[原]强大的数据库访问类dbhelper 1.0，欢迎拍砖

优点：

1、强大的查询公用方法，如支持返回泛型实体对象集合，泛型值类型集合，实体对象，数据集等。

2、所有方法都支持参数化与非参数化访问db，调用十分方便。

3、使用了线程本地存储，使之能支持在业务逻辑层显式控制事务。

4、注释较为详细，方法较为简洁(加上注释总共200多行代码)。
5、开源，容易修改。

 

缺点：

暂时仅支持sqlserver数据库。

 

源代码：

View Code

public   class  SqlHelper
    {
         public   string  connectionString  =  System.Configuration.ConfigurationManager.AppSettings[ " ConnectionString " ];
         private  SqlConnection _connection;
         public  SqlConnection connection
        {
             get  {  return  _connection; }
             set  { _connection  =  value; }
        }
         private  SqlTransaction _transaction;
         public  SqlTransaction transaction
        {
             get  {  return  _transaction; }
             set  { _transaction  =  value; ;}
        }

         private  SqlHelper()
        {
        }

         ///   <summary>
         ///  如果当前线程已经存在SqlHelper则使用当前线程的SqlHelper，否则重新创建一个SqlHelper
         ///   </summary>
         ///   <returns></returns>
         public   static  SqlHelper Instance()
        {
             object  obj  =  Thread.GetData(Thread.GetNamedDataSlot( " SqlHelper " ));
             if  (obj  ==   null )
            {
                SqlHelper helper  =   new  SqlHelper();
                Thread.SetData(Thread.GetNamedDataSlot( " SqlHelper " ), helper);
                 return  helper;
            }
             return  (SqlHelper)obj;
        }

         ///   <summary>
         ///  打开数据库连接
         ///   </summary>
         public   void  OpenConnection()
        {
             if  (connection  ==   null ) connection  =   new  SqlConnection(connectionString);
             if  (connection.State  !=  ConnectionState.Open)
                connection.Open();
        }

         ///   <summary>
         ///  开启事务
         ///   </summary>
         public   void  BeginTransaction()
        {
            OpenConnection();
             if  (transaction  ==   null )
                transaction  =  connection.BeginTransaction();
        }

         ///   <summary>
         ///  提交事务 并且 释放并关闭资源
         ///   </summary>
         public   void  CommitTransaction()
        {
             if  (transaction  !=   null )
            {
                transaction.Commit();
                transaction.Dispose();
                transaction  =   null ;
                Dispose();
            }
        }

         ///   <summary>
         ///  回滚事务 并且 释放并关闭资源
         ///   </summary>
         public   void  RollbackTransaction()
        {
             if  (transaction  !=   null )
            {
                transaction.Rollback();
                transaction.Dispose();
                transaction  =   null ;
                Dispose();
            }
        }

         ///   <summary>
         ///  如果没有开启事务就自动释放资源，关闭连接，否则在提交或回滚事务的时候释放
         ///   </summary>
         public   void  Dispose()
        {
             if  (transaction  ==   null )
            {
                 if  (connection  !=   null )
                {
                    connection.Dispose();
                    connection.Close();
                    connection  =   null ;
                }
            }
        }

         private  SqlCommand CreateCommand(CommandType cmdType,  string  cmdText,  params  SqlParameter[] cmdParas)
        {
            SqlCommand mand  =  connection.CreateCommand();
            mand.CommandText  =  cmdText;
            mand.CommandType  =  cmdType;
            mand.Parameters.AddRange(cmdParas);
             if  (transaction  !=   null ) mand.Transaction  =  transaction;
             return  mand;
        }

         ///   <summary>
         ///  返回一个数据集
         ///   </summary>
         ///   <param name="cmdType"></param>
         ///   <param name="cmdText"></param>
         ///   <param name="cmdParas"></param>
         ///   <returns></returns>
         public  DataSet ExecuteDataSet(CommandType cmdType,  string  cmdText,  params  SqlParameter[] cmdParas)
        {
             try
            {
                OpenConnection();
                SqlCommand mand  =  CreateCommand(cmdType, cmdText, cmdParas);
                SqlDataAdapter data  =   new  SqlDataAdapter(mand);
                DataSet ds  =   new  DataSet();
                data.Fill(ds);
                 return  ds;
            }
             catch  (Exception ex) {  throw  ex; }
             finally  { Dispose(); }
        }

         ///   <summary>
         ///  返回受影响的行数
         ///   </summary>
         ///   <param name="cmdType"></param>
         ///   <param name="cmdText"></param>
         ///   <param name="cmdParas"></param>
         ///   <returns></returns>
         public   int  ExecuteNonQuery(CommandType cmdType,  string  cmdText,  params  SqlParameter[] cmdParas)
        {
             try
            {
                OpenConnection();
                SqlCommand mand  =  CreateCommand(cmdType, cmdText, cmdParas);
                 return  mand.ExecuteNonQuery();
            }
             catch  (Exception ex) {  throw  ex; }
             finally  { Dispose(); }
        }

