在AutoCompleteBox组件中集成搜索引擎的功能是十分常见的，这有助于我们更好地与Web进行交互。本文将为大家讲述如何在在AutoCompleteBox组件中集成搜索引擎的搜索建议。

 

实例：

说明：本实例用的搜索引擎是微软的Bing(必应)

详细的说明在代码中给出。

WebServiceHelper.cs(业务辅助类)文件代码：

using System;

using System.Collections.Generic;

using System.Linq;

using System.Globalization;

using System.Diagnostics.CodeAnalysis;

using System.Net;

using System.Windows.Browser;

using System.Windows.Controls;

 

namespace SilverlightClient

{

   public static class WebServiceHelper

    {

        private const string LiveSuggestionsJsonUriFormat = "http://api.search.live.net/qson.aspx?query={0}";

        private const string LiveSearchUriFormat = "http://search.live.com/results.aspx?q={0}";

       

        public static bool CanMakeHttpRequests

        {

            get

            {

                if (!HtmlPage.IsEnabled)

                {

                    return false;

                }

 

                string scheme = HtmlPage.Document.DocumentUri.Scheme ?? string.Empty;

                return string.Compare(scheme, "http", StringComparison.OrdinalIgnoreCase) == 0;

            }

        }

 

        public static Uri CreateWebSearchUri(string searchText)

        {

            return new Uri(string.Format(CultureInfo.InvariantCulture, LiveSearchUriFormat, HttpUtility.UrlEncode(searchText)));

        }

 

        public static Uri CreateWebSearchSuggestionsUri(string searchText)

        {

            return new Uri(string.Format(CultureInfo.InvariantCulture, LiveSuggestionsJsonUriFormat, HttpUtility.UrlEncode(searchText)));

        }

    }

}

 

MainPage.xaml文件代码：

<UserControl

    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"

    mc:Ignorable="d" xmlns:input="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Input" x:Class="SilverlightClient.MainPage"

    d:DesignWidth="320" d:DesignHeight="240">

    <Grid x:Name="LayoutRoot" Width="320" Height="240" Background="White">

 

        <TextBlock Height="26" HorizontalAlignment="Left" Margin="8,8,0,0" VerticalAlignment="Top" Width="120" FontSize="16" Text="请输入搜索词：" TextWrapping="Wrap"/>

        <input:AutoCompleteBox x:Name="Search" FontSize="14" FilterMode="None" Height="26" Margin="8,55,112,0" VerticalAlignment="Top" Width="200"/>

        <Button x:Name="GoSearch" Height="26" HorizontalAlignment="Right" Margin="0,55,34,0" VerticalAlignment="Top" Width="74" Content="Search!" FontSize="13.333"/>

 

    </Grid>

</UserControl>

 

MainPage.xaml.cs文件代码：

using System;

using System.Collections.Generic;

using System.Diagnostics.CodeAnalysis;

using System.Json;

using System.Linq;

using System.Net;

using System.Windows;

using System.Windows.Browser;

using System.Windows.Controls;

using System.ComponentModel;

 

namespace SilverlightClient

{

    public partial class MainPage : UserControl

    {

        public MainPage()

        {

            InitializeComponent();

            //注册事件触发处理

            this.Loaded += new RoutedEventHandler(MainPage_Loaded);

        }

 

        void MainPage_Loaded(object sender, RoutedEventArgs e)

        {

            if (WebServiceHelper.CanMakeHttpRequests)//如果能做Http请求

            {

                //注册AutoCompleteBox组件的下拉框内容正在生成事件触发处理

                Search.Populating += Search_Populating;

                //建立打开结果窗口的事件委托

                Action go = () => HtmlPage.Window.Navigate(WebServiceHelper.CreateWebSearchUri(Search.Text), "_blank");

                //注册AutoCompleteBox组件的KeyUp事件触发处理。当按下Enter键时，相当于提交

                Search.KeyUp += (s, args) =>

                {

                    if (args.Key == System.Windows.Input.Key.Enter)

                    {

                        go();

                    }

                };

                //搜素按钮的事件触发处理

                GoSearch.Click += (s, args) => go();

            }

        }

 

        private void Search_Populating(object sender, PopulatingEventArgs e)

        {

            AutoCompleteBox autoComplete = (AutoCompleteBox)sender;

 

            //等待结果

            e.Cancel = true;

 

            //创建一个搜索建议请求

            WebClient wc = new WebClient();

            wc.DownloadStringCompleted += OnDownloadStringCompleted;

            wc.DownloadStringAsync(WebServiceHelper.CreateWebSearchSuggestionsUri(autoComplete.SearchText), autoComplete);

        }

 

        private void OnDownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)

        {

            AutoCompleteBox autoComplete = e.UserState as AutoCompleteBox;

           

            if (autoComplete != null && e.Error == null && !e.Cancelled && !string.IsNullOrEmpty(e.Result))//如果没有出现异常情况的话

            {

                List<string> data = new List<string>();

                try

                {

                    JsonObject jso = ((JsonObject)JsonObject.Parse(e.Result))["SearchSuggestion"] as JsonObject;//创建Json对象

                    string originalSearchString = jso["Query"];//原始查询字符串

                    if (originalSearchString == autoComplete.SearchText)

                    {

                        foreach (JsonObject suggestion in (JsonArray)jso["Section"])

                        {

                            data.Add(suggestion.Values.First());

                        }

                       

                        autoComplete.ItemsSource = data;//填充AutoCompleteBox组件的数据源

                        autoComplete.PopulateComplete();//结束AutoCompleteBox组件的下拉框内容生成

                    }

                }

                catch

                {

                }

            }

        }

    }

}

 

最终效果图：