Flutter 借助SearchDelegate实现搜索页面，实现搜索建议、搜索结果，解决IOS拼音问题

搜索界面使用Flutter自带的 SearchDelegate 组件实现，通过魔改实现如下效果：

1. 搜素建议
2. 搜索结果，支持刷新和加载更多
3. IOS中文输入拼音问题

界面预览

拷贝源码

将SearchDelegate的源码拷贝一份，修改内容如下：

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

/// 修改此处为 showMySearch
Future<T?> showMySearch<T>({
  required BuildContext context,
  required MySearchDelegate<T> delegate,
  String? query = '',
  bool useRootNavigator = false,
}) {
  delegate.query = query ?? delegate.query;
  delegate._currentBody = _SearchBody.suggestions;
  return Navigator.of(context, rootNavigator: useRootNavigator)
      .push(_SearchPageRoute<T>(
    delegate: delegate,
  ));
}

/// https://juejin.cn/post/7090374603951833118
abstract class MySearchDelegate<T> {
  MySearchDelegate({
    this.searchFieldLabel,
    this.searchFieldStyle,
    this.searchFieldDecorationTheme,
    this.keyboardType,
    this.textInputAction = TextInputAction.search,
  }) : assert(searchFieldStyle == null || searchFieldDecorationTheme == null);

  Widget buildSuggestions(BuildContext context);

  Widget buildResults(BuildContext context);

  Widget? buildLeading(BuildContext context);

  bool? automaticallyImplyLeading;

  double? leadingWidth;

  List<Widget>? buildActions(BuildContext context);

  PreferredSizeWidget? buildBottom(BuildContext context) => null;

  Widget? buildFlexibleSpace(BuildContext context) => null;

  ThemeData appBarTheme(BuildContext context) {
    final ThemeData theme = Theme.of(context);
    final ColorScheme colorScheme = theme.colorScheme;
    return theme.copyWith(
      appBarTheme: AppBarTheme(
        systemOverlayStyle: colorScheme.brightness == Brightness.dark
            ? SystemUiOverlayStyle.light
            : SystemUiOverlayStyle.dark,
        backgroundColor: colorScheme.brightness == Brightness.dark
            ? Colors.grey[900]
            : Colors.white,
        iconTheme: theme.primaryIconTheme.copyWith(color: Colors.grey),
        titleTextStyle: theme.textTheme.titleLarge,
        toolbarTextStyle: theme.textTheme.bodyMedium,
      ),
      inputDecorationTheme: searchFieldDecorationTheme ??
          InputDecorationTheme(
            hintStyle: searchFieldStyle ?? theme.inputDecorationTheme.hintStyle,
            border: InputBorder.none,
          ),
    );
  }

  String get query => _queryTextController.completeText;

  set query(String value) {
    _queryTextController.completeText = value; // 更新实际搜索内容
    _queryTextController.text = value; // 更新输入框内容
    if (_queryTextController.text.isNotEMPty) {
      _queryTextController.selection = TextSelection.fromPosition(
          TextPosition(offset: _queryTextController.text.length));
    }
  }

  void showResults(BuildContext context) {
    _focusNode?.unfocus();
    _currentBody = _SearchBody.results;
  }

  void showSuggestions(BuildContext context) {
    assert(_focusNode != null,
        '_focusNode must be set by route before showSuggestions is called.');
    _focusNode!.requestFocus();
    _currentBody = _SearchBody.suggestions;
  }

  void close(BuildContext context, T result) {
    _currentBody = null;
    _focusNode?.unfocus();
    Navigator.of(context)
      ..POPUntil((Route<dynamic> route) => route == _route)
      ..pop(result);
  }

  final String? searchFieldLabel;

  final TextStyle? searchFieldStyle;

  final InputDecorationTheme? searchFieldDecorationTheme;

  final TextInputType? keyboardType;

  final TextInputAction textInputAction;

  Animation<double> get transitionAnimation => _proxyAnimation;

  FocusNode? _focusNode;

  final ChinaTextEditController _queryTextController = ChinaTextEditController();

  final ProxyAnimation _proxyAnimation =
      ProxyAnimation(kAlwaysDismissedAnimation);

  final ValueNotifier<_SearchBody?> _currentBodyNotifier =
      ValueNotifier<_SearchBody?>(null);

