c# WPF——完成一个简单的百度贴吧爬虫客户端

话不多说先上图

爬取10页大概500个帖子大概10s,500页2w多个帖子大概2min,由此可见性能并不是特别好，但是也没有很差。

好了话不多说，我们来一步一步实现这么个简易的客户端。

1.创建项目

创建一个WPF空项目，导入需要的Devexpress的dll

Devexpress可以到官网下载，基本16版本以上都可以。下载试用版的也可以，基本到期也不会限制你使用，只有开发的时候会弹出框，叉掉即可，比较良心。

下载地址:https://www.devexpress.com/

 2.编辑界面

基本就是xaml代码的编写，DevExpress的demo中心也有很多样例，直接上代码。

<dx:ThemedWindow x:Class="SearchAnyWay.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:dx="http://schemas.devexpress.com/winfx/2008/xaml/core"
        xmlns:dxmvvm="http://schemas.devexpress.com/winfx/2008/xaml/mvvm"
        xmlns:dxe="http://schemas.devexpress.com/winfx/2008/xaml/editors"
        xmlns:dxlc="http://schemas.devexpress.com/winfx/2008/xaml/layoutcontrol"
        xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid"
        xmlns:local="clr-namespace:SearchAnyWay"
        mc:Ignorable="d"
        Title="百度贴吧搜索神器(v1.0)" Height="600" Width="800">
    <Grid>
        <dxlc:LayoutControl VerticalAlignment="Stretch" Orientation="Vertical" TextBlock.FontSize="11">
            <Label VerticalAlignment="Top" FontWeight="Bold" Content="输入您需要查找的关键字"></Label>
            <dxlc:LayoutGroup Orientation="Horizontal">
                <dxlc:LayoutItem Label="关键字(K)" AddColonToLabel="True">
                    <dxe:TextEdit EditValue="{Binding Path=Name, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}" >
                        <dxmvvm:Interaction.Triggers>
                            <dxmvvm:KeyToCommand KeyGesture="Enter" Command="{Binding SearchCommand}"></dxmvvm:KeyToCommand>
                        </dxmvvm:Interaction.Triggers>
                    </dxe:TextEdit>
                </dxlc:LayoutItem>
                <dxlc:LayoutItem Label="贴吧名(N)" AddColonToLabel="True">
                    <dxe:TextEdit EditValue="{Binding Path=HubName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}">
                    </dxe:TextEdit>
                </dxlc:LayoutItem>
                <dxlc:LayoutItem Label="爬取页数(P)" AddColonToLabel="True">
                    <dxe:ComboBoxEdit ItemsSource="{Binding PageRange}"
                                      SelectedItem="{Binding Page}"
                                      ShowSizeGrip="False"
                                      IsTextEditable="False">
                    </dxe:ComboBoxEdit>
                </dxlc:LayoutItem>
                <dxlc:LayoutGroup HorizontalAlignment="Right" VerticalAlignment="Center">
                    <dx:SimpleButton x:Name="btnSearch" Content="查找(S)" Width="80" Command="{Binding SearchCommand}"></dx:SimpleButton>

                </dxlc:LayoutGroup>
            </dxlc:LayoutGroup>
            <dxg:TreeListControl x:Name="treeList"  Margin="0,10" ItemsSource="{Binding Source}"
                                         SelectionMode="Row" SelectedItem="{Binding SelectedRow}">
                <dxg:TreeListControl.Columns>
                    <dxg:TreeListColumn  FieldName="Title" Header="标题"  Width="2*"/>
                    <dxg:TreeListColumn  FieldName="Brief" Width="2*" Header="详情"/>
                    <dxg:TreeListColumn Header="回复数" FieldName="CommentCount" Width="*"/>
                    <dxg:TreeListColumn Header="作者" FieldName="AuthorName" Width="*"/>
                </dxg:TreeListControl.Columns>
                <dxg:TreeListControl.View>
                    <dxg:TreeListView x:Name="view" VerticalScrollbarVisibility="Auto" AutoExpandAllNodes="True"  AllowEditing="False" NavigationStyle="Row" ShowIndicator="False"  TreeDerivationMode="ChildNodesSelector" ChildNodesPath="ICDItems">
                        <dxmvvm:Interaction.Triggers>
                            <dxmvvm:EventToCommand EventName="SourceUpdated" Command="{Binding Commands.ExpandAllNodes, ElementName=view}" />
                            <dxmvvm:EventToCommand EventName="RowDoubleClick" Command="{Binding SearchCommand}" CommandParameter="{Binding ElementName=treeList,Path=SelectedItem}" />
                        </dxmvvm:Interaction.Triggers>
                    </dxg:TreeListView>
                </dxg:TreeListControl.View>
            </dxg:TreeListControl>
            <dxlc:LayoutGroup VerticalAlignment="Bottom" Orientation="Horizontal">
                <Label Content="帖子总数:" HorizontalAlignment="Right"/>
                <Label Content="{Binding Source.Count, UpdateSourceTrigger=PropertyChanged}"  HorizontalAlignment="Right">
                    </Label>
            </dxlc:LayoutGroup>
            <dxlc:LayoutGroup VerticalAlignment="Bottom" Orientation="Horizontal">
                <dxe:CheckEdit IsChecked="{Binding IsAll}"  Content="Include All" HorizontalAlignment="Left"/>
                <dx:SimpleButton Content="Copy VLPath To Clipboard" IsEnabled="{Binding CanNext}" Command="{Binding CopyVLPathCommand}" HorizontalAlignment="Left"></dx:SimpleButton>
                <dxlc:LayoutGroup HorizontalAlignment="Right">
                    <dx:SimpleButton Content="下载(D)" Width="80" IsEnabled="{Binding CanNext}" Command="{Binding NextCommand}"></dx:SimpleButton>
                    <dx:SimpleButton Content="清除(C)" Width="80" IsEnabled="{Binding CanNext}" Command="{Binding OKCommand}"></dx:SimpleButton>
                    <dx:SimpleButton Content="合作(P)" Width="80" Command="{Binding CancelCommand}"></dx:SimpleButton>
                </dxlc:LayoutGroup>
            </dxlc:LayoutGroup>
        </dxlc:LayoutControl>
        <dx:WaitIndicator  DeferedVisibility="{Binding IsLoading}" />
    </Grid>
</dx:ThemedWindow>

