解决在IIS中调用Microsoft Office Excel组件后进程无法正常退出的问题
有一个项目用到Excel组件产生报表，本以为这个通用功能是个很简单的case，没想到结果却花了不少时间
本人开发环境: Win7 64bit + IIS7.5 + VS2012
最开始碰到的问题是NetworkService无法访问com组件，需要对帐户进行授权，这个相信很多人都碰到过，也很好解决
1.运行：mmc comexp.msc /32，找到我的电脑 -> DCom配置中的Microsoft Excel Application
2.在Microsoft Excel Application上点击右键，选择"属性"
3.点击"标识"标签,选择"交互式用户"
4.点击"安全"标签,在"启动和激活权限"上点击"自定义",然后点击对应的"编辑"按钮,在弹出的"安全性"对话框中填加一个"NETWORK SERVICE"用户(注意要选择本计算机名),并给它赋予"本地启动"和"本地激活"权限.
5.依然是"安全"标签,在"访问权限"上点击"自定义",然后点击"编辑",在弹出的"安全性"对话框中也填加一个"NETWORK SERVICE"用户,然后赋予"本地访问"权限.
之后程序能正常运行了，但这个项目需要并发处理，可能有多个ApplicationClass实例，这时问题就来了
调用_Application.Quit()之后，Excel.exe进程仍然存在，搜索之后，解决方案来了:
[DllImport("User32.dll", CharSet = CharSet.Auto)] public static extern int GetWindowThreadProcessId(IntPtr hwnd, out int proecessId); public static void KillExcel(Excel.Application excel) { var t = new IntPtr(excel.Hwnd); int proecessId = 0; GetWindowThreadProcessId(t, out proecessId); Process.GetProcessById(proecessId).Kill(); }
用VS调试正常工作，在Console应用里也OK，但如果用IIS启动就不行了，断点调用发现GetWindowThreadProcessId取得的processId一直为0。
搜索了一下网站，大概意思是运行在不同的Session级别，Excel是以"交互式用户"启动，即本地Administrator，所以取不到对应的进程Id，
于是又在Microsoft Excel Application的属性->标识中将启动用户这项选中，发现这回Excel进程是以NetworkService启动，测试代码如下:
Application excel = new ApplicationClass { Visible = false, DisplayAlerts = false }; excel.Quit(); KillExcel(excel);
也能正常退出，好像问题已经解决了，OK，来编写业务代码了
Workbook workbook = excel.Workbooks.Add(true);
一调试，马上报异常，继续Google和看微软官方网站，发现Office自动化必须以交互式用户方式来启动，而NetworkService是虚拟的，所以这条路显然走不通。
即使你想到给NetworkService提升权限，也不清楚正常运行Excel倒底要那些权限，搜索后也无果，大部分推荐使用第三方组件，或者建立一个专用的帐户，或者建立一个Service项目来处理Http请求。
这些方式各有各的不足，将建立专用域帐户做一备选方案后，继续寻求解决办法，最先找到的代码是:
Application excel = new ApplicationClass { Visible = false, DisplayAlerts = false }; Workbook workbook = excel.Workbooks.Add(true); Worksheet worksheet = (Worksheet)workbook.ActiveSheet; // do sth excel.Quit(); Marshal.ReleaseComObject(worksheet); workbook.Close(false, null, null); Marshal.ReleaseComObject(workbook); Marshal.ReleaseComObject(excel);
这段代码相信遇到这个问题的人都试过吧，结果还是不行，在IIS下面启动的Excel进程不一定按你的要求及时退出
后来一位高手同事给了个链接 http://support.microsoft.com/kb/317109
测试代码:
Application excel = new ApplicationClass { Visible = false, DisplayAlerts = false }; Workbooks workbooks = excel.Workbooks; Workbook workbook = workbooks.Add(true); Worksheet worksheet = (Worksheet)workbook.ActiveSheet; // do sth excel.Quit(); Marshal.ReleaseComObject(worksheet); workbook.Close(false, null, null); Marshal.ReleaseComObject(workbook); Marshal.ReleaseComObject(workbooks); Marshal.ReleaseComObject(excel);
这段代码测试正常，看到希望了，继续Coding，然后测试。
服务器运行一段时间后，仍然存在大量的Excel进程没有退出，有心的人估计从两段稍有差别的代码看到问题的所在了，问题就在于:
调用com+对象后，必须要及时释放资源，那怕你只是请求了某个属性，只要这个属性是com+资源，也得显示释放资源
代码如下:
public class ExcelApp : IDisposable { private Application _excel; private Workbooks _workbooks; private Workbook _workbook; private Worksheet _worksheet; public ExcelApp() { _excel = new ApplicationClass { Visible = false, DisplayAlerts = false }; _workbooks = _excel.Workbooks; } public int ColCount { get; set; } public int RowCount { get; set; } public string WorksheetName { get { return _worksheet != null ? _worksheet.Name : null; } set { if (_worksheet != null) { _worksheet.Name = value; } } } #region Get Excel Range public Range GetCell(int rowIndex, int cellIndex) { Range cells = null; Range range = null; try { cells = _excel.Cells; range = (Range)cells[1 + rowIndex, 1 + cellIndex]; } finally { Marshal.ReleaseComObject(cells); } return range; } public Range GetColumn(int cellIndex) { Range range = null; Range cells = null; object rangeX = null; object rangeY = null; try { cells = _excel.Cells; rangeX = cells[1, 1 + cellIndex]; rangeY = cells[RowCount, 1 + cellIndex]; range = _worksheet.get_Range(rangeX, rangeY); } finally { Marshal.ReleaseComObject(rangeX); Marshal.ReleaseComObject(rangeY); Marshal.ReleaseComObject(cells); } return range; } public Range GetRange(int xRowIndex, int xCellIndex, int yRowIndex, int yCellIndex) { Range range = null; Range cells = null; object rangeX = null; object rangeY = null; try { cells = _excel.Cells; rangeX = cells[1 + xRowIndex, 1 + xCellIndex]; rangeY = cells[yRowIndex + 1, yCellIndex + 1]; range = _worksheet.get_Range(rangeX, rangeY); } finally { Marshal.ReleaseComObject(rangeX); Marshal.ReleaseComObject(rangeY); Marshal.ReleaseComObject(cells); } return range; } #endregion public void Save(string fullFilePath) { if (string.IsNullOrEmpty(fullFilePath)) { throw new ArgumentNullException("fullFilePath"); } string directory = Path.GetDirectoryName(fullFilePath); if (string.IsNullOrEmpty(directory)) { throw new ArgumentException("fullFilePath is not a valid file path."); } if (!Directory.Exists(directory)) { Directory.CreateDirectory(directory); } _workbook.SaveCopyAs(fullFilePath); } public void Open(string fullFilePath) { _workbook = _workbooks._Open(fullFilePath, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value); _worksheet = (Worksheet)_workbook.ActiveSheet; ColCount = 0; RowCount = 0; } public void AddWorkbook() { _workbook = _workbooks.Add(true); _worksheet = (Worksheet)_workbook.ActiveSheet; ColCount = 0; RowCount = 0; } public void Reset() { Close(); AddWorkbook(); } private void Close() { if (_worksheet != null) { Marshal.ReleaseComObject(_worksheet); } if (_workbook != null) { _workbook.Close(false, null, null); Marshal.ReleaseComObject(_workbook); } _worksheet = null; _workbook = null; } #region IDisposable Members public void Dispose() { try { Close(); if (_workbooks != null) { Marshal.ReleaseComObject(_workbooks); } if (_excel != null) { _excel.Quit(); Marshal.ReleaseComObject(_excel); } } catch (Exception ex) { Console.WriteLine("dispose ExcelApp object failed", ex); } _workbooks = null; _excel = null; } #endregion } public class Disposable { public static Disposable<T> Create<T>(T o) where T : class { return new Disposable<T>(o); } } public class Disposable<T> : IDisposable where T : class { public T Value; internal Disposable(T o) { Value = o; } public void Dispose() { if (Value != null) { Marshal.ReleaseComObject(Value); } } }
调用示例:
View Code
using (var excel = new ExcelApp()) { excel.AddWorkbook(); using (var range = Disposable.Create(excel.GetCell(0, 0))) { using (var font = Disposable.Create(range.Value.Font)) { font.Value.Color = 255; } range.Value.Value = 200; } }
至此在IIS里调用Excel不能退出的问题总算圆满解决了，贴出来和大家分享一下，免得其他人也在这上面浪费时间