  _SearchBody? get _currentBody => _currentBodyNotifier.value;
  set _currentBody(_SearchBody? value) {
    _currentBodyNotifier.value = value;
  }

  _SearchPageRoute<T>? _route;

  /// Releases the resources.
  @mustCallSuper
  void dispose() {
    _currentBodyNotifier.dispose();
    _focusNode?.dispose();
    _queryTextController.dispose();
    _proxyAnimation.parent = null;
  }
}

/// search page.
enum _SearchBody {
  suggestions,

  results,
}

class _SearchPageRoute<T> extends PageRoute<T> {
  _SearchPageRoute({
    required this.delegate,
  }) {
    assert(
      delegate._route == null,
      'The ${delegate.runtimeType} instance is currently used by another active '
      'search. Please close that search by calling close() on the MySearchDelegate '
      'before opening another search with the same delegate instance.',
    );
    delegate._route = this;
  }

  final MySearchDelegate<T> delegate;

  @override
  Color? get barrierColor => null;

  @override
  String? get barrierLabel => null;

  @override
  Duration get transitionDuration => const Duration(milliseconds: 300);

  @override
  bool get maintainState => false;

  @override
  Widget buildTransitions(
    BuildContext context,
    Animation<double> animation,
    Animation<double> secondaryAnimation,
    Widget child,
  ) {
    return FadeTransition(
      opacity: animation,
      child: child,
    );
  }

  @override
  Animation<double> createAnimation() {
    final Animation<double> animation = super.createAnimation();
    delegate._proxyAnimation.parent = animation;
    return animation;
  }

  @override
  Widget buildPage(
    BuildContext context,
    Animation<double> animation,
    Animation<double> secondaryAnimation,
  ) {
    return _SearchPage<T>(
      delegate: delegate,
      animation: animation,
    );
  }

  @override
  void didComplete(T? result) {
    super.didComplete(result);
    assert(delegate._route == this);
    delegate._route = null;
    delegate._currentBody = null;
  }
}

class _SearchPage<T> extends StatefulWidget {
  const _SearchPage({
    required this.delegate,
    required this.animation,
  });

  final MySearchDelegate<T> delegate;
  final Animation<double> animation;

  @override
  State<StatefulWidget> createState() => _SearchPageState<T>();
}

class _SearchPageState<T> extends State<_SearchPage<T>> {
  // This node is owned, but not hosted by, the search page. Hosting is done by
  // the text field.
  FocusNode focusNode = FocusNode();

  @override
  void initState() {
    super.initState();
    widget.delegate._queryTextController.addListener(_onQueryChanged);
    widget.animation.addStatusListener(_onAnimationStatusChanged);
    widget.delegate._currentBodyNotifier.addListener(_onSearchBodyChanged);
    focusNode.addListener(_onFocusChanged);
    widget.delegate._focusNode = focusNode;
  }

  @override
  void dispose() {
    super.dispose();
    widget.delegate._queryTextController.removeListener(_onQueryChanged);
    widget.animation.removeStatusListener(_onAnimationStatusChanged);
    widget.delegate._currentBodyNotifier.removeListener(_onSearchBodyChanged);
    widget.delegate._focusNode = null;
    focusNode.dispose();
  }

  void _onAnimationStatusChanged(AnimationStatus status) {
    if (status != AnimationStatus.completed) {
      return;
    }
    widget.animation.removeStatusListener(_onAnimationStatusChanged);
    if (widget.delegate._currentBody == _SearchBody.suggestions) {
      focusNode.requestFocus();
    }
  }

