使用.Net Core编写命令行工具(CLI)

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 = Path.Combine(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 = 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 - 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));}
}

如何发布

　　在项目文件中设置发布程序的名称(AssemblyName)：

　<PropertyGroup><OutputType>Exe</OutputType><TargetFramework>netcoreapp3.1</TargetFramework><AssemblyName>api-cli</AssemblyName></PropertyGroup>

　　进入控制台程序目录：

cd src/NetCoreCLI

　　发布Linux使用版本：

dotnet publish -c Release -r linux-x64 /p:PublishSingleFile=true

　　发布Windows使用版本：

dotnet publish -c Release -r win-x64 /p:PublishSingleFile=true

　　发布MAC使用版本：

 dotnet publish -c Release -r osx-x64 /p:PublishSingleFile=true

使用示例

　　这里使用Linux作为示例环境。

　　1. 以docker的方式启动web api

　　2. 虚拟机上没有安装.net core的环境

　　3. 把编译好的CLI工具拷贝到虚拟机上，授权并移动到PATH中（如果不移动，可以通过./api-cli的方式调用）

  sudo chmod +x api-cli #授权sudo mv ./api-cli /usr/local/bin/api-cli #移动到PATH

　　4. 设置配置文件：api-cli config set

　　5. 查看配置文件：api-cli config get

　　6. 创建条目：api-cli item create

　　7. 条目列表：api-cli item list

　　8. 获取条目：api-cli item get

　　9. 删除条目：api-cli item delete

　　10. 指令帮助：api-cli -h， api-cli config -h， api-cli item -h

　　11. 错误指令：api-cli xxx

源码地址

　　https://github.com/ErikXu/NetCoreCLI

参考资料

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

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