ASP.NET中实现根据匿名类、datatable、sql生成实体类

在开发中可能会遇到这几种情况：

1、EF或LINQ查询出来的匿名对象在其它地方调用不方便，又懒的手动建实体类

2、通过datatable反射实体需要先建一个类 ，头痛

3、通过SQL语句返回的实体也需要先建一个类 ，头痛

4、如果通过代码生成器要写模版，需要安装或者不想生成一堆不用的类 
 
为了解决上面的不便之处，我封装了一个实体生成类，可以扔到程序里面任意调用

封装类：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Text.RegularExpressions;

namespace SyntacticSugar
{
  /// <summary>
  /// ** 描述：实体生成类
  /// ** 创始时间：2015-4-17
  /// ** 修改时间：-
  /// ** 作者：sunkaixuan
  /// ** qq：610262374 欢迎交流,共同提高 ,命名语法等写的不好的地方欢迎大家的给出宝贵建议
  /// </summary>
  public class ClassGenerating
  {
    /// <summary>
    /// 根据匿名类获取实体类的字符串
    /// </summary>
    /// <param name="entity">匿名对象</param>
    /// <param name="className">生成的类名</param>
    /// <returns></returns>
    public static string DynamicToClass(object entity, string className)
    {
      StringBuilder reval = new StringBuilder();
      StringBuilder propertiesValue = new StringBuilder();
      var propertiesObj = entity.GetType().GetProperties();
      string replaceGuid = Guid.NewGuid().ToString();
      string nullable = string.Empty;
      foreach (var r in propertiesObj)
      {

        var type = r.PropertyType;
        if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>))
        {
          type = type.GetGenericArguments()[0];
          nullable = "?";
        }
        if (!type.Namespace.Contains("System.Collections.Generic"))
        {
          propertiesValue.AppendLine();
          string typeName = ChangeType(type);
          propertiesValue.AppendFormat("public {0}{3} {1} {2}", typeName, r.Name, "{get;set;}", nullable);
          propertiesValue.AppendLine();
        }
      }

      reval.AppendFormat(@"
         public class {0}{{
            {1}
         }}
      ", className, propertiesValue);

      return reval.ToString();
    }

    /// <summary>
    /// 根据DataTable获取实体类的字符串
    /// </summary>
    /// <param name="sql"></param>
    /// <param name="className"></param>
    /// <returns></returns>
    public static string DataTableToClass(DataTable dt, string className)
    {
      StringBuilder reval = new StringBuilder();
      StringBuilder propertiesValue = new StringBuilder();
      string replaceGuid = Guid.NewGuid().ToString();
      foreach (DataColumn r in dt.Columns)
      {
        propertiesValue.AppendLine();
        string typeName = ChangeType(r.DataType);
        propertiesValue.AppendFormat("public {0} {1} {2}", typeName, r.ColumnName, "{get;set;}");
        propertiesValue.AppendLine();
      }
      reval.AppendFormat(@"
         public class {0}{{
            {1}
         }}
      ", className, propertiesValue);

      return reval.ToString();
    }

    /// <summary>
    /// 根据SQL语句获取实体类的字符串
    /// </summary>
    /// <param name="sql">SQL语句</param>
    /// <param name="className">生成的类名</param>
    /// <param name="server">服务名</param>
    /// <param name="database">数据库名称</param>
    /// <param name="uid">账号</param>
    /// <param name="pwd">密码</param>
    /// <returns></returns>
    public static string SqlToClass(string sql, string className, string server, string database, string uid, string pwd)
    {
      using (SqlConnection conn = new SqlConnection(string.Format("server={0};uid={2};pwd={3};database={1}", server, database, uid, pwd)))
      {
        SqlCommand command = new SqlCommand();
        command.Connection = conn;
        command.CommandText = sql;
        DataTable dt = new DataTable();
        SqlDataAdapter sad = new SqlDataAdapter(command);
        sad.Fill(dt);
        var reval = DataTableToClass(dt, className);
        return reval;
      }
    }
    /// <summary>
    /// 根据SQL语句获取实体类的字符串
    /// </summary>
    /// <param name="sql">SQL语句</param>
    /// <param name="className">生成的类名</param>
    /// <param name="connName">webconfig的connectionStrings name</param>
    /// <returns></returns>
    public static string SqlToClass(string sql, string className, string connName)
    {
      string connstr = System.Configuration.ConfigurationManager.ConnectionStrings[connName].ToString();
      if (connstr.Contains("metadata"))//ef
        connstr = Regex.Match(connstr, @"connection string\=""(.+)""").Groups[1].Value;
      using (SqlConnection conn = new SqlConnection(connstr))
      {
        SqlCommand command = new SqlCommand();
        command.Connection = conn;
        command.CommandText = sql;
        DataTable dt = new DataTable();
        SqlDataAdapter sad = new SqlDataAdapter(command);
        sad.Fill(dt);
        var reval = DataTableToClass(dt, className);
        return reval;
      }
    }
    /// <summary>
    /// 匹配类型
    /// </summary>
    /// <param name="type"></param>
    /// <returns></returns>
    private static string ChangeType(Type type)
    {
      string typeName = type.Name;
      switch (typeName)
      {
        case "Int32": typeName = "int"; break;
        case "String": typeName = "string"; break;
      }
      return typeName;
    }
  }
}

调用如下：

//通过匿名对象生成实体类
      var dynamicObj = new { id = 1, name = "小名", entity = new enityt1() };
      //注意：只能是单个实体不能传入 List<T> ,集合需要  List[0]
      string classCode = ClassGenerating.DynamicToClass(dynamicObj, "classDynamic");

      //通过datatable生成实体类
      DataTable dt = new DataTable();
      dt.Columns.Add("Id", typeof(int));
      dt.Columns.Add("Name");

      classCode = ClassGenerating.DataTableToClass(dt, "classTatabale");

      //通过sql语句生成实体类
      classCode = ClassGenerating.SqlToClass("select * from note", "Note", "127.0.0.1", "MyWork", "sa", "sasa");
      classCode = ClassGenerating.SqlToClass("select * from dbo.AccessoriesDetail", "AccessoriesDetail", "NFDEntities");//通过 config connstring名称

然后在调试状态把你需要的结果CTRL+C 然后去新建一个类CTRL+V