3.实现mvvm模式。

这里采用了DevExpress自带的的mvvm模式，和WPF自带的去创建的框架基本一致。不了解mvvm的同学可以去园子里看看相关文章。

（1）后台代码设置主题还有绑定视图模型。

public partial class MainWindow
    {
        public MainWindow()
        {
            InitializeComponent();
            //设置样式
            ApplicationThemeHelper.UseLegacyDefaultTheme = true;
            ApplicationThemeHelper.ApplicationThemeName = Theme.VisualStudioCategory;
            this.WindowStyle = System.Windows.WindowStyle.SingleBorderWindow;
            this.Icon = new BitmapImage(new Uri("../../debug.png",UriKind.Relative));
            this.BorderThickness = new Thickness();
            this.Margin = new Thickness();
            this.Padding = new Thickness();
            this.DataContext = new MainViewModel();
        }
    }

( 2 ) 设计帖子的实体类。

可以根据自己想要爬取的信息设计。

 public class ArticleModel
    {
        public string Title { get; set; }
        public string Brief { get; set; }
        public int CommentCount { get; set; }
        public string AuthorName { get; set; }
    }

（3）页数，帖子集合，等属性在ViewModel中进行声明。

//加载中
        private bool _loading;
        public bool IsLoading
        {
            get { return this._loading; }
            set
            {
                SetProperty(ref _loading, value, () => IsLoading);
            }
        }
        //贴吧名
        private string _hub;
        public string HubName
        {
            get { return this._hub; }
            set
            {
                SetProperty(ref _hub, value, () => HubName);
            }
        }
        //爬取页数
        private int _page;
        public int Page
        {
            get { return this._page; }
            set
            {
                SetProperty(ref _page, value, () => Page);
            }
        }
        //帖子集合
        public ObservableCollection<ArticleModel> _source;
        public ObservableCollection<ArticleModel> Source
        {
            get { return _source; }
            set { SetProperty(ref _source, value, ()=>Source); }
        }

（3）查询业务绑定到按钮的Command,下拉列表的绑定等。

public AsyncCommand SearchCommand { get; set; }

public IEnumerable<int> PageRange { get; private set; }

public MainViewModel()
        {
            Page = ;
            PageRange = new List<int>() { ,, , , , ,  };
            Source = new ObservableCollection<ArticleModel>();
            SearchCommand = new AsyncCommand(Search);
        }

4.爬虫业务的简单实现

我们使用HttpClient进行请求获取html页面的代码

使用AngleSharp解析html示例代码（按Ctrl+Shift+P快速安装NuGet包）:Install-Package AngleSharp

相关简单使用：

//获取请求后response的页面代码。
                                string pageData = await http.GetStringAsync($"https://tieba.baidu.com/f?kw={HubName}&ie=utf-8&pn={pnIndex}");

//AngleSharp解析页面代码
                                IHtmlDocument doc = await parser.ParseDocumentAsync(pageData);

5.分析百度贴吧

可以看到URL基本一致，主要是一个URL参数会跟着页数而变化就是pn(Page Number),规律就是(Page-1)*50。50大概就是每页有50个帖子

那我们就好处理了，获取每个帖子的节点然后再去依次查找我们所需要的数据就可以了。

爬取的核心代码如下

await Task.Run(() =>
                {
                    var http = new HttpClient();
                    var parser = new HtmlParser();
                    var result=Enumerable.Range(, Page)
                        .AsParallel()
                        .AsOrdered()
                        .SelectMany(page =>
                        {
                            return Task.Run(async () =>
                            {
                                var pnIndex = page * ;
                                //获取请求后response的页面代码。
                                string pageData = await http.GetStringAsync($"https://tieba.baidu.com/f?kw={HubName}&ie=utf-8&pn={pnIndex}".Dump());
                                //AngleSharp解析页面代码
                                IHtmlDocument doc = await parser.ParseDocumentAsync(pageData);
                                return doc.QuerySelectorAll(".t_con.cleafix").Select(tag => new ArticleModel()
                                {
                                    Title = tag.QuerySelector(".j_th_tit").TextContent?.Trim(),
                                    Brief= tag.QuerySelector(".threadlist_abs.threadlist_abs_onlyline")?.TextContent?.Trim(),
                                    CommentCount=Convert.ToInt32(tag.QuerySelector(".threadlist_rep_num.center_text")?.TextContent),
                                    AuthorName=tag.QuerySelector(".frs-author-name.j_user_card")?.TextContent?.Trim(),
                                }); ;
                            }).GetAwaiter().GetResult();
                        });
                    Source = new ObservableCollection<ArticleModel>(result);
                });

一个小细节就是dom元素如果class中有空格查找的时候一定要用'.'来代替，比如dom元素class是'ftt poot'那么查找的时候就应该是tag.QuerySelector(".ftt.poot")坑里了我很久！！！可能是我这方面没怎么接触过吧。。。

好了，爬取的功能完成了，其他的边角料就自己随意发挥吧，哈哈。

代码下载地址:https://github.com/BruceQiu1996/WPF-/tree/master