1500字范文 > 使用.Net Core编写命令行工具(CLI)

使用.Net Core编写命令行工具(CLI)

时间：2022-07-23 02:16:46

命令行工具(CLI)

命令行工具(CLI)是在图形用户界面得到普及之前使用最为广泛的用户界面，它通常不支持鼠标，用户通过键盘输入指令，计算机接收到指令后，予以执行。

通常认为，命令行工具(CLI)没有图形用户界面(GUI)那么方便用户操作。因为，命令行工具的软件通常需要用户记忆操作的命令，但是，由于其本身的特点，命令行工具要较图形用户界面节约计算机系统的资源。在熟记命令的前提下，使用命令行工具往往要较使用图形用户界面的操作速度要快。所以，图形用户界面的操作系统中，都保留着可选的命令行工具。

另外，命令行工具(CLI)应该是一个开箱即用的工具，不需要安装任何依赖。

一些熟悉的CLI工具如下：

1.dotnet cli

2.vue cli

3.angular cli

4.aws cli

5.azure cli

指令设计

本文将使用.Net Core(版本3.1.102)编写一个CLI工具，实现配置管理以及条目(item)管理(调用WebApi实现)，详情如下：

框架说明

编写CLI使用的主要框架是CommandLineUtils，它主要有以下优势：

1. 良好的语法设计

2. 支持依赖注入

3. 支持generic host

WebApi

提供api让cli调用，实现条目(item)的增删改查：

[Route("api/items")][ApiController]public class ItemsController : ControllerBase{ private readonly IMemoryCache _cache; private readonly string _key = "items"; public ItemsController(IMemoryCache memoryCache){_cache = memoryCache;}[HttpGet] public IActionResult List(){ var items = _cache.Get<List<Item>>(_key); return Ok(items);}[HttpGet("{id}")] public IActionResult Get(string id){ var item = _cache.Get<List<Item>>(_key).FirstOrDefault(n => n.Id == id); return Ok(item);}[HttpPost] public IActionResult Create(ItemForm form){ var items = _cache.Get<List<Item>>(_key) ?? new List<Item>(); var item = new Item{Id = Guid.NewGuid().ToString("N"),Name = form.Name,Age = form.Age};items.Add(item);_cache.Set(_key, items); return Ok(item);}[HttpDelete("{id}")] public IActionResult Delete(string id){ var items = _cache.Get<List<Item>>(_key); var item = items?.SingleOrDefault(n => n.Id == id); if (item == null){ return NotFound();}items.Remove(item);_cache.Set(_key, items); return Ok();}}

CLI

Program - 函数入口

[HelpOption(Inherited = true)] //显示指令帮助，并且让子指令也继承此设置[Command(Description = "A tool to communicate with web api"), //指令描述Subcommand(typeof(ConfigCommand), typeof(ItemCommand))] //子指令class Program{ public static int Main(string[] args){//配置依赖注入 var serviceCollection = new ServiceCollection();serviceCollection.AddSingleton(PhysicalConsole.Singleton);serviceCollection.AddSingleton<IConfigService, ConfigService>();serviceCollection.AddHttpClient<IItemClient, ItemClient>(); var services = serviceCollection.BuildServiceProvider(); var app = new CommandLineApplication<Program>();app.Conventions.UseDefaultConventions().UseConstructorInjection(services); var console = (IConsole)services.GetService(typeof(IConsole)); try{ return app.Execute(args);} catch (UnrecognizedCommandParsingException ex) //处理未定义指令{console.WriteLine(ex.Message); return -1;}}//指令逻辑 private int OnExecute(CommandLineApplication app, IConsole console){console.WriteLine("Please specify a command.");app.ShowHelp(); return 1;}}

2. ConfigCommand和ItemCommand - 实现的功能比较简单，主要是指令描述以及指定对应的子指令

[Command("config", Description = "Manage config"),Subcommand(typeof(GetCommand), typeof(SetCommand))]public class ConfigCommand{ private int OnExecute(CommandLineApplication app, IConsole console){console.Error.WriteLine("Please submit a sub command.");app.ShowHelp(); return 1;}}[Command("item", Description = "Manage item"),Subcommand(typeof(CreateCommand), typeof(GetCommand), typeof(ListCommand), typeof(DeleteCommand))]public class ItemCommand{ private int OnExecute(CommandLineApplication app, IConsole console){console.Error.WriteLine("Please submit a sub command.");app.ShowHelp(); return 1;}}

