DataAccess通用数据库访问类，简单易用，功能强悍

以下是我编写的DataAccess通用数据库访问类，简单易用，支持：内联式创建多个参数、支持多事务提交、支持参数复用、支持更换数据库类型，希望能帮到大家，若需支持查出来后转换成实体，可以自行扩展datarow转实体类，也可以搭配dapper.net实现更强大的功能。

  /// <summary>  /// 通用数据库访问类，支持多种数据库，无直接依赖某个数据库组件  /// 作者：左文俊  /// 日期：2016-6-3  /// </summary>  public class DataAccess : IDisposable  {    private static DbProviderFactory dbProviderFactory = null;    private static get='_blank'>string connectionString = null;    public static string ConnectionStringName = "default";    private DbConnection dbConnection = null;    private DbTransaction dbTransaction = null;    private bool useTransaction = false;    private bool disposed = false;    private bool committed = false;    private ParameterHelperClass paramHelper = null;    public DataAccess()      : this(ConnectionStringName)    { }    public DataAccess(string cnnStringName)    {      if (!ConnectionStringName.Equals(cnnStringName, StringComparison.OrdinalIgnoreCase) ||        dbProviderFactory == null || connectionString == null)      {        ConnectionStringName = cnnStringName;        var cnnStringSection = ConfigurationManager.ConnectionStrings[cnnStringName];        dbProviderFactory = DbProviderFactories.GetFactory(cnnStringSection.ProviderName);        connectionString = cnnStringSection.ConnectionString;      }      paramHelper = new ParameterHelperClass(this);    }    #region 私有方法    private DbConnection GetDbConnection()    {      if (dbConnection == null)      {        dbConnection = dbProviderFactory.CreateConnection();        dbConnection.ConnectionString = connectionString;      }      if (dbConnection.State == ConnectionState.Closed)      {        dbConnection.Open();      }      if (useTransaction && dbTransaction == null)      {        dbTransaction = dbConnection.BeginTransaction();        committed = false;      }      return dbConnection;    }    private DbCommand BuildDbCommand(string sqlCmdText, CommandType cmdType = CommandType.Text, DbParameter[] parameters = null)    {      var dbCmd = dbProviderFactory.CreateCommand();      var dbConn = GetDbConnection();      dbCmd.Connection = dbConn;      dbCmd.CommandText = sqlCmdText;      dbCmd.CommandType = cmdType;      if (useTransaction)      {        dbCmd.Transaction = dbTransaction;      }      if (parameters != null)      {        dbCmd.Parameters.AddRange(parameters);      }      return dbCmd;    }    private DbCommand BuildDbCommand(string sqlCmdText, CommandType cmdType = CommandType.Text, IDictionary<string, object> paramNameValues = null)    {      List<DbParameter> parameters = new List<DbParameter>();      if (paramNameValues != null)      {        foreach (var item in paramNameValues)        {          parameters.Add(BuildDbParameter(item.Key, item.Value));        }      }      return BuildDbCommand(sqlCmdText, cmdType, parameters.ToArray());    }    private DbCommand BuildDbCommand(string sqlCmdText, CommandType cmdType = CommandType.Text, params object[] paramObjs)    {      if (paramObjs != null)      {        if (paramObjs[0] is IDictionary<string, object>)        {          return BuildDbCommand(sqlCmdText, cmdType, paramObjs[0] as IDictionary<string, object>);        }        else if (paramObjs is DbParameter[])        {          return BuildDbCommand(sqlCmdText, cmdType, paramObjs as DbParameter[]);        }        else        {          List<DbParameter> parameters = new List<DbParameter>();          for (int i = 0; i < paramObjs.Length; i++)          {            parameters.Add(BuildDbParameter("@p" + i.ToString(), paramObjs[0]));          }          return BuildDbCommand(sqlCmdText, cmdType, parameters.ToArray());        }      }      else      {        return BuildDbCommand(sqlCmdText, cmdType, parameters: null);      }    }    private void ClearCommandParameters(DbCommand cmd)    {      bool canClear = true;      if (cmd.Connection != null && cmd.Connection.State != ConnectionState.Open)      {        foreach (DbParameter commandParameter in cmd.Parameters)        {          if (commandParameter.Direction != ParameterDirection.Input)          {            canClear = false;            break;          }        }      }      if (canClear)      {        cmd.Parameters.Clear();      }    }    #endregion    #region 公共方法    public void UseTransaction()    {      useTransaction = true;    }    public void Commit()    {      if (dbTransaction != null && useTransaction)      {        dbTransaction.Commit();        dbTransaction.Dispose();        dbTransaction = null;        committed = true;        useTransaction = false;      }    }    public DbParameter BuildDbParameter(string name, object value)    {      DbParameter parameter = dbProviderFactory.CreateParameter();      parameter.ParameterName = name;      parameter.Value = value;      return parameter;    }    public DbParameter BuildDbParameter(string name, object value, DbType dbType, ParameterDirection direction = ParameterDirection.Input)    {      DbParameter parameter = dbProviderFactory.CreateParameter();      parameter.ParameterName = name;      parameter.Value = value;      parameter.DbType = dbType;      parameter.Direction = direction;      return parameter;    }    public DbDataReader ExecuteReader(string sqlCmdText, CommandType cmdType = CommandType.Text, params object[] paramObjs)    {      var dbCmd = BuildDbCommand(sqlCmdText, cmdType, paramObjs);      var dr = dbCmd.ExecuteReader();      ClearCommandParameters(dbCmd);      return dr;    }    public T ExecuteScalar<T>(string sqlCmdText, CommandType cmdType = CommandType.Text, params object[] paramObjs)    {      T returnValue = default(T);      var dbCmd = BuildDbCommand(sqlCmdText, cmdType, paramObjs);      object result = dbCmd.ExecuteScalar();      try      {        returnValue = (T)Convert.ChangeType(result, typeof(T));      }      catch      { }      ClearCommandParameters(dbCmd);      return returnValue;    }    public DataSet ExecuteDataSet(string sqlCmdText, CommandType cmdType = CommandType.Text, params object[] paramObjs)    {      var dbCmd = BuildDbCommand(sqlCmdText, cmdType, paramObjs);      var dbAdapter = dbProviderFactory.CreateDataAdapter();      dbAdapter.SelectCommand = dbCmd;      DataSet returnDataSet = new DataSet();      dbAdapter.Fill(returnDataSet);      ClearCommandParameters(dbCmd);      return returnDataSet;    }    public DataTable ExecuteDataTable(string sqlCmdText, CommandType cmdType = CommandType.Text, params object[] paramObjs)    {      DataTable returnTable = new DataTable();      DataSet resultDataSet = ExecuteDataSet(sqlCmdText, cmdType, paramObjs);      if (resultDataSet != null && resultDataSet.Tables.Count > 0)      {        returnTable = resultDataSet.Tables[0];      }      return returnTable;    }    public int ExecuteCommand(string sqlCmdText, CommandType cmdType = CommandType.Text, params object[] paramObjs)    {      var dbCmd = BuildDbCommand(sqlCmdText, cmdType, paramObjs);      int execResult = dbCmd.ExecuteNonQuery();      ClearCommandParameters(dbCmd);      return execResult;    }    public void Dispose()    {      Dispose(true);      GC.SuppressFinalize(this);    }    #endregion    private void Dispose(bool disposing)    {      if (!disposed)      {        if (disposing)        {          //释放托管资源        }        if (dbTransaction != null)        {          if (!committed)          {            dbTransaction.Rollback();          }          dbTransaction.Dispose();        }        if (dbConnection != null)        {          if (dbConnection.State != ConnectionState.Closed)          {            dbConnection.Close();          }          dbConnection.Dispose();        }        disposed = true;      }    }    ~DataAccess()    {      Dispose(false);    }    public ParameterHelperClass ParameterHelper    {      get      {        return paramHelper;      }    }    public class ParameterHelperClass    {      private List<DbParameter> parameterList = null;      private DataAccess parent = null;      public ParameterHelperClass(DataAccess da)      {        parent = da;        parameterList = new List<DbParameter>();      }      public ParameterHelperClass AddParameter(string name, object value)      {        parameterList.Add(parent.BuildDbParameter(name, value));        return this;      }      public ParameterHelperClass AddParameter(string name, object value, DbType dbType, ParameterDirection direction = ParameterDirection.Input)      {        parameterList.Add(parent.BuildDbParameter(name, value, dbType, direction));        return this;      }      public ParameterHelperClass AddParametersWithValue(params object[] paramValues)      {        for (int i = 0; i < paramValues.Length; i++)        {          parameterList.Add(parent.BuildDbParameter("@p" + i.ToString(), paramValues[0]));        }        return this;      }      public DbParameter[] ToParameterArray()      {        var paramList = parameterList;        parameterList = new List<DbParameter>();        return paramList.ToArray();      }    }  }

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原标题：DataAccess通用数据库访问类，简单易用，功能强悍

关键词：数据库