我正在开发一个 winforms c# visual studio 2008 应用程序。该应用程序与 excel 文件对话,我正在使用 Microsoft.Office.Interop.Excel;
来执行此操作。
我想知道如何确保即使出现错误也能释放对象?
这是我的代码:
private void button1_Click(object sender, EventArgs e)
{
string myBigFile="";
OpenFileDialog openFileDialog1 = new OpenFileDialog();
DialogResult result = openFileDialog1.ShowDialog(); // Show the dialog.
if (result == DialogResult.OK) // Test result.
myBigFile=openFileDialog1.FileName;
Excel.Application xlApp;
Excel.Workbook xlWorkBook;
Excel.Worksheet xlWorkSheet;
Excel.Range range;
string str;
int rCnt = 0;
int cCnt = 0;
xlApp = new Excel.ApplicationClass();
xlWorkBook = xlApp.Workbooks.Open(myBigFile, 0, true, 5, "", "", true, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", true, false, 0, true, 1, 0);
xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);
range = xlWorkSheet.UsedRange;
/*
for (rCnt = 1; rCnt <= range.Rows.Count; rCnt++)
{
for (cCnt = 1; cCnt <= range.Columns.Count; cCnt++)
{
str = (string)(range.Cells[rCnt, cCnt] as Excel.Range).Value2;
MessageBox.Show(str);
}
}
*/
xlWorkSheet..EntireRow.Delete(Excel.XLDirection.xlUp)
xlWorkBook.SaveAs(xlWorkBook.Path + @"\XMLCopy.xls", Excel.XlFileFormat.xlXMLSpreadsheet, Type.Missing, Type.Missing,
false, false, Excel.XlSaveAsAccessMode.xlNoChange,
Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);
xlWorkBook.Close(true, null, null);
xlApp.Quit();
releaseObject(xlWorkSheet);
releaseObject(xlWorkBook);
releaseObject(xlApp);
}
private void releaseObject(object obj)
{
try
{
System.Runtime.InteropServices.Marshal.ReleaseComObject(obj);
obj = null;
}
catch (Exception ex)
{
obj = null;
MessageBox.Show("Unable to release the Object " + ex.ToString());
}
finally
{
GC.Collect();
}
}
我如何确保即使在打开工作簿后出现错误,我也能确保处置对象:
Excel.Application xlApp;
Excel.Workbook xlWorkBook;
Excel.Worksheet xlWorkSheet;
Excel.Range range;
换句话说,无论我需要以下几行来运行什么
xlWorkBook.Close(true, null, null);
xlApp.Quit();
releaseObject(xlWorkSheet);
releaseObject(xlWorkBook);
releaseObject(xlApp);
请注意,我也试过这个,导致同样的问题
xlWorkBook.Close(false, System.Reflection.Missing.Value, System.Reflection.Missing.Value);
xlApp.Quit();
Marshal.ReleaseComObject(xlWorkSheet);
Marshal.ReleaseComObject(xlWorkBook);
Marshal.ReleaseComObject(xlApp);
xlWorkSheet = null;
xlWorkBook = null;
xlApp = null;
GC.GetTotalMemory(false);
GC.Collect();
GC.WaitForPendingFinalizers();
GC.Collect();
GC.GetTotalMemory(true);
我也这样做了:
GC.Collect() ;
GC.WaitForPendingFinalizers();
GC.Collect() ;
GC.WaitForPendingFinalizers();
Marshal.FinalReleaseComObject(xlWorkSheet);
xlWorkBook.Close(Type.Missing, Type.Missing, Type.Missing);
Marshal.FinalReleaseComObject(xlWorkBook);
xlApp.Quit();
Marshal.FinalReleaseComObject(xlApp);
在这一点上,我认为不可能从 visual studio 2008 中关闭 excel。它一定是一个错误或什么的,但我已经尝试了排名前 20 位的网站并得到了相同的结果:excel 正在打开两个实例出于某种原因,当我进行垃圾收集等时。(或不)它只关闭一个实例。
当我尝试打开文件时,它说有错误或文件已损坏。
当我转到任务管理器并终止 excel 进程时,文件将正常打开。]
有没有办法用 visual studio 2008 关闭 excel?如果是这样,您能否为我提供指导或解决方案
最佳答案
首先我将展示一个修改过的releaseObject
,然后我将提供一个使用它的模式。
using Marshal = System.Runtime.InteropServices.Marshal;
private void releaseObject(ref object obj) // note ref!
{
// Do not catch an exception from this.
// You may want to remove these guards depending on
// what you think the semantics should be.
if (obj != null && Marshal.IsComObject(obj)) {
Marshal.ReleaseComObject(obj);
}
// Since passed "by ref" this assingment will be useful
// (It was not useful in the original, and neither was the
// GC.Collect.)
obj = null;
}
现在,要使用的模式:
private void button1_Click(object sender, EventArgs e)
{
// Declare. Assign a value to avoid a compiler error.
Excel.Application xlApp = null;
Excel.Workbook xlWorkBook = null;
Excel.Worksheet xlWorkSheet = null;
try {
// Initialize
xlApp = new Excel.ApplicationClass();
xlWorkBook = xlApp.Workbooks.Open(myBigFile, 0, true, 5, "", "", true, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", true, false, 0, true, 1, 0);
// If the cast fails this like could "leak" a COM RCW
// Since this "should never happen" I wouldn't worry about it.
xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);
...
} finally {
// Release all COM RCWs.
// The "releaseObject" will just "do nothing" if null is passed,
// so no need to check to find out which need to be released.
// The "finally" is run in all cases, even if there was an exception
// in the "try".
// Note: passing "by ref" so afterwords "xlWorkSheet" will
// evaluate to null. See "releaseObject".
releaseObject(ref xlWorkSheet);
releaseObject(ref xlWorkBook);
// The Quit is done in the finally because we always
// want to quit. It is no different than releasing RCWs.
if (xlApp != null) {
xlApp.Quit();
}
releaseObject(ref xlApp);
}
}
这种简单的方法可以在大多数情况下进行扩展/嵌套。我使用实现 IDisposable 的自定义包装类来简化此任务。
关于c# - 在 C# 中安全地处理 Excel 互操作对象?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/9962157/