Flutter书籍信息抓取插件book_scraper的使用

在本篇文档中，我们将详细介绍如何使用Flutter中的书籍信息抓取插件book_scraper。该插件可以帮助你从流行的图书网站上抓取书籍信息。

特性

• 帮助抓取图书网站。
• 帮助解析抓取到的图书数据。
• 安全地解析抓取到的图书结果。

开始使用

首先，你需要在你的项目中添加book_scraper依赖。打开pubspec.yaml文件，并添加以下内容：

dependencies:
  book_scraper: ^x.x.x

然后运行flutter pub get以安装依赖。

使用示例

接下来，我们通过一个简单的例子来展示如何使用book_scraper插件。

示例代码

import 'package:flutter/material.dart';
import 'package:book_scraper/book_scraper.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text('书籍信息抓取示例')),
        body: Center(
          child: BookScraperExample(),
        ),
      ),
    );
  }
}

class BookScraperExample extends StatefulWidget {
  @override
  _BookScraperExampleState createState() => _BookScraperExampleState();
}

class _BookScraperExampleState extends State<BookScraperExample> {
  List<Map<String, dynamic>> books = [];

  @override
  void initState() {
    super.initState();
    fetchBooks();
  }

  Future<void> fetchBooks() async {
    try {
      final response = await AudioBookBayApi().find('哈利波特');
      setState(() {
        books = response['books'];
      });
    } catch (e) {
      print('Error fetching books: $e');
    }
  }

  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      itemCount: books.length,
      itemBuilder: (context, index) {
        final book = books[index];
        return ListTile(
          title: Text(book['title']),
          subtitle: Text(book['category']),
          leading: Image.network(book['coverUrl'], width: 50),
          trailing: ElevatedButton(
            onPressed: () {
              // 打开详情页面
            },
            child: Text('查看详情'),
          ),
        );
      },
    );
  }
}

class AudioBookBayApi extends BaseBookApi {
  @override
  String get baseUrl => 'https://some_book_website';

  /// 返回基于搜索请求的一系列书籍。
  Future<SearchResponse<T>> find(String query) async {
    try {
      final searchTermQuery = '?s=${Uri.encodeComponent(query.trim())}';

      final url = '$baseUrl/$searchTermQuery';
      final soup = await cookSoup(url);

      // 从抓取的结果中检索元素
      final resultContainer = soup.find(
        'div',
        class_: 'some div claas definition',
      );

      final books = resultContainer?.findAll('article');

      final conversionBookRequest = ConversionRequest<T, Bs4Element>(
        List<Bs4Element>.from(books ?? []),
        _getBookfromScrapedHtml,
      );

      return compute(
        convertListToModelWithErrorCount<T, Bs4Element>,
        conversionBookRequest,
      ).then((result) {
        return {
          'total': result.results.length,
          'books': result.results,
        };
      });
    } catch (e) {
      throw Exception('Error finding books');
    }
  }

  T _getBookfromScrapedHtml(Bs4Element soupElement) {
    String getTitle() {
      return soupElement
              .find(
                'h2',
                class_: 'mb15 mt0 font110 mobfont100 fontnormal lineheight20',
              )
              ?.string
              .trim() ??
          '';
    }

    String getDetailsUrl() {
      return soupElement.a?.attributes['href'] ?? '';
    }

    String getCoverUrl() {
      return soupElement.a?.children.first.attributes['src'] ?? '';
    }

    String getCategory() {
      return soupElement
              .find(
                'span',
                class_: 'cat_link_meta',
              )
              ?.a
              ?.text ??
          '';
    }

    final title = getTitle();
    final detailsUrl = getDetailsUrl();
    final category = getCategory();
    final coverUrl = getCoverUrl();

    return T(
      title: title,
      category: category,
      coverUrl: coverUrl,
      detailsUrl: detailsUrl,
    );
  }
}

代码解释

1. 导入必要的包：

   import 'package:flutter/material.dart';
   import 'package:book_scraper/book_scraper.dart';
   

2. 创建主应用：

   void main() {
     runApp(MyApp());
   }
   

3. 定义主应用UI：

   class MyApp extends StatelessWidget {
     @override
     Widget build(BuildContext context) {
       return MaterialApp(
         home: Scaffold(
           appBar: AppBar(title: Text('书籍信息抓取示例')),
           body: Center(
             child: BookScraperExample(),
           ),
         ),
       );
     }
   }
   

4. 创建书籍抓取示例组件：

   class BookScraperExample extends StatefulWidget {
     @override
     _BookScraperExampleState createState() => _BookScraperExampleState();
   }
   

5. 实现书籍抓取逻辑：

   class _BookScraperExampleState extends State<BookScraperExample> {
     List<Map<String, dynamic>> books = [];
   
     @override
     void initState() {
       super.initState();
       fetchBooks();
     }
   
     Future<void> fetchBooks() async {
       try {
         final response = await AudioBookBayApi().find('哈利波特');
         setState(() {
           books = response['books'];
         });
       } catch (e) {
         print('Error fetching books: $e');
       }
     }
   
     @override
     Widget build(BuildContext context) {
       return ListView.builder(
         itemCount: books.length,
         itemBuilder: (context, index) {
           final book = books[index];
           return ListTile(
             title: Text(book['title']),
             subtitle: Text(book['category']),
             leading: Image.network(book['coverUrl'], width: 50),
             trailing: ElevatedButton(
               onPressed: () {
                 // 打开详情页面
               },
               child: Text('查看详情'),
             ),
           );
         },
       );
     }
   }
   

6. 定义抓取API：

   class AudioBookBayApi extends BaseBookApi {
     @override
     String get baseUrl => 'https://some_book_website';
   
     /// 返回基于搜索请求的一系列书籍。
     Future<SearchResponse<T>> find(String query) async {
       try {
         final searchTermQuery = '?s=${Uri.encodeComponent(query.trim())}';
   
         final url = '$baseUrl/$searchTermQuery';
         final soup = await cookSoup(url);
   
         // 从抓取的结果中检索元素
         final resultContainer = soup.find(
           'div',
           class_: 'some div claas definition',
         );
   
         final books = resultContainer?.findAll('article');
   
         final conversionBookRequest = ConversionRequest<T, Bs4Element>(
           List<Bs4Element>.from(books ?? []),
           _getBookfromScrapedHtml,
         );
   
         return compute(
           convertListToModelWithErrorCount<T, Bs4Element>,
           conversionBookRequest,
         ).then((result) {
           return {
             'total': result.results.length,
             'books': result.results,
           };
         });
       } catch (e) {
         throw Exception('Error finding books');
       }
     }
   
     T _getBookfromScrapedHtml(Bs4Element soupElement) {
       String getTitle() {
         return soupElement
                 .find(
                   'h2',
                   class_: 'mb15 mt0 font110 mobfont100 fontnormal lineheight20',
                 )
                 ?.string
                 .trim() ??
             '';
       }
   
       String getDetailsUrl() {
         return soupElement.a?.attributes['href'] ?? '';
       }
   
       String getCoverUrl() {
         return soupElement.a?.children.first.attributes['src'] ?? '';
       }
   
       String getCategory() {
         return soupElement
                 .find(
                   'span',
                   class_: 'cat_link_meta',
                 )
                 ?.a
                 ?.text ??
             '';
       }
   
       final title = getTitle();
       final detailsUrl = getDetailsUrl();
       final category = getCategory();
       final coverUrl = getCoverUrl();
   
       return T(
         title: title,
         category: category,
         coverUrl: coverUrl,
         detailsUrl: detailsUrl,
       );
     }
   }