DBHelper的两种实现方式
Method 1.
According to the abstract class of ADO.NET,accomplish the core code of ADO.NET,named DBHelper.
Then generate a concrete database ADO.NET object using factory,as the below showing.
public class DBHelper
{
//获取数据库类型
private static string strDbType = CommonUtils.GetConfigValueByKey("dbType").ToUpper();
//将数据库类型转换成枚举类型
public static DatabaseType DbType = DatabaseTypeEnumParse<DatabaseType>(strDbType);
//获取数据库连接字符串
public static string ConnectionString = GetConnectionString("connectionString");
//获取数据库命名参数符号，比如@(SQLSERVER)、:(ORACLE)
public static string DbParmChar = DbFactory.CreateDbParmCharacter();
private static Hashtable parmCache = Hashtable.Synchronized(new Hashtable());
/// <summary>
///通过提供的参数，执行无结果集的数据库操作命令
/// 并返回执行数据库操作所影响的行数。
/// </summary>
/// <param name="connectionString">数据库连接字符串</param>
/// <param name="commandType">执行命令的类型（存储过程或T-SQL，等等）</param>
/// <param name="commandText">存储过程名称或者T-SQL命令行<</param>
/// <param name="commandParameters">执行命令所需的参数数组</param>
/// <returns>返回通过执行命令所影响的行数</returns>
public static int ExecuteNonQuery(string connectionString, CommandType cmdType, string cmdText, params IDbDataParameter[] commandParameters)
{
IDbCommand cmd = DbFactory.CreateDbCommand();
using (IDbConnection conn = DbFactory.CreateDbConnection(connectionString))
{
PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
int val = cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return val;
}
}
/// <summary>
///通过提供的参数，执行无结果集的数据库操作命令
/// 并返回执行数据库操作所影响的行数。
/// </summary>
/// <param name="connectionString">数据库连接字符串</param>
/// <param name="commandType">执行命令的类型（存储过程或T-SQL，等等）</param>
/// <param name="commandText">存储过程名称或者T-SQL命令行<</param>
/// <returns>返回通过执行命令所影响的行数</returns>
public static int ExecuteNonQuery(string connectionString, CommandType cmdType, string cmdText)
{
IDbCommand cmd = DbFactory.CreateDbCommand();
using (IDbConnection conn = DbFactory.CreateDbConnection(connectionString))
{
PrepareCommand(cmd, conn, null, cmdType, cmdText, null);
int val = cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return val;
}
}
/// <summary>
///通过提供的参数，执行无结果集返回的数据库操作命令
///并返回执行数据库操作所影响的行数。
/// </summary>
/// <remarks>
/// e.g.:
/// int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
/// </remarks>
/// <param name="conn">数据库连接对象</param>
/// <param name="commandType">执行命令的类型（存储过程或T-SQL，等等）</param>
/// <param name="commandText">存储过程名称或者T-SQL命令行</param>
/// <param name="commandParameters">执行命令所需的参数数组</param>
/// <returns>返回通过执行命令所影响的行数</returns>
public static int ExecuteNonQuery(IDbConnection connection, CommandType cmdType, string cmdText, params IDbDataParameter[] commandParameters)
{
IDbCommand cmd = DbFactory.CreateDbCommand();
PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
int val = cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return val;
}
/// <summary>
///通过提供的参数，执行无结果集返回的数据库操作命令
///并返回执行数据库操作所影响的行数。
/// </summary>
/// <remarks>
/// e.g.:
/// int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
/// </remarks>
/// <param name="conn">数据库连接对象</param>
/// <param name="commandType">执行命令的类型（存储过程或T-SQL，等等）</param>
/// <param name="commandText">存储过程名称或者T-SQL命令行</param>
/// <returns>返回通过执行命令所影响的行数</returns>
public static int ExecuteNonQuery(IDbConnection connection, CommandType cmdType, string cmdText)
{
IDbCommand cmd = DbFactory.CreateDbCommand();
PrepareCommand(cmd, connection, null, cmdType, cmdText, null);
int val = cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return val;
}
/// <summary>
///通过提供的参数，执行无结果集返回的数据库操作命令
///并返回执行数据库操作所影响的行数。
/// </summary>
/// <remarks>
/// e.g.:
/// int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
/// </remarks>
/// <param name="trans">sql事务对象</param>
/// <param name="commandType">执行命令的类型（存储过程或T-SQL，等等）</param>