  @override
  void didUpdateWidget(_SearchPage<T> oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (widget.delegate != oldWidget.delegate) {
      oldWidget.delegate._queryTextController.removeListener(_onQueryChanged);
      widget.delegate._queryTextController.addListener(_onQueryChanged);
      oldWidget.delegate._currentBodyNotifier
          .removeListener(_onSearchBodyChanged);
      widget.delegate._currentBodyNotifier.addListener(_onSearchBodyChanged);
      oldWidget.delegate._focusNode = null;
      widget.delegate._focusNode = focusNode;
    }
  }

  void _onFocusChanged() {
    if (focusNode.hasFocus &&
        widget.delegate._currentBody != _SearchBody.suggestions) {
      widget.delegate.showSuggestions(context);
    }
  }

  void _onQueryChanged() {
    setState(() {
      // rebuild ourselves because query changed.
    });
  }

  void _onSearchBodyChanged() {
    setState(() {
      // rebuild ourselves because search body changed.
    });
  }

  @override
  Widget build(BuildContext context) {
    assert(debugCheckHasMaterialLocalizations(context));
    final ThemeData theme = widget.delegate.appBarTheme(context);
    final String searchFieldLabel = widget.delegate.searchFieldLabel ??
        MaterialLocalizations.of(context).searchFieldLabel;
    Widget? body;
    switch (widget.delegate._currentBody) {
      case _SearchBody.suggestions:
        body = keyedSubtree(
          key: const ValueKey<_SearchBody>(_SearchBody.suggestions),
          child: widget.delegate.buildSuggestions(context),
        );
      case _SearchBody.results:
        body = KeyedSubtree(
          key: const ValueKey<_SearchBody>(_SearchBody.results),
          child: widget.delegate.buildResults(context),
        );
      case null:
        break;
    }

    late final String routeName;
    switch (theme.platform) {
      case TargetPlatform.iOS:
      case TargetPlatform.macOS:
        routeName = '';
      case TargetPlatform.android:
      case TargetPlatform.fuchsia:
      case TargetPlatform.linux:
      case TargetPlatform.windows:
        routeName = searchFieldLabel;
    }

    return Semantics(
      explicitChildNodes: true,
      scopesRoute: true,
      namesRoute: true,
      label: routeName,
      child: Theme(
        data: theme,
        child: Scaffold(
          appBar: AppBar(
            leadingWidth: widget.delegate.leadingWidth,
            automaticallyImplyLeading:
                widget.delegate.automaticallyImplyLeading ?? true,
            leading: widget.delegate.buildLeading(context),
            title: TextField(
              controller: widget.delegate._queryTextController,
              focusNode: focusNode,
              style: widget.delegate.searchFieldStyle ??
                  theme.textTheme.titleLarge,
              textInputAction: widget.delegate.textInputAction,
              keyboardType: widget.delegate.keyboardType,
              onSubmitted: (String _) => widget.delegate.showResults(context),
              decoration: InputDecoration(hintText: searchFieldLabel),
            ),
            flexibleSpace: widget.delegate.buildFlexibleSpace(context),
            actions: widget.delegate.buildActions(context),
            bottom: widget.delegate.buildBottom(context),
          ),
          body: AnimatedSwitcher(
            duration: const Duration(milliseconds: 300),
            child: body,
          ),
        ),
      ),
    );
  }
}

class ChinaTextEditController extends TextEditingController {
  ///拼音输入完成后的文字
  var completeText = '';

  @override
  TextSpan buildTextSpan(
      {required BuildContext context,
      TextStyle? style,
      required bool withComposing}) {
    ///拼音输入完成
    if (!value.composing.isValid || !withComposing) {
      if (completeText != value.text) {
        completeText = value.text;
        WidgetsBinding.instance.addPostFrameCallback((_) {
          notifyListeners();
        });
      }
      return TextSpan(style: style, text: text);
    }

    ///返回输入样式，可自定义样式
    final TextStyle composingStyle = style?.merge(
      const TextStyle(decoration: TextDecoration.underline),
    ) ?? const TextStyle(decoration: TextDecoration.underline);
    return TextSpan(style: style, children: <TextSpan>[
      TextSpan(text: value.composing.textBefore(value.text)),
      TextSpan(
        style: composingStyle,
        text: value.composing.isValid && !value.composing.isCollapsed
            ? value.composing.textInside(value.text)
            : "",
      ),
      TextSpan(text: value.composing.textAfter(value.text)),
    ]);
  }
}

