异步读取 Excel 个工作表

Question

我正在尝试异步读取给定工作簿的所有 Excel 作品sheet，但不知何故它没有发生。这个想法是对每个 Excel sheet 中的前 123 个单元格求和并在最后打印它。代码编译运行s 没有错误，但它没有读取所有工作 sheets，它只是跳过那部分，因为 async.

namespace SyncAndAsync
{
    using System;
    using System.Collections.Generic;
    using System.Threading.Tasks;
    using Excel = Microsoft.Office.Interop.Excel;

    class Startup
    {
        static void Main()
        {
            string filePath = @"C:\Users\Desktop\Sample.xlsx";
            Excel.Application excel = new Excel.Application();
            excel.Visible = true;
            excel.EnableAnimations = false;
            Excel.Workbook wkb = Open(excel, filePath);

            var calculation = CalculateAllWorksheetsAsync(wkb);

            //foreach (var item in calculation)
            //{
            //    Console.WriteLine(item);
            //}

            excel.EnableAnimations = true;
            wkb.Close(true);
            excel.Quit();
        }

        static async Task<List<Information>> CalculateAllWorksheetsAsync(Excel.Workbook wkb)
        {

            List<Task<Information>> tasks = new List<Task<Information>>();

            foreach (Excel.Worksheet wks in wkb.Worksheets)
            {
                Task.Run(() => CalculateSingleWorksheetAsync(wks));
            }

            var results = await Task.WhenAll(tasks);
            return new List<Information>(results);
        }

        static async Task<Information> CalculateSingleWorksheetAsync(Excel.Worksheet wks)
        {
            Information output = new Information();
            int result = 0;
            await Task.Run(() =>
            {
                for (int i = 1; i <= 123; i++)
                {
                    result += (int)(wks.Cells[i, 1].Value);
                }
            });

            output.WorksheetName = wks.Name;
            output.WorksheetSum = result;
            Console.WriteLine($"{wks.Name} - {result}");
            return output;
        }

        static Excel.Workbook Open(Excel.Application excelInstance,
                                            string fileName, bool readOnly = false,
                                            bool editable = true, bool updateLinks = true)
        {
            Excel.Workbook book = excelInstance.Workbooks.Open(
                fileName, updateLinks, readOnly,
                Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing,
                Type.Missing, editable, Type.Missing, Type.Missing, Type.Missing,
                Type.Missing, Type.Missing);
            return book;
        }
    }
}

添加了Informationclass来使用任务，可能可以跳过：

namespace SyncAndAsync
{
    class Information
    {
        public string WorksheetName { get; set; } = "";
        public int WorksheetSum { get; set; } = 0;
    }
}

依赖关系：

应添加引用Microsoft.Office.Interop.Excel；
将 string filePath = @"C:\Users\Desktop\Sample.xlsx"; 更改为相关内容并确保在 Excel 文件中每个 sheet 的第一列中都有一些数字以获得结果；

问题 - 如何实现异步运行并显示所有工作sheet的总和?

Answer 1

有几个问题。首先，任务列表永远不会被填充，因此 WhenAll 调用不会执行任何操作。其次，主函数从不等待CalculateAllWorksheetsAsync的结果。我对您的代码做了一些修改，见下文：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Excel = Microsoft.Office.Interop.Excel;

namespace ExcelTest {
    public class Information {
        public Information(string name, int sum) {
            Name = name;
            Sum = sum;
        }

        public string Name { get; set; }
        public int Sum { get; set; }
    }

    class Program {
        static void Main(){
            MainAsync().GetAwaiter().GetResult();
        }

        private static async Task MainAsync() {
            const string filePath = @"D:\file.xlsx";
            var excel = new Excel.Application {Visible = true, EnableAnimations = false};
            var wkb = Open(excel, filePath);

            var calculation = await CalculateAllWorksheetsAsync(wkb);

            foreach (var item in calculation) {
                Console.WriteLine($"{item.Name} - {item.Sum}");
            }

            excel.EnableAnimations = true;
            wkb.Close(true);
            excel.Quit();
            Console.Read();
        }

        private static async Task<List<Information>> CalculateAllWorksheetsAsync(Excel.Workbook wkb) {
            var tasks = wkb.Worksheets.Cast<Excel.Worksheet>().Select(CalculateSingleWorksheetAsync);
            var results = await Task.WhenAll(tasks);
            return results.ToList();
        }

        private static async Task<Information> CalculateSingleWorksheetAsync(Excel.Worksheet wks) {
            int result = await Task.Run(() =>
                Enumerable.Range(1, 123).Sum(index => (int) (wks.Cells[index, 1].Value2)));

            Console.WriteLine($"{wks.Name} - {result}");
            return new Information(wks.Name, result);
        }

        private static Excel.Workbook Open(Excel.Application excelInstance,
            string fileName, bool readOnly = false,
            bool editable = true, bool updateLinks = true) {
            return excelInstance.Workbooks.Open(
                fileName, updateLinks, readOnly,
                Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing,
                Type.Missing, editable, Type.Missing, Type.Missing, Type.Missing,
                Type.Missing, Type.Missing);
        }
    }
}

示例输出：

异步读取 Excel 个工作表

Read Excel Worksheets Asynchronously

c#

excel

office-interop

com-interop

excel-interop