/// <param name="commandText">存储过程名称或者T-SQL命令行<</param>
/// <param name="commandParameters">执行命令所需的参数数组</param>
/// <returns>返回通过执行命令所影响的行数</returns>
public static int ExecuteNonQuery(IDbTransaction trans, CommandType cmdType, string cmdText, params IDbDataParameter[] commandParameters)
{
IDbConnection conn = null;
if (trans == null)
{
conn = DbFactory.CreateDbConnection(ConnectionString);
}
else
{
conn = trans.Connection;
}
IDbCommand cmd = DbFactory.CreateDbCommand();
PrepareCommand(cmd, conn, trans, cmdType, cmdText, commandParameters);
int val = cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return val;
}
/// <summary>
///通过提供的参数，执行无结果集返回的数据库操作命令
///并返回执行数据库操作所影响的行数。
/// </summary>
/// <remarks>
/// e.g.:
/// int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
/// </remarks>
/// <param name="trans">sql事务对象</param>
/// <param name="commandType">执行命令的类型（存储过程或T-SQL，等等）</param>
/// <param name="commandText">存储过程名称或者T-SQL命令行<</param>
/// <returns>返回通过执行命令所影响的行数</returns>
public static int ExecuteNonQuery(IDbTransaction trans, CommandType cmdType, string cmdText)
{
IDbCommand cmd = DbFactory.CreateDbCommand();
PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, null);
int val = cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return val;
}
/// <summary>
/// 使用提供的参数，执行有结果集返回的数据库操作命令
/// 并返回SqlDataReader对象
/// </summary>
/// <remarks>
/// e.g.:
/// SqlDataReader r = ExecuteReader(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
/// </remarks>
/// <param name="connectionString">数据库连接字符串</param>
/// <param name="commandType">执行命令的类型（存储过程或T-SQL，等等）</param>
/// <param name="commandText">存储过程名称或者T-SQL命令行<</param>
/// <param name="commandParameters">执行命令所需的参数数组</param>
/// <returns>返回SqlDataReader对象</returns>
public static IDataReader ExecuteReader(string connectionString, CommandType cmdType, string cmdText, params IDbDataParameter[] commandParameters)
{
IDbCommand cmd = DbFactory.CreateDbCommand();
IDbConnection conn = DbFactory.CreateDbConnection(connectionString);
//我们在这里使用一个 try/catch,因为如果PrepareCommand方法抛出一个异常，我们想在捕获代码里面关闭
//connection连接对象，因为异常发生datareader将不会存在，所以commandBehaviour.CloseConnection
//将不会执行。
try
{
PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
IDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
cmd.Parameters.Clear();
return rdr;
}
catch
{
conn.Close();
throw;
}
}
/// <summary>
///使用提供的参数，执行有结果集返回的数据库操作命令
/// 并返回SqlDataReader对象
/// </summary>
/// <param name="connectionString">数据库连接字符串</param>
/// <param name="commandType">执行命令的类型（存储过程或T-SQL，等等）</param>
/// <param name="commandText">存储过程名称或者T-SQL命令行<</param>
/// <returns>返回SqlDataReader对象</returns>
public static IDataReader ExecuteReader(string connectionString, CommandType cmdType, string cmdText)
{
IDbCommand cmd = DbFactory.CreateDbCommand();
IDbConnection conn = DbFactory.CreateDbConnection(connectionString);
//我们在这里使用一个 try/catch,因为如果PrepareCommand方法抛出一个异常，我们想在捕获代码里面关闭
//connection连接对象，因为异常发生datareader将不会存在，所以commandBehaviour.CloseConnection
//将不会执行。
try
{
PrepareCommand(cmd, conn, null, cmdType, cmdText, null);
IDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
cmd.Parameters.Clear();
return rdr;
}
catch
{
conn.Close();
throw;
}
}
/// <summary>
/// 查询数据填充到数据集DataSet中
/// </summary>
/// <param name="connectionString">数据库连接字符串</param>
/// <param name="cmdType">执行命令的类型（存储过程或T-SQL，等等）</param>
/// <param name="cmdText">命令文本</param>
/// <param name="commandParameters">参数数组</param>
/// <returns>数据集DataSet对象</returns>
public static DataSet dataSet(string connectionString, CommandType cmdType, string cmdText, params IDbDataParameter[] commandParameters)
{
DataSet ds = new DataSet();
IDbCommand cmd = DbFactory.CreateDbCommand();
IDbConnection conn = DbFactory.CreateDbConnection(connectionString);
