Excel在.Net 环境下Web方式下驻留内存问题的解决

这段时间在VS 2003 的WebForm 方式下对Excel 进行操作，遇到一个最为头疼的问题就是对Excel操作完毕后Excel不能够正常关闭，系统退出后，Excel总是驻留在内存中。但是这段代码放到WinForm的程序中又没有问题。在网上进行了查找也没有找到有效可行的办法。经过无数次的尝试，终于解决如下：
原来书写如下：
private Excel.Application m_app;
private Excel.Workbook m_workbook;
this.m_app = new Excel.ApplicationClass();
this.m_app.DisplayAlerts = false;
this.m_workbook = this.m_app.Workbooks.Open(sFilePath, Missing.Value,
Missing.Value, Missing.Value, Missing.Value,
Missing.Value, Missing.Value, Missing.Value,
Missing.Value, Missing.Value, Missing.Value,
Missing.Value, Missing.Value, Missing.Value,
Missing.Value );
修改后如下：
private Excel.Application m_app;
private Excel.Workbooks m_workbooks;
private Excel.Workbook m_workbook;
this.m_app = new Excel.ApplicationClass();
this.m_app.DisplayAlerts = false;
m_workbooks = this.m_app.Workbooks;
this.m_workbook = this.m_workbooks.Open(sFilePath, Missing.Value,
Missing.Value, Missing.Value, Missing.Value,
Missing.Value, Missing.Value, Missing.Value,
Missing.Value, Missing.Value, Missing.Value,
Missing.Value, Missing.Value, Missing.Value,
Missing.Value );

同样对Sheet的操作如下
修改前如下：
Excel._Worksheet worksheet1 = null;
worksheet1 = (Excel._Worksheet) this.m_workbook.Worksheets.get_Item(sSheetName);
修改后如下：
Excel.Sheets sheets = null ;
Excel._Worksheet worksheet1 = null;
sheets = this.m_workbook.Worksheets;
worksheet1 = (Excel._Worksheet) sheets.get_Item(sSheetName);
发现区别了么？原来Workbooks，Worksheets这两个类没有被实例化就直接使用了，造成该类不能够被回收。最终造成Excel在内存的驻留。
最终以如下方式释放。
private void ReleaseAllRef(Object obj)
{
try
{
if (obj != null )
{
while (Marshal.ReleaseComObject(obj) > 1);
}
}
finally
{
obj = null;
}
}
private void Release()
{
if (m_app != null )
{
m_app.Quit() ;
}
ReleaseAllRef(m_workbook) ;
m_workbook = null ;
ReleaseAllRef(m_workbooks) ;
m_workbooks = null ;
ReleaseAllRef(m_app) ;
m_app = null ;
System.GC.Collect() ;
}