利用反射执行代码

项目组经常有用到反射来执行代码的，直接上代码，大家一看就明白。

    public class PrimaryKeyAttribute : Attribute
    { }
    public class DbColumnAttribute : Attribute
    {
        public string Name { get; set; }
        public DbColumnAttribute(string name)
        {
            this.Name = name;
        }
    }
    public class Client
    {
        [PrimaryKey]
        [DbColumn("client_id")]
        public int ClientId { get; set; }

        [DbColumn("last_name")]
        public string LastName { get; set; }

        [DbColumn("first_name")]
        public string FirstName { get; set; }

        [DbColumn("email")]
        public string Email { get; set; }
    }


        static void Test3()
        {
            var client = new Client() { ClientId = 2, LastName = "James", FirstName = "jon", Email = "jon@163.com" };
            WritePK<Client>(client);
            Console.WriteLine();
            WriteColumnMappings<Client>(client);
        }

        public static void WritePK<T>(T item) where T : new()
        {
            var type = item.GetType();
            var queryPts = type.GetProperties();
            Console.WriteLine("Finding PK for {0} ...", type.Name);

            var pk = queryPts.FirstOrDefault(x =>
                        x.GetCustomAttributes(false).Any(
                            a => a.GetType() == typeof(PrimaryKeyAttribute)
                        )
                    );
            if (pk != null)
            {
                string msg = "The Primary Key for the {0} class is the {1} property";
                Console.WriteLine(msg, type.Name, pk.Name);
            }
        }

        public static void WriteColumnMappings<T>(T item) where T : new()
        {
            var type = item.GetType();
            var queryPts = type.GetProperties();
            Console.WriteLine("Finding properties for {0} ...", type.Name);

            foreach (var p in queryPts)
            {
                var attributes = p.GetCustomAttributes(false); //获取属性的特性
                var columnMapping = attributes.FirstOrDefault(a =>
                                        a.GetType() == typeof(DbColumnAttribute)
                                    );
                if (columnMapping != null)
                {
                    string msg = "the {0} property maps to the {1} database column";
                    var mapsto = columnMapping as DbColumnAttribute;
                    Console.WriteLine(msg, p.Name, mapsto.Name);
                }
            }
        }