实现搜索

创建SearchPage继承MySearchDelegate，修改样式，实现页面。需要重写下面5个方法

• appBarTheme：修改搜索样式
• buildActions：搜索框右侧的方法
• buildLeading：搜索框左侧的返回按钮
• buildResults：搜索结果
• buildSuggestions：搜索建议

import 'package:e_book_clone/pages/search/MySearchDelegate.dart';
import 'package:flutter/src/material/theme_data.dart';
import 'package:flutter/src/widgets/framework.dart';

class Demo extends MySearchDelegate {

  @override
  ThemeData appBarTheme(BuildContext context) {
    // TODO: implement appBarTheme
    return super.appBarTheme(context);
  }
  
  @override
  List<Widget>? buildActions(BuildContext context) {
    // TODO: implement buildActions
    throw UnimplementedError();
  }

  @override
  Widget? buildLeading(BuildContext context) {
    // TODO: implement buildLeading
    throw UnimplementedError();
  }

  @override
  Widget buildResults(BuildContext context) {
    // TODO: implement buildResults
    throw UnimplementedError();
  }

  @override
  Widget buildSuggestions(BuildContext context) {
    // TODO: implement buildSuggestions
    throw UnimplementedError();
  }
}

修改样式

@override
ThemeData appBarTheme(BuildContext context) {
  final ThemeData theme = Theme.of(context);
  final ColorScheme colorScheme = theme.colorScheme;
  return theme.copyWith( // 使用copyWith，适配全局主题
    appBarTheme: AppBarTheme( // AppBar样式修改
      systemOverlayStyle: colorScheme.brightness == Brightness.dark
          ? SystemUiOverlayStyle.light
          : SystemUiOverlayStyle.dark,
      surfaceTintColor: Theme.of(context).colorScheme.surface,
      titleSpacing: 0, // textfield前面的间距
      elevation: 0, // 阴影
    ),
    inputDecorationTheme: InputDecorationTheme(
      isCollapsed: true,
      hintStyle: TextStyle( // 提示文字颜色
          color: Theme.of(ToastUtils.context).colorScheme.inversePrimary),
      filled: true,  // 填充颜色
      contentPadding: EdgeInsets.symmetric(vertical: 10.h, horizontal: 15.w),
      fillColor: Theme.of(context).colorScheme.secondary, // 填充颜色，需要配合 filled
      enabledBorder: OutlineInputBorder( // testified 边框
        borderRadius: BorderRadius.circular(12.r),
        borderSide: BorderSide(
          color: Theme.of(context).colorScheme.surface,
        ),
      ),
      focusedBorder: OutlineInputBorder( // testified 边框
        borderRadius: BorderRadius.circular(12.r),
        borderSide: BorderSide(
          color: Theme.of(context).colorScheme.surface,
        ),
      ),
    ),
  );
}

@override
TextStyle? get searchFieldStyle => TextStyle(fontSize: 14.sp); // 字体大小设置，主要是覆盖默认样式

按钮功能

左侧返回按钮，右侧就放了一个搜索文本，点击之后显示搜索结果

@override
Widget? buildLeading(BuildContext context) {
  return IconButton(
    onPressed: () {
      close(context, null);
    },
    icon: Icon(
      color: Theme.of(context).colorScheme.onSurface,
      Icons.arrow_back_ios_new,
      size: 20.r,
    ),
  );
}

@override
List<Widget>? buildActions(BuildContext context) {
  return [
    Padding(
      padding: EdgeInsets.only(right: 15.w, left: 15.w),
      child: GestureDetector(
        onTap: () {
          showResults(context);
        },
        child: Text(
          '搜索',
          style: TextStyle(
              color: Theme.of(context).colorScheme.primary, fontSize: 15.sp),
        ),
      ),
    )
  ];
}

搜索建议

当 TextField 输入变化时，就会调用 buildSuggestions 方法，刷新布局，因此考虑使用FlutterBuilder管理页面和数据。

final SearchViewModel _viewModel = SearchViewModel();

