()
    	{
    
            // This section and all other non-custom code
            // regions will be overwritten during each
            // template execution.
            // Current Date: Saturday, 12 January 2013
    	}
    
    #region "Custom Region 2"
    
        // The contents of this region will also be preserved
        // during generation.
    
    #endregion
    
    }

模板定义如下：

**\[csharp\]** [ view plain][view plain] [copy][view plain] [print][view plain] [?][view plain]

1.  <%@ Template Language="C\#" TargetLanguage="C\#" Description="Demonstrates using a PreserveRegions merge strategy in C\#." %>
2.  public class PreserveRegionsSample
3.  \{
4.  
5.  \#region "Custom Region 1"
6.  
7.  // This is a place holder for your custom code.
8.  // It must exist so that CodeSmith knows where
9.  // to put the custom code that will be parsed
10. // from the target source file.
11. // The region name is used to match up the regions
12. // and determine where each region of custom code
13. // should be inserted into the merge result.
14. 
15. \#endregion
16. 
17. public void SomeGeneratedMethod()
18. \{
19. 
20. // This section and all other non-custom code
21. // regions will be overwritten during each
22. // template execution.
23. // Current Date: <%= DateTime.Now.ToLongDateString() %>
24. \}
25. 
26. \#region "Custom Region 2"
27. 
28. // The contents of this region will also be preserved
29. // during generation.
30. 
31. \#endregion
32. 
33. \}

<%@ Template Language="C#" TargetLanguage="C#"    Description="Demonstrates using a PreserveRegions merge strategy in C#." %>
    public class PreserveRegionsSample
    {
    
    #region "Custom Region 1"
    
    	// This is a place holder for your custom code.
    	// It must exist so that CodeSmith knows where
    	// to put the custom code that will be parsed
    	// from the target source file.
    	// The region name is used to match up the regions
    	// and determine where each region of custom code
    	// should be inserted into the merge result.
    
    #endregion
    
        public void SomeGeneratedMethod()
    	{
    
            // This section and all other non-custom code
            // regions will be overwritten during each
            // template execution.
            // Current Date: <%= DateTime.Now.ToLongDateString() %>
    	}
    
    #region "Custom Region 2"
    
        // The contents of this region will also be preserved
        // during generation.
    
    #endregion
    
    }

模板中也定义了两个区域，然后为该模板设置Merge策略，使用PreserveRegion时可能有多个Region需要保留，因此可以使用RegX来定义要保留的Region：  
[![20130112003][]][20130112003 1]

本例[下载][Link 1]

InsertClass 策略用在给以重载的代码中插入自动生成的代码,挺起来和InsertRegion功能很类似，的确也是如此，但InsertClass支持更多的配置，可以实现更加灵活和强大的功能。

它支持的配置有：

<table style="margin:0px 0px 18px; padding:0px; border:1px solid rgb(221,221,221); color:rgb(85,85,85); line-height:21px; font-family:'Times New Roman',Helvetica,serif; font-size:14px; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:baseline; border-collapse:collapse; border-spacing:0px"> 
 <tbody style="font:inherit; margin:0px; padding:0px; border:0px currentColor; vertical-align:baseline"> 
  <tr style="font:inherit; margin:0px; padding:0px; border:0px currentColor; vertical-align:baseline"> 
   <th style="font:inherit; margin:0px; padding:0px 10px 10px 0px; border:0px currentColor; vertical-align:baseline"> <p style="border:0px currentColor; text-align:left; line-height:26px; padding-top:0px; padding-bottom:0px; clear:none; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; margin-top:0px; margin-bottom:10px; vertical-align:baseline"> Language</p> </th> 
   <th style="font:inherit; margin:0px; padding:0px 10px 10px 0px; border:0px currentColor; vertical-align:baseline"> String, Required</th> 
   <th style="font:inherit; margin:0px; padding:0px 10px 10px 0px; border:0px currentColor; vertical-align:baseline"> <p style="border:0px currentColor; text-align:left; line-height:26px; padding-top:0px; padding-bottom:0px; clear:none; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; margin-top:0px; margin-bottom:10px; vertical-align:baseline"> 只支持VB和C#</p> </th> 
  </tr> 
  <tr style="font:inherit; margin:0px; padding:0px; border:0px currentColor; vertical-align:baseline; background-color:rgb(249,249,249)"> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> ClassName</td> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> String, Required</td> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> 需插入代码的类名.</td> 
  </tr> 
  <tr style="font:inherit; margin:0px; padding:0px; border:0px currentColor; vertical-align:baseline"> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> PreserveClassAttributes</td> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> Boolean, defaults to False</td> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> 是否保留类已有的Attributes，缺省CodeSmith替代类原来的Attributes</td> 
  </tr> 
  <tr style="font:inherit; margin:0px; padding:0px; border:0px currentColor; vertical-align:baseline; background-color:rgb(249,249,249)"> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> OnlyInsertMatchingClass</td> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> Boolean, defaults to False</td> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> 是否只插入匹配的类定义中</td> 
  </tr> 
  <tr style="font:inherit; margin:0px; padding:0px; border:0px currentColor; vertical-align:baseline"> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> MergeImports</td> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> Boolean, defaults to False</td> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> 是否合并Import语句</td> 
  </tr> 
  <tr style="font:inherit; margin:0px; padding:0px; border:0px currentColor; vertical-align:baseline; background-color:rgb(249,249,249)"> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> NotFoundAction</td> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> Enum, defaults to None</td> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> 如果指定的类没找到后的行动，可以None,InsertAtBottom，InsertInParent几种选项</td> 
  </tr> 
  <tr style="font:inherit; margin:0px; padding:0px; border:0px currentColor; vertical-align:baseline"> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> NotFoundParent</td> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> String, no default</td> 
   <td style="margin:0px; padding:9px 10px; border:currentColor; color:rgb(51,51,51); line-height:18px; font-family:inherit; font-size:undefined; font-style:inherit; font-variant:inherit; font-weight:inherit; vertical-align:top"> 如果指定NotFoundAction为InsertInParent对应的父类名称.</td> 
  </tr> 
 </tbody> 
</table>

