1 第一个简单的爬虫

注意，文档可能落后于代码，会有微小的差异，可以参考源码中的 Sample 项目一起学习使用。使用的 nuget 包也可能不是正式包。

1. .NET Core 的 Console 项目。

2. 添加 DotnetSpider 库

• Visual Studio

  + 右键解决方案并启动 Manage NuGet Packages(管理NuGet包)
  + 搜索 DotnetSpider，从结果列表中选中 DotnetSpider
  + 安装到项目
  

• Package Manager

  Install-Package DotnetSpider -Version 5.0.8
  

• 命令行

  dotnet add package DotnetSpider --version 5.0.8
  

3. 添加 Serilog 日志组件

    <PackageReference Include="Serilog.AspNetCore" Version="3.4.0" />
    <PackageReference Include="Serilog.Sinks.Console" Version="3.1.1" />
    <PackageReference Include="Serilog.Sinks.RollingFile" Version="3.3.0" />
    <PackageReference Include="Serilog.Sinks.PeriodicBatching" Version="2.3.0" />

4. 创建 GithubSpider 类

    public class GithubSpider : Spider
    {
    	public GithubSpider(IOptions<SpiderOptions> options, DependenceServices services, ILogger<Spider> logger) :
    		base(options, services, logger)
    	{
    	}
   
    	protected override async Task InitializeAsync(CancellationToken stoppingToken)
    	{
    		// 添加自定义解析
    		AddDataFlow(new Parser());
    		// 使用控制台存储器
    		AddDataFlow(new ConsoleStorage());
    		// 添加采集请求
    		await AddRequestsAsync(new Request("https://github.com/zlzforever")
    		{
    			// 请求超时 10 秒
    			Timeout = 10000
    		});
    	}
   
    	protected override SpiderId GenerateSpiderId()
    	{
    		return new(ObjectId.CreateId().ToString(), "Github");
    	}
   
    	class Parser : DataParser
    	{
    		public override Task InitializeAsync()
    		{
    			return Task.CompletedTask;
    		}
   
    		protected override Task ParseAsync(DataFlowContext context)
    		{
    			var selectable = context.Selectable;
    			// 解析数据
    			var author = selectable.XPath("//span[@class='p-name vcard-fullname d-block overflow-hidden']")
    				?.Value;
    			var name = selectable.XPath("//span[@class='p-nickname vcard-username d-block']")
    				?.Value;
    			context.AddData("author", author);
    			context.AddData("username", name);
    			return Task.CompletedTask;
    		}
    	}
    }

5. 在 Main 方法中添加如下代码

    	static async Task Main(string[] args)
    	{
    		ThreadPool.SetMaxThreads(255, 255);
    		ThreadPool.SetMinThreads(255, 255);
   
    		Log.Logger = new LoggerConfiguration()
    			.MinimumLevel.Information()
    			.MinimumLevel.Override("Microsoft.Hosting.Lifetime", LogEventLevel.Warning)
    			.MinimumLevel.Override("Microsoft", LogEventLevel.Warning)
    			.MinimumLevel.Override("System", LogEventLevel.Warning)
    			.MinimumLevel.Override("Microsoft.AspNetCore.Authentication", LogEventLevel.Warning)
    			.Enrich.FromLogContext()
    			.WriteTo.Console().WriteTo.RollingFile("logs/spider.log")
    			.CreateLogger();
   
    		var builder = Builder.CreateDefaultBuilder<GithubSpider>(options =>
    		{
    			// 每秒 1 个请求
    			options.Speed = 1;
    		});
    		builder.UseSerilog();
    		builder.UseQueueDistinctBfsScheduler<HashSetDuplicateRemover>();
    		await builder.Build().RunAsync();
   
    		Console.WriteLine("Bye!");
    	}

6. 运行程序

    [20:51:24 INF] 
    
      _____        _              _    _____       _     _
     |  __ \      | |            | |  / ____|     (_)   | |
     | |  | | ___ | |_ _ __   ___| |_| (___  _ __  _  __| | ___ _ __
     | |  | |/ _ \| __| '_ \ / _ \ __|\___ \| '_ \| |/ _` |/ _ \ '__|
     | |__| | (_) | |_| | | |  __/ |_ ____) | |_) | | (_| |  __/ |
     |_____/ \___/ \__|_| |_|\___|\__|_____/| .__/|_|\__,_|\___|_|     version: 5.0.8.0
                                            | |
                                            |_|
    
    [20:51:24 INF] RequestedQueueCount: 1000
    [20:51:24 INF] Depth: 0
    [20:51:24 INF] RetriedTimes: 3
    [20:51:24 INF] EmptySleepTime: 60
    [20:51:24 INF] Speed: 1
    [20:51:24 INF] Batch: 4
    [20:51:24 INF] RemoveOutboundLinks: False
    [20:51:24 INF] StorageType: DotnetSpider.MySql.MySqlEntityStorage, DotnetSpider.MySql
    [20:51:24 INF] RefreshProxy: 30
    [20:51:24 INF] Agent is starting
    [20:51:24 INF] Agent started
    [20:51:24 INF] Initialize spider 602e62cc5f337be5627cd768, Github
    [20:51:25 INF] 602e62cc5f337be5627cd768 DataFlows: Parser -> ConsoleStorage
    [20:51:25 INF] 602e62cc5f337be5627cd768 register topic DotnetSpider_602e62cc5f337be5627cd768
    [20:51:25 INF] Statistics service starting
    [20:51:25 INF] Statistics service started
    [20:51:30 INF] 602e62cc5f337be5627cd768 total 1, speed: 0, success 0, failure 0, left 1
    [20:51:31 INF] 602e62cc5f337be5627cd768 download https://github.com/zlzforever, l7nvHQ== completed
    
    DATA: {"username":"zlzforever","author":"Lewis Zou"}
    [20:51:35 INF] 602e62cc5f337be5627cd768 total 1, speed: 0.10, success 1, failure 0, left 0
    [20:51:40 INF] 602e62cc5f337be5627cd768 total 1, speed: 0.07, success 1, failure 0, left 0
    [20:52:28 INF] Statistics service stopping
    [20:52:28 INF] Statistics service stopped
    [20:52:28 INF] 602e62cc5f337be5627cd768 stopped
    [20:52:28 INF] Agent is stopping
    [20:52:28 INF] Agent stopped
    Bye!