try
{
PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
IDbDataAdapter sda = DbFactory.CreateDataAdapter(cmd);
sda.Fill(ds);
return ds;
}
catch
{
conn.Close();
throw;
}
finally
{
conn.Close();
cmd.Dispose();
}
}
/// <summary>
/// 查询数据填充到数据集DataSet中
/// </summary>
/// <param name="connectionString">数据库连接字符串</param>
/// <param name="cmdType">执行命令的类型（存储过程或T-SQL，等等）</param>
/// <param name="cmdText">命令文本</param>
/// <returns>数据集DataSet对象</returns>
public static DataSet dataSet(string connectionString, CommandType cmdType, string cmdText)
{
DataSet ds = new DataSet();
IDbCommand cmd = DbFactory.CreateDbCommand();
IDbConnection conn = DbFactory.CreateDbConnection(connectionString);
try
{
PrepareCommand(cmd, conn, null, cmdType, cmdText, null);
IDbDataAdapter sda = DbFactory.CreateDataAdapter(cmd);
sda.Fill(ds);
return ds;
}
catch
{
conn.Close();
throw;
}
finally
{
conn.Close();
cmd.Dispose();
}
}
/// <summary>
/// 依靠数据库连接字符串connectionString,
/// 使用所提供参数，执行返回首行首列命令
/// </summary>
/// <remarks>
/// e.g.:
/// Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
/// </remarks>
/// <param name="connectionString">数据库连接字符串</param>
/// <param name="commandType">执行命令的类型（存储过程或T-SQL，等等）</param>
/// <param name="commandText">存储过程名称或者T-SQL命令行</param>
/// <param name="commandParameters">执行命令所需的参数数组</param>
/// <returns>返回一个对象，使用Convert.To{Type}将该对象转换成想要的数据类型。</returns>
public static object ExecuteScalar(string connectionString, CommandType cmdType, string cmdText, params IDbDataParameter[] commandParameters)
{
IDbCommand cmd = DbFactory.CreateDbCommand();
using (IDbConnection connection = DbFactory.CreateDbConnection(connectionString))
{
PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
object val = cmd.ExecuteScalar();
cmd.Parameters.Clear();
return val;
}
}
/// <summary>
/// 依靠数据库连接字符串connectionString,
/// 使用所提供参数，执行返回首行首列命令
/// </summary>
/// <remarks>
/// e.g.:
/// Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
/// </remarks>
/// <param name="connectionString">数据库连接字符串</param>
/// <param name="commandType">执行命令的类型（存储过程或T-SQL，等等）</param>
/// <param name="commandText">存储过程名称或者T-SQL命令行</param>
/// <returns>返回一个对象，使用Convert.To{Type}将该对象转换成想要的数据类型。</returns>
public static object ExecuteScalar(string connectionString, CommandType cmdType, string cmdText)
{
IDbCommand cmd = DbFactory.CreateDbCommand();
using (IDbConnection connection = DbFactory.CreateDbConnection(connectionString))
{
PrepareCommand(cmd, connection, null, cmdType, cmdText, null);
object val = cmd.ExecuteScalar();
cmd.Parameters.Clear();
return val;
}
}
/// <summary>
///依靠数据库连接字符串connectionString,
/// 使用所提供参数，执行返回首行首列命令
/// </summary>
/// <remarks>
/// e.g.:
/// Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
/// </remarks>
/// <param name="conn">数据库连接对象</param>
/// <param name="commandType">执行命令的类型（存储过程或T-SQL，等等）</param>
/// <param name="commandText">存储过程名称或者T-SQL命令行</param>
/// <param name="commandParameters">执行命令所需的参数数组</param>
/// <returns>返回一个对象，使用Convert.To{Type}将该对象转换成想要的数据类型。</returns>
public static object ExecuteScalar(IDbConnection connection, CommandType cmdType, string cmdText, params IDbDataParameter[] commandParameters)
{
IDbCommand cmd = DbFactory.CreateDbCommand();
PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
object val = cmd.ExecuteScalar();
cmd.Parameters.Clear();
return val;
}
/// <summary>
///依靠数据库连接字符串connectionString,
/// 使用所提供参数，执行返回首行首列命令
/// </summary>
/// <remarks>
/// e.g.:
/// Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
/// </remarks>
/// <param name="conn">数据库连接对象</param>
/// <param name="commandType">执行命令的类型（存储过程或T-SQL，等等）</param>
/// <param name="commandText">存储过程名称或者T-SQL命令行</param>
/// <param name="commandParameters">执行命令所需的参数数组</param>