@override
Widget buildSuggestions(BuildContext context) {
  if (query.isEmpty) {
    // 这里可以展示热门搜索等，有搜索建议时，热门搜索会被替换成搜索建议
    return const SizedBox();
  }
  return FutureBuilder(
    future: _viewModel.getSuggest(query),
    builder: (BuildContext context, AsyncSnapshot<List<Suggest>> snapshot) {
      if (snapshot.connectionState == ConnectionState.waiting) {
        // 数据加载中
        return const Center(child: CircularProgressIndicator());
      } else if (snapshot.hasError) {
        // 数据加载错误
        return Center(child: Text('Error: ${snapshot.error}'));
      } else if (snapshot.hasData) {
        // 数据加载成功，展示结果
        final List<Suggest> searchResults = snapshot.data ?? [];
        return ListView.builder(
            padding: EdgeInsets.all(15.r),
            itemCount: searchResults.length,
            itemBuilder: (context, index) {
              return GestureDetector(
                onTap: () {
                  // 更新输入框
                  query = searchResults[index].text ?? query;
                  showResults(context);
                },
                child: Container(
                  padding: EdgeInsets.symmetric(vertical: 10.h),
                  decoration: BoxDecoration(
                    border: BorderDirectional(
                      bottom: BorderSide(
                        width: 0.6,
                        color: Theme.of(context).colorScheme.surfaceContainer,
                      ),
                    ),
                  ),
                  child: Text('${searchResults[index].text}'),
                ),
              );
            });
      } else {
        // 数据为空
        return const Center(child: Text('No results found'));
      }
    },
  );
}

实体类代码如下：

class Suggest {
  Suggest({
    this.id,
    this.url,
    this.text,
    this.isHot,
    this.hotLevel,
  });

  Suggest.fromJson(dynamic json) {
    id = json['id'];
    url = json['url'];
    text = json['text'];
    isHot = json['is_hot'];
    hotLevel = json['hot_level'];
  }

  String? id;
  String? url;
  String? text;
  bool? isHot;
  int? hotLevel;
}

ViewModel代码如下：

class SearchViewModel {
  Future<List<Suggest>> getSuggest(String keyword) async {
    if (keyword.isEmpty) {
      return [];
    }
    return await JsonApi.instance().fetchSuggestV3(keyword);
  }
}

搜索结果

我们需要搜索结果页面支持 加载更多 ，这里用到了 SmartRefrsh 组件

flutter pub add pull_to_refresh

buildResults方法是通过调用 showResults(context); 方法刷新页面，因此为了方便数据动态变化，新建 search_result_page.dart 页面

import 'package:e_book_clone/comPONEnts/book_tile/book_tile_vertical/my_book_tile_vertical_item.dart';
import 'package:e_book_clone/components/book_tile/book_tile_vertical/my_book_tile_vertical_item_skeleton.dart';
import 'package:e_book_clone/components/my_smart_refresh.dart';
import 'package:e_book_clone/models/book.dart';
import 'package:e_book_clone/models/types.dart';
import 'package:e_book_clone/pages/search/search_vm.dart';
import 'package:e_book_clone/utils/navigator_utils.dart';
import 'package:flutter/material.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';
import 'package:provider/provider.dart';
import 'package:pull_to_refresh/pull_to_refresh.dart';

class SearchResultPage extends StatefulWidget {
  final String query; // 请求参数
  const SearchResultPage({super.key, required this.query});

  @override
  State<SearchResultPage> createState() => _SearchResultPageState();
}

class _SearchResultPageState extends State<SearchResultPage> {
  final RefreshController _refreshController = RefreshController();
  final SearchViewModel _viewModel = SearchViewModel();
  void loadOrRefresh(bool loadMore) {
    _viewModel.getResults(widget.query, loadMore).then((_) {
      if (loadMore) {
        _refreshController.loadComplete();
      } else {
        _refreshController.refreshCompleted();
      }
    });
  }

  @override
  void initState() {
    super.initState();
    loadOrRefresh(false);
  }

