以前设计过ftp/sftp自动下载软件 ，用到了职责链模式，虽然工作没有问题，设计得很粗糙，最近发现工作流workflowcore，很是好用，可以当职责链模式用。

设计一个搜索硬盘上文件的小程序 ，玩一玩这个工作流，创建一个console项目，先nuget“Microsoft.Extensions.Logging”和“WorkflowCore”这二个包，创建Models文件夹，创建SearchFile模型。

namespace WorkflowTest2.Models
{
    internal class SearchFile
    {
        public string? FullName { get; set; }
        public bool IsDirectory { get; set; }
    }
}

再创建SearchFiles模型。

namespace WorkflowTest2.Models
{
    internal class SearchFiles
    {
        public string? SearchFolder { get; set; }

        public string? FolderContains { get; set; } = "";

        public List<SearchFile>? Files { get; set; }
    }
}

SearchFolder用于指定要搜索的文件夹，FolderContains用于指定要包含的文件夹字符串，Files用于装入搜索文件。

再创建Workflow文件夹，先创建Search_StepBody，Workflow有个很重要的概念：“步骤主体”，每个“步骤主体”都是一个黑盒，完成某一个功能，然后把它们组装起来。我设计的这个类，就要继承自StepBody。

using WorkflowCore.Interface;
using WorkflowCore.Models;
using WorkflowTest2.Models;

namespace WorkflowTest2.Workflow
{
    internal class Search_StepBody : StepBody
    {
        public string? SearchFolder { get; set; }
        public List<SearchFile>? SearchFiles { get; set; }
        public override ExecutionResult Run(IStepExecutionContext context)
        {
            if (SearchFolder is not null)
            {
                DirectoryInfo dir = new DirectoryInfo(SearchFolder);
                if (dir.Exists)
                {
                    SearchFiles = new List<SearchFile>();
                    //搜索文件夹
                    var query = dir.EnumerateDirectories().Where(d =>
                    {
                        return !((d.Attributes & FileAttributes.Hidden) == FileAttributes.Hidden);
                    });

                    foreach (var dirinfo in query)
                    {
                        SearchFiles.Add(new SearchFile { FullName = dirinfo.FullName, IsDirectory = true });
                    }
                    //搜索文件
                    var filesQuery = dir.EnumerateFiles().Where(f =>
                    {
                        return !((f.Attributes & FileAttributes.Hidden) == FileAttributes.Hidden);
                    });

                    foreach(var file in filesQuery)
                    {
                        SearchFiles.Add(new SearchFile { FullName = file.FullName, IsDirectory = false });
                    }
                }
            }
            return ExecutionResult.Next();
        }
    }
}

再设计一个stepbody，FolderContains_StepBody，以便更好的玩一玩。

using WorkflowCore.Interface;
using WorkflowCore.Models;
using WorkflowTest2.Models;

namespace WorkflowTest2.Workflow
{
    internal class FolderContains_StepBody : StepBody
    {
        public string? FolderContains { get; set; }

        public List<SearchFile>? InputFiles { get; set; }

        public List<SearchFile>? OutputFiles { get; set; }
        public override ExecutionResult Run(IStepExecutionContext context)
        {
            OutputFiles = new List<SearchFile>();
            //如果foldercontains字符串包含|，则分割成数组。
            if (FolderContains.Contains("|"))
            {
                string[] folders = FolderContains.Split('|');
                foreach (string folder in folders)
                {
                    foreach (var file in InputFiles)
                    {
                        if (file.IsDirectory && file.FullName.ToLower().Contains(folder))
                        {
                            OutputFiles.Add(file);
                        }
                    }
                }
            }
            else
            {
                if (String.IsNullOrWhiteSpace(FolderContains))
                {
                    OutputFiles = InputFiles;
                }
                else
                {
                    foreach (var file in InputFiles)
                    {
                        if (file.IsDirectory)
                        {
                            if(file.FullName.ToLower().Contains(FolderContains))
                            {
                                OutputFiles.Add(file);
                            }                            
                        }
                    }
                }
            }
            //文件夹处理完毕，添加文件
            foreach (var file in InputFiles)
            {
                if (!file.IsDirectory)
                {
                    var matchedFile = OutputFiles.Where(f => f.FullName == file.FullName).FirstOrDefault();

                    if (matchedFile is null)
                    {
                        OutputFiles.Add(file);
                    }
                }
            }
            //去重
            OutputFiles = OutputFiles.Distinct().ToList();
            
            return ExecutionResult.Next();
        }
    }
}

再设计SearchFilesWorkflow工作流，要引用IWorkflow<SearchFiles>，SearchFiles是我们设计要注入进去的数据。

using WorkflowCore.Interface;
using WorkflowTest2.Models;

namespace WorkflowTest2.Workflow
{
    internal class SearchFilesWorkflow : IWorkflow<SearchFiles>
    {
        public string Id => "Searchfiles";

        public int Version => 1;

        public void Build(IWorkflowBuilder<SearchFiles> builder)
        {
            builder
                .StartWith<Search_StepBody>()
                .Input(step => step.SearchFolder, data => data.SearchFolder)
                .Output(data => data.Files, step => step.SearchFiles)
                .Then<FolderContains_StepBody>()
                .Input(step => step.InputFiles, data => data.Files)
                .Input(step => step.FolderContains, data => data.FolderContains)
                .Output(data => data.Files, step => step.OutputFiles);
        }
    }
}

第一个Input是把SearchFiles里面的属性SearchFolder，输入进“步骤主体”Search_StepBody中的公共属性SearchFolder。Output是把在Search_StepBody里搜索到的文件从公共属性SearchFiles输出到自定义数据SearchFiles的公共属性Files中。

完成后再启动第二个“步骤主体”FolderContains_StepBody，再从自定义数据SearchFiles中，把Files输入到InputFiles，把FolderContains输入到步骤主体的FolderContains，步骤主体完成后再从公共属性OutputFiles中输出到Files中，最后，SearchFiles.Files里就是我们要的结果。

更改Program.cs文件内空如下

using Microsoft.Extensions.DependencyInjection;
using WorkflowCore.Interface;
using WorkflowTest2.Models;
using WorkflowTest2.Workflow;

namespace WorkflowTest2
{
    internal class Program
    {
        static void Main(string[] args)
        {
            var provider = ConfigureServices();
            var host = provider.GetService<IWorkflowHost>();
            host.RegisterWorkflow<SearchFilesWorkflow, SearchFiles>();
            var searchFiles = new SearchFiles() { SearchFolder = @"D:\Company", Files = new List<SearchFile>(),FolderContains="公司|奖金" };
            host.Start();
            host.StartWorkflow("Searchfiles", searchFiles);
            Console.WriteLine("等待结果...");
            Console.ReadLine();
            Console.WriteLine($"总项数： {searchFiles.Files.Count}");
            searchFiles.Files.ForEach(f => Console.WriteLine($"{f.FullName}  => {f.IsDirectory}"));
            Console.ReadLine();
            Console.WriteLine("结束..");
            host.Stop();
        }

        private static IServiceProvider ConfigureServices()
        {
            IServiceCollection services = new ServiceCollection();
            services.AddLogging();
            services.AddWorkflow();
            return services.BuildServiceProvider();
        }
    }
}

最后运行结果：

 

 一个好的项目，肯定会用上工作流的，这个是跨平台的工作流，轻量，易用。