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 5.0.0-beta1
  

• 命令行

  dotnet add package DotnetSpider --version 5.0.0-beta1
  

3. 添加 Serilog 日志组件

   <PackageReference Include="Serilog.AspNetCore" Version="3.2.0"/>
   <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, SpiderServices 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("https://github.com/zlzforever");
           }
   
           protected override (string Id, string Name) GetIdAndName()
           {
               return (Guid.NewGuid().ToString("N"), "Github");
           }
   
           class Parser : DataParser
           {
               protected override Task Parse(DataContext 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)
           {
               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/spiders.log")
                   .CreateLogger();
   
               var builder = Builder.CreateDefaultBuilder<GithubSpider>(options =>
               {
                   // 每秒 1 个请求
                   options.Speed = 1;
                   // 请求超时
                   options.RequestTimeout = 10;
               });
               builder.UseSerilog();
               builder.UseQueueDistinctBfsScheduler<HashSetDuplicateRemover>();
               await builder.Build().RunAsync();
               Environment.Exit(0);
           }

6. 运行程序

   [17:36:53 INF] Argument: RequestedQueueCount, 100
   [17:36:53 INF] Argument: Depth, 0
   [17:36:53 INF] Argument: RequestTimeout, 10
   [17:36:53 INF] Argument: RetriedTimes, 3
   [17:36:53 INF] Argument: EmptySleepTime, 10
   [17:36:53 INF] Argument: Speed, 1
   [17:36:53 INF] Argument: ProxyTestUri, http://www.baidu.com
   [17:36:53 INF] Argument: ProxySupplierUri, 
   [17:36:53 INF] Argument: UseProxy, False
   [17:36:53 INF] Argument: RemoveOutboundLinks, False
   [17:36:53 INF] Argument: StorageConnectionString, 
   [17:36:53 INF] Argument: Storage, 
   [17:36:53 INF] Argument: ConnectionString, 
   [17:36:53 INF] Argument: Database, dotnetspider
   [17:36:53 INF] Argument: StorageMode, InsertIgnoreDuplicate
   [17:36:53 INF] Argument: MySqlFileType, LoadFile
   [17:36:53 INF] Argument: SqlServerVersion, V2000
   [17:36:53 INF] Argument: HBaseRestServer, 
   [17:36:53 INF] None proxy supplier
   [17:36:53 INF] Statistics service starting
   [17:36:53 INF] Agent register service starting
   [17:36:53 INF] Statistics service started
   [17:36:53 INF] Agent register service started
   [17:36:53 INF] Agent starting
   [17:36:54 INF] Initialize d9531ecc28a5492ab58e9d8b47a6bf05, Github
   [17:36:54 INF] Agent started
   [17:36:54 INF] d9531ecc28a5492ab58e9d8b47a6bf05, Github DataFlows: Parser -> ConsoleStorage
   [17:36:54 INF] Register topic DOTNET_SPIDER_D9531ECC28A5492AB58E9D8B47A6BF05
   [17:36:54 INF] d9531ecc28a5492ab58e9d8b47a6bf05, Github started
   [17:36:56 INF] https://github.com/zlzforever download success
   [{"Key":"username","Value":"zlzforever"},{"Key":"author","Value":"Lewis Zou"}]
   [17:36:58 INF] d9531ecc28a5492ab58e9d8b47a6bf05 total 1, success 1, failed 0, left 0
   [17:37:03 INF] d9531ecc28a5492ab58e9d8b47a6bf05 total 1, success 1, failed 0, left 0
   [17:37:05 INF] d9531ecc28a5492ab58e9d8b47a6bf05, Github stopping
   [17:37:05 INF] d9531ecc28a5492ab58e9d8b47a6bf05, Github stopped
   [17:37:05 INF] Agent stopping
   [17:37:05 INF] Agent stopped
   [17:37:05 INF] Agent register service stopping
   [17:37:05 INF] Agent register service stopped
   [17:37:05 INF] Statistics service stopping
   [17:37:05 INF] Statistics service stopped