public class DisposeTest : IDisposable
{
    //實(shí)現(xiàn)IDisposable接口方法
    public void Dispose()
    {
            
    }
}

    public class DisposeTest : IDisposable
    {

        #region Dispose經(jīng)典實(shí)現(xiàn)方式


        //實(shí)現(xiàn)IDisposable接口方法
        public void Dispose()
        {
            Dispose(true);//調(diào)用處理方法
            GC.SuppressFinalize(this);//讓GC忽略
        }

        //資源
        private readonly IntPtr unmanagedResource;//非托管內(nèi)存
        private readonly SafeHandle managedResource;//托管資源 


        //構(gòu)造方法初始化資源
        public DisposeTest()
        {
            unmanagedResource = Marshal.AllocHGlobal(sizeof(int));//分配非托管內(nèi)存
            managedResource = new SafeFileHandle(new IntPtr(), true);//創(chuàng)建托管資源
        }
		//根據(jù)不同資源進(jìn)行處理
        protected virtual void Dispose(bool isManualDisposing)
        {
            ReleaseUnmanagedResourse(unmanagedResource);//處理非托管資源
            if (isManualDisposing)
            {
                ReleaseManagedResources(managedResource);//處理托管資源 
            }
        }
     
        private void ReleaseUnmanagedResourse(IntPtr intPtr)
        {
            Marshal.FreeHGlobal(intPtr); //釋放非托管內(nèi)存
        }

        private void ReleaseManagedResources(SafeHandle safeHandle)
        {
            if (safeHandle != null)
            {
                safeHandle.Dispose(); //釋放托管資源
            }
        }
      
        //析構(gòu)函數(shù)處理托管資源
        ~DisposeTest()
        {
            Dispose(false);
        }
        #endregion
    }

SqlConnection conn3 = new SqlConnection();
try
{
    conn3.Open();
}
catch (Exception)
{
    throw;
}
finally
{
    conn3.Close();//關(guān)閉對象
}

using (SqlConnection cnn = new SqlConnection())
{
    //此處使用，使用完后系統(tǒng)會(huì)自動(dòng)釋放 
}

SqlConnection cnn2 = new SqlConnection();
try
{            
    //這里寫要執(zhí)行的代碼 
}
finally
{
    cnn2.Dispose();
}