/// <returns>返回一个对象，使用Convert.To{Type}将该对象转换成想要的数据类型。</returns>
public static object ExecuteScalar(IDbConnection connection, CommandType cmdType, string cmdText)
{
IDbCommand cmd = DbFactory.CreateDbCommand();
PrepareCommand(cmd, connection, null, cmdType, cmdText, null);
object val = cmd.ExecuteScalar();
cmd.Parameters.Clear();
return val;
}
/// <summary>
/// add parameter array to the cache
/// </summary>
/// <param name="cacheKey">Key to the parameter cache</param>
/// <param name="cmdParms">an array of SqlParamters to be cached</param>
public static void CacheParameters(string cacheKey, params IDbDataParameter[] commandParameters)
{
parmCache[cacheKey] = commandParameters;
}
/// <summary>
/// 查询缓存参数
/// </summary>
/// <param name="cacheKey">使用缓存名称查找值</param>
/// <returns>缓存参数数组</returns>
public static IDbDataParameter[] GetCachedParameters(string cacheKey)
{
IDbDataParameter[] cachedParms = (IDbDataParameter[])parmCache[cacheKey];
if (cachedParms == null)
return null;
IDbDataParameter[] clonedParms = new IDbDataParameter[cachedParms.Length];
for (int i = 0, j = cachedParms.Length; i < j; i++)
clonedParms[i] = (IDbDataParameter)((ICloneable)cachedParms[i]).Clone();
return clonedParms;
}
/// <summary>
/// 为即将执行准备一个命令
/// </summary>
/// <param name="cmd">SqlCommand对象</param>
/// <param name="conn">SqlConnection对象</param>
/// <param name="trans">IDbTransaction对象</param>
/// <param name="cmdType">执行命令的类型（存储过程或T-SQL，等等）</param>
/// <param name="cmdText">存储过程名称或者T-SQL命令行, e.g. Select * from Products</param>
/// <param name="cmdParms">SqlParameters to use in the command</param>
private static void PrepareCommand(IDbCommand cmd, IDbConnection conn, IDbTransaction trans, CommandType cmdType, string cmdText, IDbDataParameter[] cmdParms)
{
if (conn.State != ConnectionState.Open)
conn.Open();
cmd.Connection = conn;
cmd.CommandText = cmdText;
if (trans != null)
cmd.Transaction = trans;
cmd.CommandType = cmdType;
if (cmdParms != null)
{
foreach (IDbDataParameter parm in cmdParms)
cmd.Parameters.Add(parm);
}
}
/// <summary>
/// 根据传入的Key获取配置文件中
/// 相应Key的数据库连接字符串
/// </summary>
/// <param name="Key"></param>
/// <returns></returns>
public static string GetConnectionString(string Key)
{
try
{
return CommonUtils.GetConfigValueByKey(Key);
}
catch
{
throw new Exception("web.config文件appSettings中数据库连接字符串未配置或配置错误，必须为Key=\"connectionString\"");
}
}
/// <summary>
/// 用于数据库类型的字符串枚举转换
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="value"></param>
/// <returns></returns>
public static T DatabaseTypeEnumParse<T>(string value)
{
try
{
return CommonUtils.EnumParse<T>(value);
}
catch
{
throw new Exception("数据库类型\"" + value + "\"错误，请检查！");
}
}
}
View Code
public class DbFactory
{
/// <summary>
/// 根据配置文件中所配置的数据库类型
/// 来获取命令参数中的参数符号oracle为":",sqlserver为"@"
/// </summary>
/// <returns></returns>
public static string CreateDbParmCharacter()
{
string character = string.Empty;
switch (DBHelper.DbType)
{
case DatabaseType.SQLSERVER:
character = "@";
break;
case DatabaseType.ORACLE:
character = ":";
break;
case DatabaseType.ACCESS:
character = "@";
break;
default:
throw new Exception("数据库类型目前不支持！");
}
return character;
}
/// <summary>
/// 根据配置文件中所配置的数据库类型和传入的
/// 数据库链接字符串来创建相应数据库连接对象
/// </summary>
/// <param name="connectionString"></param>
/// <returns></returns>
public static IDbConnection CreateDbConnection(string connectionString)
{
IDbConnection conn = null;
switch (DBHelper.DbType)
{
case DatabaseType.SQLSERVER:
conn = new SqlConnection(connectionString);
break;
case DatabaseType.ORACLE:
conn = new OracleConnection(connectionString);
break;
case DatabaseType.ACCESS:
conn = new OleDbConnection(connectionString);
break;
default:
throw new Exception("数据库类型目前不支持！");
}
return conn;
}
/// <summary>
/// 根据配置文件中所配置的数据库类型
