命令行工具(CLI)
命令行工具(CLI)是在圖形用戶界面得到普及之前使用最為廣泛的用戶界面，它通常不支持鼠標，用戶通過鍵盤輸入指令，計算機接收到指令后，予以執行。
通常認為，命令行工具(CLI)沒有圖形用戶界面(GUI)那么方便用戶操作。因為，命令行工具的軟件通常需要用戶記憶操作的命令，但是，由於其本身的特點，命令行工具要較圖形用戶界面節約計算機系統的資源。在熟記命令的前提下，使用命令行工具往往要較使用圖形用戶界面的操作速度要快。所以，圖形用戶界面的操作系統中，都保留着可選的命令行工具。
另外，命令行工具(CLI)應該是一個開箱即用的工具，不需要安裝任何依賴。
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
指令設計
本文將使用.Net Core(版本3.1.102)編寫一個CLI工具，實現配置管理以及條目(item)管理(調用WebApi實現)，詳情如下：
框架說明
編寫CLI使用的主要框架是CommandLineUtils，它主要有以下優勢：
1. 良好的語法設計
2. 支持依賴注入
3. 支持generic host
WebApi
提供api讓cli調用，實現條目(item)的增刪改查：
[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 - 函數入口
[HelpOption(Inherited = true)] //顯示指令幫助，並且讓子指令也繼承此設置 [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) { //配置依賴注入 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) //處理未定義指令 { console.WriteLine(ex.Message); return -1; } } //指令邏輯 private int OnExecute(CommandLineApplication app, IConsole console) { console.WriteLine("Please specify a command."); app.ShowHelp(); return 1; } }
2. ConfigCommand和ItemCommand - 實現的功能比較簡單，主要是指令描述以及指定對應的子指令
[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 - 配置管理的具體實現，主要是文件讀寫
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 = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), _directoryName); if (!Directory.Exists(directory)) { Directory.CreateDirectory(directory); } var config = new Config { //彈出交互框，讓用戶輸入，設置默認值為http://localhost:5000/ Endpoint = Prompt.GetString("Specify the endpoint:", "http://localhost:5000/") }; if (!config.Endpoint.EndsWith("/")) { config.Endpoint += "/"; } var filePath = Path.Combine(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 = Path.Combine(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 - 調用Web Api的具體實現，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)); } }
如何發布
在項目文件中設置發布程序的名稱(AssemblyName)：
<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>netcoreapp3.1</TargetFramework>
<AssemblyName>api-cli</AssemblyName>
</PropertyGroup>
進入控制台程序目錄：
cd src/NetCoreCLI
發布Linux使用版本：
dotnet publish -c Release -r linux-x64 /p:PublishSingleFile=true
發布Windows使用版本：
dotnet publish -c Release -r win-x64 /p:PublishSingleFile=true
發布MAC使用版本：
dotnet publish -c Release -r osx-x64 /p:PublishSingleFile=true
使用示例
這里使用Linux作為示例環境。
1. 以docker的方式啟動web api
2. 虛擬機上沒有安裝.net core的環境
3. 把編譯好的CLI工具拷貝到虛擬機上，授權並移動到PATH中（如果不移動，可以通過./api-cli的方式調用）
4. 設置配置文件：api-cli config set
5. 查看配置文件：api-cli config get
6. 創建條目：api-cli item create
7. 條目列表：api-cli item list
8. 獲取條目：api-cli item get
9. 刪除條目：api-cli item delete
10. 指令幫助：api-cli -h， api-cli config -h， api-cli item -h
11. 錯誤指令：api-cli xxx
源碼地址
https://github.com/ErikXu/NetCoreCLI
參考資料
https://docs.microsoft.com/en-us/dotnet/core/rid-catalog#using-rids](https://docs.microsoft.com/en-us/dotnet/core/rid-catalog#using-rids
https://medium.com/swlh/build-a-command-line-interface-cli-program-with-net-core-428c4c85221