说要写这篇文章有一段时间了，但因为最近各方面的压力导致心情十二分的不好，下班后往往都洗洗睡了。今天痛定思痛，终于把这件拖了很久的事做了。好,不废话了,现在看看"一个简单的代码生成器" .

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先看看界面吧！

简约到如此,说是代码生成器,估计是要被吐槽的。好吧，借用园子里博友的说法，这只是一粒粟子，如果你愿意，你能看到代码生成器的“种子”。

这样运行的！

画了个简图已描述这个简单的代码生成器的工作过程。下面的介绍将以此图展开：

1）读取数据表的信息：从数据库中读取数据表的信息并转换成要为T4文本模板引擎提供的数据（EntityClassInfo）;

2）将要为T4文本模板引擎提供的数据（EntityClassInfo）作为参数传递给T4文本模板引擎（其实是T4文本模板引擎的宿主，详见）；

3）T4文本模板引擎读取模板；

4）T4文本模板引擎将生成的文本返回给应用程序。

 

代码：

一、在应用程序和代码中传递的参数的类型

1）EntityClassInfo.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Data;

namespace EntityInfo

{

[Serializable]

public class EntityClassInfo

{

public EntityClassInfo(DataTable dt)

{

this.ClassName = dt.TableName;

List
      
        ropertyListTemp = new List
       
        ();
       
      

foreach (DataColumn dcol in dt.Columns)

{

ropertyListTemp.Add(new EntityClassPropertyInfo(dcol));

}

this.RopertyList = ropertyListTemp;

List
      
        primaryKeyListTemp = new List
       
        ();
       
      

List
      
        notPrimaryKeyListTemp = new List
       
        (ropertyListTemp);
       
      

foreach (DataColumn dcol in dt.PrimaryKey)

{

primaryKeyListTemp.Add(new EntityClassPropertyInfo(dcol));

notPrimaryKeyListTemp.Remove(new EntityClassPropertyInfo(dcol));

}

this.PrimaryKeyList = primaryKeyListTemp;

this.NotPrimaryKeyList = notPrimaryKeyListTemp;

}

public string ClassName

{

get;

private set;

}

public List
      
        RopertyList
      

{

get;

private set;

}

public List
      
        PrimaryKeyList
      

{

get;

private set;

}

public List
      
        NotPrimaryKeyList
      

{

get;

private set;

}

}

}

2）EntityClassPropertyInfo.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Data;

namespace EntityInfo

{

[Serializable]

public class EntityClassPropertyInfo

{

public EntityClassPropertyInfo(DataColumn dcol)

{

this.PropertyName = dcol.ColumnName;

this.PropertyType = dcol.DataType.Name;

this.IsValueType = false;

if (dcol.DataType.IsValueType)

{

if (dcol.AllowDBNull)

{

this.PropertyType = this.PropertyType + "?";

}

else

{

this.IsValueType = true;

}

}

}

public string PropertyName

{

get;

private set;

}

public string PropertyType

{

get;

private set;

}

public bool IsValueType

{

get;

private set;

}

public override bool Equals(object obj)

{

EntityClassPropertyInfo temp = obj as EntityClassPropertyInfo;

if (this.PropertyName == temp.PropertyName && this.PropertyType == temp.PropertyType)

{

return true;

}

return false;

}

}

}

二、模板

1）生成实体类的模板：Entity.tt

<#@ template debug="false" hostspecific="false" language="C#" #>

<#@ output extension=".txt" #>

<#@ import namespace="EntityInfo" #>

<#@ parameter type="EntityInfo.EntityClassInfo" name="entity" #>

using System;

using System.Data;

using System.Configuration;

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;

/// 

/// <#= entity.ClassName#> 的摘要说明

/// 

public class <#= entity.ClassName#>

{

public <#= entity.ClassName#>()

{

//

// TODO: 在此处添加构造函数逻辑

//

}

<#  foreach(EntityClassPropertyInfo property in entity.RopertyList)

{ #>

private <#= property.PropertyType#> m_<#= property.PropertyName#>;

