一个简单的代码生成器（T4文本模板运用）

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T4文本模板转换过程）；

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<EntityClassPropertyInfo> ropertyListTemp = new List<EntityClassPropertyInfo>();

            foreach (DataColumn dcol in dt.Columns)

            {

                ropertyListTemp.Add(new EntityClassPropertyInfo(dcol));

            }

            this.RopertyList = ropertyListTemp;

            List<EntityClassPropertyInfo> primaryKeyListTemp = new List<EntityClassPropertyInfo>();

            List<EntityClassPropertyInfo> notPrimaryKeyListTemp = new List<EntityClassPropertyInfo>(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<EntityClassPropertyInfo> RopertyList

        {

            get;

            private set;

        }

        public List<EntityClassPropertyInfo> PrimaryKeyList

        {

            get;

            private set;

        }

        public List<EntityClassPropertyInfo> 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;

/// <summary>

/// <#= entity.ClassName#> 的摘要说明

/// </summary>

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;

/// <summary>

/// <#= entity.ClassName#> 的摘要说明

/// </summary>

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<MySqlParameter> parameterList = new List<MySqlParameter>();

<#  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<string> propertyNameList= new List<string>();

        foreach(EntityClassPropertyInfo property in entity.RopertyList)

        {

            propertyNameList.Add(property.PropertyName);

        }

        return propertyNameList.ToArray();

    }

    private string[] GetSqlInsertValue()

    {

        List<string> propertyNameList= new List<string>();

        foreach(EntityClassPropertyInfo property in entity.RopertyList)

        {

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

        }

        return propertyNameList.ToArray();

    }

    private string[] GetSqlDelVariable()

    {

        List<string> propertyList= new List<string>();

        foreach(EntityClassPropertyInfo property in entity.PrimaryKeyList)

        {

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

        }

        return propertyList.ToArray();

    }

    private string[] GetSqlDelParameter()

    {

        List<string> propertyList= new List<string>();

        foreach(EntityClassPropertyInfo property in entity.PrimaryKeyList)

        {

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

        }

        return propertyList.ToArray();

    }

    private string[] GetSqlUpdateSet()

    {

        List<string> propertyList= new List<string>();

        foreach(EntityClassPropertyInfo property in entity.NotPrimaryKeyList)

        {

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

        }

        return propertyList.ToArray();

    }

    private string[] GetSqlWhereId()

    {

        List<string> propertyList= new List<string>();

        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）：一个简单的代码生成器（T4文本模板运用）