比如使用如下配置：

Language: C\#  
ClassName: “Pet”  
PreserveClassAttributes: True  
OnlyInsertMatchingClass: True  
MergeImports: True

现有类定义：

**\[csharp\]** [ view plain][view plain] [copy][view plain] [print][view plain] [?][view plain]

1.  using System;
2.  using System.ComponentModel.DataAnnotations;
3.  namespace Petshop
4.  \{
5.  \[ScaffoldTable(true)\]
6.  public class Pet
7.  \{
8.  public int Age \{ get; set; \}
9.  public string FirstName \{ get; set; \}
10. public string LastName \{ get; set; \}
11. \}
12. \}

using System;
    using System.ComponentModel.DataAnnotations;
    namespace Petshop
    {
        [ScaffoldTable(true)]
        public class Pet
        {
            public int Age { get; set; }
            public string FirstName { get; set; }
            public string LastName { get; set; }
        }
    }

自动生成的代码如下：

**\[csharp\]** [ view plain][view plain] [copy][view plain] [print][view plain] [?][view plain]

1.  using System;
2.  using System.Text;
3.  namespace Petshop
4.  \{
5.  public class Pet
6.  \{
7.  public string FirstName \{ get; set; \}
8.  
9.  public string LastName \{ get; set; \}
10. 
11. public string FullName
12. \{
13. get \{ return String.Format("\{0\} \{1\}", FirstName, LastName); \}
14. 
15. \}
16. \}
17. \}

using System;
    using System.Text;
    namespace Petshop
    {
        public class Pet
        {
            public string FirstName { get; set; }
    
            public string LastName { get; set; }
    
            public string FullName
            {
                get { return String.Format("{0} {1}", FirstName, LastName); }
    
            }
        }
    }

使用InsertClass 合并后的代码如下：

**\[csharp\]** [ view plain][view plain] [copy][view plain] [print][view plain] [?][view plain]

1.  using System;
2.  using System.ComponentModel.DataAnnotations;
3.  using System.Text;
4.  namespace Petshop
5.  \{
6.  \[ScaffoldTable(true)\]
7.  public class Pet
8.  \{
9.  public string FirstName \{ get; set; \}
10. 
11. public string LastName \{ get; set; \}
12. 
13. public string FullName
14. \{
15. get \{ return String.Format("\{0\} \{1\}", FirstName, LastName); \}
16. 
17. \}
18. \}
19. \}

[InsertRegion Merge]: http://docs.codesmithtools.com/display/Generator/InsertRegion+Merge+Strategy
[PreserveRegions Merge]: http://docs.codesmithtools.com/display/Generator/PreserveRegions+Merge+Strategy
[InsertClass Merge]: http://docs.codesmithtools.com/display/Generator/InsertClass+Merge+Strategy
[CodeSmith.Engine.IMergeStrategy]: http://codesmithtools.com/help/##GeneratorAPI.chm/html/4a67e55e-e98f-d1c5-3bd7-ad923a6e2147.htm
[view plain]: http://blog.csdn.net/mapdigit/article/details/8575107#
[20130112002]: http://www.imobilebbs.com/wordpress/wp-content/uploads/2013/01/20130112002.png
[20130112002 1]: http://www.imobilebbs.com/wordpress/archives/4271/attachment/20130112002
[20130112003]: http://www.imobilebbs.com/wordpress/wp-content/uploads/2013/01/20130112003.png
[20130112003 1]: http://www.imobilebbs.com/wordpress/archives/4271/attachment/20130112003
[Link 1]: http://www.imobilebbs.com/download/codesmith/MergeDemo.zip