<#;

}

#>

<#  foreach(EntityClassPropertyInfo property in entity.RopertyList)

{ #>

public  <#= property.PropertyType#>  <#= property.PropertyName#>

{

set { m_<#= property.PropertyName#> = value; }

get { return m_<#= property.PropertyName#>; }

}

<#;

}

#>

}

2）生成DAL层的模板：DataAccess.tt

<#@ template debug="false" hostspecific="false" language="C#" #>

<#@ output extension=".txt" #>

<#@ import namespace="EntityInfo" #>

<#@ import namespace="System.Collections.Generic" #>

<#@ parameter type="EntityInfo.EntityClassInfo" name="entity" #>

using System;

using System.Data;

using System.Configuration;

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 MySql.Data.MySqlClient;

using System.Collections.Generic;

/// 

/// <#= entity.ClassName#> 的摘要说明

/// 

public class <#= entity.ClassName#>DAL

{

public <#= entity.ClassName#>DAL()

{

}

#region 私有方法

#region 根据实体类获取MySqlParameter数组 +MySqlParameter[] FromModel(<#= entity.ClassName#> model)

private static MySqlParameter[] FromModel(<#= entity.ClassName#> model)

{

List
      
        parameterList = new List
       
        ();
       
      

<#  foreach(EntityClassPropertyInfo property in entity.RopertyList)

{

#>        parameterList.Add(new MySqlParameter("@<#=property.PropertyName#>", SQLHelper.ToDBValue(model.<#=property.PropertyName#>)));

<#;

}

#>

return parameterList.ToArray();

}

#endregion

#region 将dr中的数据转换为实体类对象 + <#= entity.ClassName#> ToModel(DataRow dr)

private static <#= entity.ClassName#> ToModel(DataRow dr)

{

<#= entity.ClassName#> model = new <#= entity.ClassName#>();

<#  foreach(EntityClassPropertyInfo property in entity.RopertyList)

{

if(property.IsValueType)

{

#>        model.<#=property.PropertyName#> = Convert.To<#= property.PropertyType#>(SQLHelper.FromDBValue(dr["<#= property.PropertyName #>"]));

<#;

}

else

{

#>        model.<#=property.PropertyName#> = SQLHelper.FromDBValue(dr["<#=property.PropertyName#>"]) as <#=property.PropertyType#>;

<#;

}

}

#>

return model;

}

#endregion

#endregion

#region 增 + int Insert(<#= entity.ClassName#> model)

public static int Insert(<#= entity.ClassName#> model)

{

int result = -1;

string sql = @"INSERT INTO <#= entity.ClassName#>(<#= string.Join(",",GetSqlInsertInto()) #>)

VALUES(<#= string.Join(",",GetSqlInsertValue()) #>);";

result = SQLHelper.ExecuteNonQuery(sql,FromModel(model));

return result;

}

#endregion

#region 删 + int DeleteById(<#= string.Join(",",GetSqlDelVariable()) #>)

public static int DeleteById(<#= string.Join(",",GetSqlDelVariable()) #>)

{

int result = -1;

string sql = @"DELETE FROM <#= entity.ClassName#> WHERE <#= string.Join(" AND ",GetSqlWhereId()) #>;";

result = SQLHelper.ExecuteNonQuery(sql,<#= string.Join(",",GetSqlDelParameter()) #>);

return result;

}

#endregion

#region 改 + int Update(<#= entity.ClassName#> model)

public static int Update(<#= entity.ClassName#> model)

{

int result = -1;

string sql = @"UPDATE <#= entity.ClassName#>

SET <#= string.Join(",",GetSqlUpdateSet()) #>

WHERE <#= string.Join(" AND ",GetSqlWhereId()) #>";

result = SQLHelper.ExecuteNonQuery(sql, FromModel(model));

return result;

}

#endregion

#region 查 + int GetCountAll()

public static int GetCountAll()

