public class RandomGet<T>
        {
            private class RandomModel
            {
                public T Value { get; set; }
                public RandomModel Next { get; set; }
            }
            public RandomGet(params T[] value)
            {
                if (value != null)
                {
                    foreach (var item in value)
                    {
                        AllObject.Add(new RandomModel() { Value =http://www.mamicode.com/ item });
                    }
                }
                if (AllObject.Count > 0)
                {
                    //创建链表
                    AllObject[AllObject.Count - 1].Next = AllObject[0];
                    for (int i = 0; i < AllObject.Count - 1; i++)
                    {
                        AllObject[i].Next = AllObject[i + 1];
                    }
                    Current = AllObject[0];
                }
                else
                {
                    throw new ArgumentException("");
                }
            }
            private List<RandomModel> AllObject { get; set; } = new List<RandomModel>();
            private RandomModel Current;
            public T GetValue()
            {
                Current = Current.Next; //超高的并发，可能短暂的无法切换，但是也会实现数据库的切换
                return Current.Value;
            }

        }

public class BreakAwayContext : DbContext
        {
            /// <summary>
            /// 命令拦截器
            /// </summary>
            public class NoLockInterceptor : DbCommandInterceptor
            {
                public override void ScalarExecuting(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
                {
                    command.Connection.Close(); //这里的Close不会大量关闭Connection，因为C#自己的连接池机制，这里不会关闭连接
                    command.Connection.ConnectionString = SelectModel.GetValue();
                    command.Connection.Open();

                }

                public override void ReaderExecuting(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
                {
                    command.Connection.Close();
                    command.Connection.ConnectionString = SelectModel.GetValue();
                    command.Connection.Open();
                }
            }
            static BreakAwayContext()
            {
                System.Data.Entity.Infrastructure.Interception.DbInterception.Add(new NoLockInterceptor()); //关键代码，设置拦截器
            }
            static RandomGet<String> InsertModel = new RandomGet<String>("Data Source=192.168.0.150;Initial Catalog=MyBook;user id=root;password=123123;");//修改删除的字符串
            static RandomGet<String> SelectModel = new RandomGet<String>(
                "Data Source=192.168.0.150;Initial Catalog=MyBook;user id=root;password=123123;"
                , "Data Source=192.168.0.150;Initial Catalog=MyBook;user id=root;password=123123;"
                , "Data Source=192.168.0.150;Initial Catalog=MyBook;user id=root;password=123123;");//查询的字符串
            public BreakAwayContext()
                : base(InsertModel.GetValue()) //这里每个EF对象创建的时候，调用这个，获得一个连接字符串
            {
            }           

            public DbSet<Destination> Destinations { get; set; }
        }