3.ConfigService - 配置管理的具体实现，主要是文件读写

public interface IConfigService{ void Set();Config Get();}public class ConfigService: IConfigService{ private readonly IConsole _console; private readonly string _directoryName; private readonly string _fileName; public ConfigService(IConsole console){_console = console;_directoryName = ".api-cli";_fileName = "config.json";} public void Set(){ var directory = bine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), _directoryName); if (!Directory.Exists(directory)){Directory.CreateDirectory(directory);} var config = new Config{//弹出交互框，让用户输入，设置默认值为http://localhost:5000/Endpoint = Prompt.GetString("Specify the endpoint:", "http://localhost:5000/")}; if (!config.Endpoint.EndsWith("/")){config.Endpoint += "/";} var filePath = bine(directory, _fileName); using (var outputFile = new StreamWriter(filePath, false, Encoding.UTF8)){outputFile.WriteLine(JsonConvert.SerializeObject(config, Formatting.Indented));}_console.WriteLine($"Config saved in {filePath}.");} public Config Get(){ var filePath = bine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), _directoryName, _fileName); if (File.Exists(filePath)){ var content = File.ReadAllText(filePath); try{var config = JsonConvert.DeserializeObject<Config>(content);return config;} catch{_console.WriteLine("The config is invalid, please use 'config set' command to reset one.");}} else{_console.WriteLine("Config is not existed, please use 'config set' command to set one.");} return null;}}

4.ItemClient - 调用Web Api的具体实现，使用HttpClientFactory的方式

public interface IItemClient{Task<string> Create(ItemForm form);Task<string> Get(string id);Task<string> List();Task<string> Delete(string id);}public class ItemClient : IItemClient{ public HttpClient Client { get; } public ItemClient(HttpClient client, IConfigService configService){ var config = configService.Get(); if (config == null){ return;}client.BaseAddress = new Uri(config.Endpoint);Client = client;} public async Task<string> Create(ItemForm form){ var content = new StringContent(JsonConvert.SerializeObject(form), Encoding.UTF8, "application/json"); var result = await Client.PostAsync("/api/items", content); if (result.IsSuccessStatusCode){ var stream = await result.Content.ReadAsStreamAsync(); var item = Deserialize<Item>(stream); return $"Item created, info:{item}";} return "Error occur, please again later.";} public async Task<string> Get(string id){ var result = await Client.GetAsync($"/api/items/{id}"); if (result.IsSuccessStatusCode){ var stream = await result.Content.ReadAsStreamAsync(); var item = Deserialize<Item>(stream); var response = new StringBuilder();response.AppendLine($"{"Id".PadRight(40, ' ')}{"Name".PadRight(20, ' ')}Age");response.AppendLine($"{item.Id.PadRight(40, ' ')}{item.Name.PadRight(20, ' ')}{item.Age}"); return response.ToString();} return "Error occur, please again later.";} public async Task<string> List(){ var result = await Client.GetAsync($"/api/items"); if (result.IsSuccessStatusCode){ var stream = await result.Content.ReadAsStreamAsync(); var items = Deserialize<List<Item>>(stream); var response = new StringBuilder();response.AppendLine($"{"Id".PadRight(40, ' ')}{"Name".PadRight(20, ' ')}Age"); if (items != null && items.Count > 0){foreach (var item in items){response.AppendLine($"{item.Id.PadRight(40, ' ')}{item.Name.PadRight(20, ' ')}{item.Age}");}} return response.ToString();} return "Error occur, please again later.";} public async Task<string> Delete(string id){ var result = await Client.DeleteAsync($"/api/items/{id}"); if (result.IsSuccessStatusCode){ return $"Item {id} deleted.";} if (result.StatusCode == HttpStatusCode.NotFound){ return $"Item {id} not found.";} return "Error occur, please again later.";} private static T Deserialize<T>(Stream stream){ using var reader = new JsonTextReader(new StreamReader(stream)); var serializer = new JsonSerializer(); return (T)serializer.Deserialize(reader, typeof(T));}}