/// 来创建相应数据库命令对象
/// </summary>
/// <returns></returns>
public static IDbCommand CreateDbCommand()
{
IDbCommand cmd = null;
switch (DBHelper.DbType)
{
case DatabaseType.SQLSERVER:
cmd = new SqlCommand();
break;
case DatabaseType.ORACLE:
cmd = new OracleCommand();
break;
case DatabaseType.ACCESS:
cmd = new OleDbCommand();
break;
default:
throw new Exception("数据库类型目前不支持！");
}
return cmd;
}
/// <summary>
/// 根据配置文件中所配置的数据库类型
/// 来创建相应数据库适配器对象
/// </summary>
/// <returns></returns>
public static IDbDataAdapter CreateDataAdapter()
{
IDbDataAdapter adapter = null;
switch (DBHelper.DbType)
{
case DatabaseType.SQLSERVER:
adapter = new SqlDataAdapter();
break;
case DatabaseType.ORACLE:
adapter = new OracleDataAdapter();
break;
case DatabaseType.ACCESS:
adapter = new OleDbDataAdapter();
break;
default:
throw new Exception("数据库类型目前不支持！");
}
return adapter;
}
/// <summary>
/// 根据配置文件中所配置的数据库类型
/// 和传入的命令对象来创建相应数据库适配器对象
/// </summary>
/// <returns></returns>
public static IDbDataAdapter CreateDataAdapter(IDbCommand cmd)
{
IDbDataAdapter adapter = null;
switch (DBHelper.DbType)
{
case DatabaseType.SQLSERVER:
adapter = new SqlDataAdapter((SqlCommand)cmd);
break;
case DatabaseType.ORACLE:
adapter = new OracleDataAdapter((OracleCommand)cmd);
break;
case DatabaseType.ACCESS:
adapter = new OleDbDataAdapter((OleDbCommand)cmd);
break;
default: throw new Exception("数据库类型目前不支持！");
}
return adapter;
}
/// <summary>
/// 根据配置文件中所配置的数据库类型
/// 来创建相应数据库的参数对象
/// </summary>
/// <returns></returns>
public static IDbDataParameter CreateDbParameter()
{
IDbDataParameter param = null;
switch (DBHelper.DbType)
{
case DatabaseType.SQLSERVER:
param = new SqlParameter();
break;
case DatabaseType.ORACLE:
param = new OracleParameter();
break;
case DatabaseType.ACCESS:
param = new OleDbParameter();
break;
default:
throw new Exception("数据库类型目前不支持！");
}
return param;
}
/// <summary>
/// 根据配置文件中所配置的数据库类型
/// 和传入的参数来创建相应数据库的参数数组对象
/// </summary>
/// <returns></returns>
public static IDbDataParameter[] CreateDbParameters(int size)
{
int i = 0;
IDbDataParameter[] param = null;
switch (DBHelper.DbType)
{
case DatabaseType.SQLSERVER:
param = new SqlParameter[size];
while (i < size) { param[i] = new SqlParameter(); i++; }
break;
case DatabaseType.ORACLE:
param = new OracleParameter[size];
while (i < size) { param[i] = new OracleParameter(); i++; }
break;
case DatabaseType.ACCESS:
param = new OleDbParameter[size];
while (i < size) { param[i] = new OleDbParameter(); i++; }
break;
default:
throw new Exception("数据库类型目前不支持！");
}
return param;
}
/// <summary>
/// 根据配置文件中所配置的数据库类型
/// 来创建相应数据库的事物对象
/// </summary>
/// <returns></returns>
public static IDbTransaction CreateDbTransaction()
{
IDbConnection conn = CreateDbConnection(DBHelper.ConnectionString);
if (conn.State == ConnectionState.Closed)
{
conn.Open();
}
return conn.BeginTransaction();
}
}
/// <summary>
/// 数据库类型枚举，需要扩展类型可在此添加
/// </summary>
public enum DatabaseType
{
SQLSERVER,
ORACLE,
ACCESS,
MYSQL
}
Method 2.
First of all,create a abstract ADO.NET Helper,with the function the same as the above-mentioned DBHelper.But it is abstract with the abstract method,for example, protected abstract IDbConnection CreateDbConnection();protected abstract IDbCommand CreateDbCommand(string commandText, IDbConnection con);protected abstract IDbDataAdapter CreateDbDataAdapter(IDbCommand cmd);
Then create the concrete some DBHelper,for instance,SQLDBHelper.The results are as follows.
public class SQLDBHelper: AbstractDBHelper
{
internal override IDbConnection CreateDbConnection()
{
return new SqlConnection(_connectionString);
}
protected override IDbCommand CreateDbCommand(string commandText, IDbConnection con)
{
return new SqlCommand(commandText, (SqlConnection)con);
}
.........................
}
