上回书说到,最近我在写一个Office PIA的程序。我先是写了一个独立的小工程,完美地实现了对Excel Workbook的各种操作,并且也反复作了测试。然后往我们真实的项目里合并。这里有个伏笔:我们team用的是Visual Studio 2008,而我个人用的是Visual Studio 2010。我没忘记在我的Visual Studio 2010工程里面把.Net Framework的版本设置为3.5。这个地方要跟我们实际的项目保持一致,这一点我还是很注意的。
谁曾想,合并的时候出了问题,编译出现一大堆错误。
比如说这个方法:
/// <summary> /// Creates the excel doc. /// </summary> /// <param name="fileName">the excel doc filename</param> public void CreateWorkbook(string fileName) { try { this.CurrentWorkbook = this.Application.Workbooks.Add(Excel.XlWBATemplate.xlWBATWorksheet); this.LatestWorksheet = this.CurrentWorkbook.Sheets[1] as Excel.Worksheet; this.CurrentWorksheet = this.LatestWorksheet; string fullPath = this.GetActualFullPath(fileName); this.LatestWorksheet.SaveAs( fullPath, this.currentFileFormat, Type.Missing, Type.Missing, Type.Missing, Type.Missing); } catch (Exception ex) { this.Close(); throw ex; } }
Compile error: No overload for method 'SaveAs' takes '6' arguments ......
/// <summary> /// Creates the excel doc. /// </summary> /// <param name="fileName">the excel doc filename</param> public void CreateWorkbook(string fileName) { try { this.CurrentWorkbook = this.Application.Workbooks.Add(Excel.XlWBATemplate.xlWBATWorksheet); this.LatestWorksheet = this.CurrentWorkbook.Sheets[1] as Excel.Worksheet; this.CurrentWorksheet = this.LatestWorksheet; string fullPath = this.GetActualFullPath(fileName); this.LatestWorksheet.SaveAs( fullPath, this.currentFileFormat, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Excel.XlSaveAsAccessMode.xlExclusive, Type.Missing, Type.Missing, Type.Missing); } catch (Exception ex) { this.Close(); throw ex; } }
同样的问题多处出现。比如说Visual Studio 2010下能编译通过的这段代码:
/// <summary> /// Create new worksheet and insert it after current worksheet. /// </summary> /// <param name="worksheetName">name of the new worksheet</param> public void AddWorksheetAfter(object worksheetName) { this.LatestWorksheet = this.CurrentWorkbook.Worksheets.Add(Type.Missing, worksheetName) as Excel.Worksheet; this.Save(); }
Compile error: No overload for method 'Add' takes '2' arguments ......
/// <summary> /// Create new worksheet and insert it after current worksheet. /// </summary> /// <param name="worksheetName">name of the new worksheet</param> public void AddWorksheetAfter(object worksheetName) { this.LatestWorksheet = this.CurrentWorkbook.Worksheets.Add(Type.Missing, worksheetName, Type.Missing, Type.Missing) as Excel.Worksheet; this.Save(); }
这是为什么呢?首先请不要疑神疑鬼,不要惊慌,要相信科学,遇到问题要广泛地借助Google和MSDN这两个好工具。
Visual Studio 2008编译出错的地方,全都是出在Office PIA的Interop COM组件的可选参数之处。在Visual Studio 2010中,尽管我的.Net Framework版本选择的是3.5,但是由于Visual Studio 2010的编辑器本身支持C# 4.0的一些“语法糖”,C# 4.0对于COM组件的互操作性作了增强,支持了可选参数的省略,因此我在编程中省掉了那一大堆Type.Missing。这样,我在Visual Studio 2010下写的代码显得很简洁。当然也正是这些地方造成了在Visual Studio 2008下编译的困扰。
MSDN中相关的链接如下:
问题的查找与解决并不复杂。尽管这是由Visual Studio 2010的新特性给我造成的小麻烦,但是遇到这样的小麻烦,心情还是很愉悦的,我不认为这是什么坏事情。