  @override
  void dispose() {
    _viewModel.isDispose = true;
    _refreshController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider<SearchViewModel>.value(
      value:  _viewModel,
      builder: (context, child) {
        return Consumer<SearchViewModel>(
          builder: (context, vm, child) {
            List<Book>? searchResult = vm.searchResult;
            // 下拉刷新和上拉加载组件
            return MySmartRefresh(
              enablePullDown: false,
              onl oading: () {
                loadOrRefresh(true);
              },
              controller: _refreshController,
              child: ListView.builder(
                padding: EdgeInsets.only(left: 15.w, right: 15.w, top: 15.h),
                itemCount: searchResult?.length ?? 10,
                itemBuilder: (context, index) {
                  if (searchResult == null) {
                    // 骨架屏 
                    return MyBookTileVerticalItemSkeleton(
                        width: 80.w, height: 120.h);
                  }
                  // 结果渲染组件
                  return MyBookTileVerticalItem(
                    book: searchResult[index],
                    width: 80.w,
                    height: 120.h,
                    onTap: (id) {
                      NavigatorUtils.nav2Detail(
                          context, DetailPageType.ebook, searchResult[index]);
                    },
                  );
                },
              ),
            );
          },
        );
      },
    );
  }
}

MySmartRefresh组件代码如下，主要是对SmartRefresher做了进一步的封装

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

class MySmartRefresh extends StatelessWidget {
  // 启用下拉
  final bool? enablePullDown;

  // 启用上拉
  final bool? enablePullUp;

  // 头布局
  final Widget? header;

  // 尾布局
  final Widget? footer;

  // 刷新事件
  final VoidCallback? onRefresh;

  // 加载事件
  final VoidCallback? onl oading;

  // 刷新组件控制器
  final RefreshController controller;

  final ScrollController? scrollController;

  // 被刷新的子组件
  final Widget child;

  const MySmartRefresh({
    super.key,
    this.enablePullDown,
    this.enablePullUp,
    this.header,
    this.footer,
    this.onLoading,
    this.onRefresh,
    required this.controller,
    required this.child,
    this.scrollController,
  });

  @override
  Widget build(BuildContext context) {
    return _refreshView();
  }

  Widget _refreshView() {
    return SmartRefresher(
      scrollController: scrollController,
      controller: controller,
      enablePullDown: enablePullDown ?? true,
      enablePullUp: enablePullUp ?? true,
      header: header ?? const ClassicHeader(),
      footer: footer ?? const ClassicFooter(),
      onRefresh: onRefresh,
      onl oading: onl oading,
      child: child,
    );
  }
}

SearchViewModel 代码如下：

import 'package:e_book_clone/http/spider/json_api.dart';
import 'package:e_book_clone/models/book.dart';
import 'package:e_book_clone/models/query_param.dart';
import 'package:e_book_clone/models/suggest.dart';
import 'package:flutter/material.dart';

class SearchViewModel extends ChangeNotifier {
  int _currPage = 2;
  bool isDispose = false;
  List<Book>? _searchResult;

  List<Book>? get searchResult => _searchResult;

  Future<List<Suggest>> getSuggest(String keyword) async {
    if (keyword.isEmpty) {
      return [];
    }
    return await JsonApi.instance().fetchSuggestV3(keyword);
  }

  Future getResults(String keyword, bool loadMore, {VoidCallback? callback}) async {
    if (loadMore) {
      _currPage++;
    } else {
      _currPage = 1;
      _searchResult?.clear();
    }

    // 请求参数
    SearchParam param = SearchParam(
      page: _currPage,
      rootKind: null,
      q: keyword,
      sort: "defalut",
      query: SearchParam.ebookSearch,
    );
    // 请求结果
    List<Book> res = await JsonApi.instance().fetchEbookSearch(param);
	
    // 加载更多，使用addAll
    if (_searchResult == null) {
      _searchResult = res;
    } else {
      _searchResult!.addAll(res);
    }

    if (res.isEmpty && _currPage > 0) {
      _currPage--;
    }
    // 防止Provider被销毁，数据延迟请求去通知报错
    if (isDispose) return;
    notifyListeners();
  }
}

buildResults方法如下：

@override
Widget buildResults(BuildContext context) {
  if (query.isEmpty) {
    return const SizedBox();
  }
  return SearchResultPage(query: query);
}

显示搜索界面

注意调用的是我们自己拷贝修改的MySearchDelegate中的方法

onTap: () {
  showMySearch(context: context, delegate: SearchPage());
},

更多内容见

• EBook - 电子书城