EXCEL application.quit 不关闭进程问题解决

直接上源码

        public bool Format(string filePath, string outputFile)
        {
        	var excelApplication = new Microsoft.Office.Interop.Excel.Application();
            Workbook workbook = null;
            XlFixedFormatType targetType = XlFixedFormatType.xlTypePDF; //PDF格式
            try
            {

                workbook = excelApplication.Workbooks.Open(filePath);
                if (!File.Exists(outputFile)) //存在PDF，不需要继续转换
                {
                    workbook.ExportAsFixedFormat(targetType, outputFile);
                }
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
                return false;
            }
            finally
            {
                NAR(targetType);
                workbook?.Close();
                NAR(workbook);
                excelApplication.Quit();
                NAR(excelApplication);
                GC.Collect();
            }
            return true;
        }
        
        /// 

        /// 释放资源
        /// 
        /// 
        private void NAR(object o)
        {
            try
            {
                Console.WriteLine(o);
               Console.WriteLine(System.Runtime.InteropServices.Marshal.FinalReleaseComObject(o));
            }
            catch { }
            finally
            {
                o = null;
            }
        }

这个版本看起来没问题，但是我实际测试，无论怎么搞，excel进程依然存在。
最终解决方案

 var workbooks = excelApplication.Workbooks;
 workbook = workbooks.Open(filePath);
 
 NAR(targetType);
 workbook?.Close();
 NAR(workbook);
 workbooks?.Close();
 NAR(workbooks);
 excelApplication.Quit();
 NAR(excelApplication);
 GC.Collect();