{

int result = 0;

string sql = @"SELECT Count(*) FROM <#= entity.ClassName#>;";

result = Convert.ToInt32(SQLHelper.ExecuteScalar(sql));

return result;

}

#endregion

#region 查 + List<<#= entity.ClassName#>> GetBySql(string sql,params MySqlParameter[] parameters)

public static List<<#= entity.ClassName#>> GetBySql(string sql,params MySqlParameter[] parameters)

{

List<<#= entity.ClassName#>> modelList = new List<<#= entity.ClassName#>>();

DataTable dt = SQLHelper.ExecuteDataTable(sql,parameters);

foreach (DataRow dr in dt.Rows)

{

modelList.Add(ToModel(dr));

}

return modelList;

}

#endregion

}

<#+

private string[] GetSqlInsertInto()

{

List
      
        propertyNameList= new List
       
        ();
       
      

foreach(EntityClassPropertyInfo property in entity.RopertyList)

{

propertyNameList.Add(property.PropertyName);

}

return propertyNameList.ToArray();

}

private string[] GetSqlInsertValue()

{

List
      
        propertyNameList= new List
       
        ();
       
      

foreach(EntityClassPropertyInfo property in entity.RopertyList)

{

propertyNameList.Add("@" + property.PropertyName);

}

return propertyNameList.ToArray();

}

private string[] GetSqlDelVariable()

{

List
      
        propertyList= new List
       
        ();
       
      

foreach(EntityClassPropertyInfo property in entity.PrimaryKeyList)

{

propertyList.Add(property.PropertyType + "  m_" + property.PropertyName);

}

return propertyList.ToArray();

}

private string[] GetSqlDelParameter()

{

List
      
        propertyList= new List
       
        ();
       
      

foreach(EntityClassPropertyInfo property in entity.PrimaryKeyList)

{

propertyList.Add("new MySqlParameter(@\"" + property.PropertyName + "\" ,m_" + property.PropertyName + ")");

}

return propertyList.ToArray();

}

private string[] GetSqlUpdateSet()

{

List
      
        propertyList= new List
       
        ();
       
      

foreach(EntityClassPropertyInfo property in entity.NotPrimaryKeyList)

{

propertyList.Add(property.PropertyName +"=@" + property.PropertyName);

}

return propertyList.ToArray();

}

private string[] GetSqlWhereId()

{

List
      
        propertyList= new List
       
        ();
       
      

foreach(EntityClassPropertyInfo property in entity.PrimaryKeyList)

{

propertyList.Add(property.PropertyName +"=@" + property.PropertyName);

}

return propertyList.ToArray();

}

#>

三、代码生成四步走：

1)从数据表信息 =》EntityClassInfo：

DataTable dt = SQLHelper.ExecuteDataTable(SQLHelper.GetConnectionString(), string.Format("SELECT * FROM {0} LIMIT 0,0", cbbTableName.SelectedValue.ToString()));

EntityClassInfo entityInfo = new EntityClassInfo(dt);

备注：

#region ExecuteTable方法

public static DataTable ExecuteDataTable(string connectionString,string sql, params MySqlParameter[] parameters)

{

using (MySqlConnection conn = new MySqlConnection(connectionString))

{

using(MySqlCommand cmd = conn.CreateCommand())

{

cmd.CommandText = sql;

cmd.Parameters.AddRange(parameters);

using (MySqlDataAdapter da = new MySqlDataAdapter(cmd))

{

using (DataTable dt = new DataTable())

{

da.Fill(dt);

da.FillSchema(dt, SchemaType.Source);   //从数据源中检索架构

return dt;

}

}

}

}

}

#endregion

2）给T4文本模板传参：

CustomTextTemplatingEngineHost host = new CustomTextTemplatingEngineHost();

host.Session = new TextTemplatingSession();

host.Session.Add("entity", classInfo);

3）读取文本模板：

string input = File.ReadAllText(templatePath);

string output = new Engine().ProcessTemplate(input, host);

4）返回生成的文本：

string output = new Engine().ProcessTemplate(input, host);

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源码下载（VS2010项目）：