         ///   <summary>
         ///  返回结果集中第一行第一列
         ///   </summary>
         ///   <param name="cmdType"></param>
         ///   <param name="cmdText"></param>
         ///   <param name="cmdParas"></param>
         ///   <returns></returns>
         public   object  ExecuteScalar(CommandType cmdType,  string  cmdText,  params  SqlParameter[] cmdParas)
        {
             try
            {
                OpenConnection();
                SqlCommand mand  =  CreateCommand(cmdType, cmdText, cmdParas);
                 return  mand.ExecuteScalar();
            }
             catch  (Exception ex) {  throw  ex; }
             finally  { Dispose(); }
        }

         ///   <summary>
         ///  返回泛型集合
         ///   </summary>
         ///   <typeparam name="T"></typeparam>
         ///   <param name="cmdType"></param>
         ///   <param name="cmdText"></param>
         ///   <param name="cmdParas"></param>
         ///   <returns></returns>
         public  IList < T >  ExecuteReaderList < T > (CommandType cmdType,  string  cmdText,  params  SqlParameter[] cmdParas)
        {
             try
            {
                OpenConnection();
                SqlCommand mand  =  CreateCommand(cmdType, cmdText, cmdParas);
                SqlDataReader reader  =  mand.ExecuteReader();
                IList < T >  list  =  ToList < T > (reader);
                 return  list;
            }
             catch  (Exception ex) {  throw  ex; }
             finally  { Dispose(); }
        }

         ///   <summary>
         ///  返回一个对象 如数据库无结果返回将抛出异常
         ///   </summary>
         ///   <typeparam name="T"></typeparam>
         ///   <param name="cmdType"></param>
         ///   <param name="cmdText"></param>
         ///   <param name="cmdParas"></param>
         ///   <returns></returns>
         public  T ExecuteReaderObject < T > (CommandType cmdType,  string  cmdText,  params  SqlParameter[] cmdParas)
        {
             return  ExecuteReaderList < T > (cmdType, cmdText, cmdParas)[ 0 ];
        }

         ///   <summary>
         ///  反射创建泛型集合
         ///   </summary>
         ///   <typeparam name="T"></typeparam>
         ///   <param name="reader"></param>
         ///   <returns></returns>
         private  IList < T >  ToList < T > (SqlDataReader reader)
        {
            Type type  =   typeof (T);
            IList < T >  list  =   null ;
             if  (type.IsValueType  ||  type  ==   typeof ( string ))
                list  =  CreateValue < T > (reader, type);
             else
                list  =  CreateObject < T > (reader, type);
            reader.Dispose();
            reader.Close();
             return  list;
        }

         private  IList < T >  CreateObject < T > (SqlDataReader reader, Type type)
        {
            IList < T >  list  =   new  List < T > ();
            PropertyInfo[] properties  =  type.GetProperties();
             string  name  =   string .Empty;
             while  (reader.Read())
            {
                T local  =  Activator.CreateInstance < T > ();
                 for  ( int  i  =   0 ; i  <  reader.FieldCount; i ++ )
                {
                    name  =  reader.GetName(i);
                     foreach  (PropertyInfo info  in  properties)
                    {
                         if  (name.Equals(info.Name))
                        {
                            info.SetValue(local, Convert.ChangeType(reader[info.Name], info.PropertyType),  null );
                             break ;
                        }
                    }
                }
                list.Add(local);
            }
             return  list;
        }

         private  IList < T >  CreateValue < T > (SqlDataReader reader, Type type)
        {
            IList < T >  list  =   new  List < T > ();
             while  (reader.Read())
            {
                T local  =  (T)Convert.ChangeType(reader[ 0 ], type,  null );
                list.Add(local);
            }
             return  list;
        }
    }

调用示例：

View Code

  ///   <summary>
        ///  事务示例
        ///   </summary>
         public   void  TestExecuteNonQueryBeginTran()
        {

             try
            {
                SqlHelper.Instance().BeginTransaction();
                SqlHelper.Instance().ExecuteNonQuery(CommandType.Text,  " update  warningTest set pid=0 where id=3 " );
                SqlHelper.Instance().ExecuteNonQuery(CommandType.Text,  " update  warningTest set pid=aaa where id=4 " );
                SqlHelper.Instance().CommitTransaction();
                 int  num  =  SqlHelper.Instance().ExecuteNonQuery(System.Data.CommandType.Text,  " select * from warningTest " );
            }
             catch  { SqlHelper.Instance().RollbackTransaction(); }
        }

         ///   <summary>
         ///  返回实体集合示例
         ///   </summary>
         public   void  TestExecuteReaderList()
        {

            SqlParameter para  =   new  SqlParameter( " @id " ,  1 );
            warningTest warning  =  SqlHelper.Instance().ExecuteReaderObject < warningTest > (CommandType.Text,  " select * from warningTest where id=@id " , para);
            Assert.AreEqual( 1 , warning.id);
        }

         ///   <summary>
         ///  返回值类型集合示例
         ///   </summary>
         public   void  TestExecuteReaderListByInt()
        {
            IList < string >  list  =  SqlHelper.Instance().ExecuteReaderList < string > (CommandType.Text,  " select Logic from warningTest " );
             foreach  ( string  i  in  list)
            {
                Console.WriteLine(i.ToString());
            }
        }

下载： 项目源代码

补充说明：数据库备份文件在Data.test\App_Data文件夹下面