Flutter学习记录——29.完整实践——实现一个简易日记本应用

古城微笑少年丶 2023-06-20 15:59 87阅读 0赞

### 文章目录 ###

*  1.知识整理
 *  2.项目实现
 *   *  2.1 效果展示
     *  2.2 项目概览
     *  2.3 代码实现
     *   *  2.3.1 引导页的实现
         *  2.3.2 应用首页
         *  2.3.3 第一个页面
         *  2.3.4 时间工具类
         *  2.3.5 个人中心
         *  2.3.6 数据库操作类
 *  3.完整项目

# 1.知识整理 #

本篇练习看似简单，但是已经将应用编写的大部分需要用的功能都贯穿起来进行了实践、并提供了比较好的解决方案，将开发中可能会遇到的很多问题和难点进行了一一解决。

在进行综合实践编写前，我们先整理下我们这节课里用到的一些知识点：

*  引导页（PageView）
 *  顶部 ToolBar（AppBar）
 *  列表（CustomScrollView）
 *  日历（三方库：fluttercustomcalendar）
 *  权重（Flexible、Expanded）
 *  导航组件（CupertinoTabBar）
 *  弹窗（BottomSheet、SnackBar）
 *  输入框（TextField）
 *  通信（EventBut）
 *  路由
 *  下拉刷新（RefreshIndicator）
 *  数据库（官方库：sqflite）
 *  时间格式化
 *  生命周期监听
 *  返回键拦截
 *  List 的操作
 *  复杂布局实现
 *  其他

那么我们这节综合实践课，就通过以上我们学过的一些 Widget 和技术进行实现一个完整的日记本应用，过程不复杂，但是可以检验一下我们的开发实战水平。

# 2.项目实现 #

## 2.1 效果展示 ##

本节课将要实现的日记本应用，效果图和功能展示如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5_size_16_color_FFFFFF_t_70]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5_size_16_color_FFFFFF_t_70 1]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5_size_16_color_FFFFFF_t_70 2]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5_size_16_color_FFFFFF_t_70 3]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5_size_16_color_FFFFFF_t_70 4]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5_size_16_color_FFFFFF_t_70 5]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5_size_16_color_FFFFFF_t_70 6]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5_size_16_color_FFFFFF_t_70 7]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5_size_16_color_FFFFFF_t_70 8]  
我们先简单介绍下我们要实现的应用的功能： 日记本有引导页，具备列表显示功能、日记的新建、查看阅读、编辑功能，并加入了搜索功能。日记的数据存储的本地手机数据库内，提供3个页面进行切换。

1.  首先是引导页：引导页作为应用的一个基本的功能，会为大家实现并提供解决方案
2.  应用页面基本框架：包括一个底部导航栏，带三个页面切换，并在切换时保持页面数据状态
3.  日记的增删改查功能：存储在手机自带数据库中。
4.  日记的搜索功能
5.  关于页面
6.  列表时时通知更新功能
7.  复制剪贴板功能等

由于功能比较完善、比较多，所以这里就挑选比较常见和重要的技术点来进行代码讲解。

## 2.2 项目概览 ##

1.  项目的dart代码结构如下：  
    ![在这里插入图片描述][2019121021035491.png]
2.  使用到的第三方库如下：
    
     *  sqflite：数据库操作
     *  path\_provider：目录路径的读取
     *  oktoast：实现 Toast 提示
     *  event\_bus：通信
     *  flutter\_custom\_calendar：日历功能

dependencies:
      flutter:
        sdk: flutter
      sqflite: ^1.1.6+3
      cupertino_icons: ^0.1.2
      path_provider: ^1.1.0
      oktoast: ^2.2.0
      event_bus: ^1.1.0
      flutter_custom_calendar:
        git:
          url: https://github.com/LXD312569496/flutter_custom_calendar.git

## 2.3 代码实现 ##

### 2.3.1 引导页的实现 ###

// 首先我们看下引导页的实现
    // 引导页我们主要使用PageView来实现
    
    import 'package:flutter/material.dart';
    import 'package:oktoast/oktoast.dart';
    import 'ui/Home.dart';
    
    void main() { 
      runApp(MyApp());
      // 透明状态栏
    // if (Platform.isAndroid) { 
    // SystemUiOverlayStyle systemUiOverlayStyle =
    // SystemUiOverlayStyle(statusBarColor: Colors.transparent);
    // SystemChrome.setSystemUIOverlayStyle(systemUiOverlayStyle);
    // }
    }
    
    class MyApp extends StatelessWidget { 
      @override
      Widget build(BuildContext context) { 
          // Toast三方库包裹最外层
        return OKToast(
            child:
            MaterialApp(
              title: '日记本',
              theme: ThemeData(
                primarySwatch: Colors.grey,
              ),
              home: MyHomePage(),
            ),
            backgroundColor: Colors.black54,
            textPadding:
                const EdgeInsets.symmetric(horizontal: 16.0, vertical: 10.0),
            radius: 20.0,
            position: ToastPosition.bottom);
      }
    }
    
    class MyHomePage extends StatefulWidget { 
      @override
      _MyHomePageState createState() => _MyHomePageState();
    }
    
    class _MyHomePageState extends State<MyHomePage> { 
      // 默认选中第一项
      int _selectedIndex = 0;
      var _pageController = new PageController(initialPage: 0);
    
      @override
      void initState() { 
        super.initState();
        _pageController.addListener(() { 
          print(_pageController.position);
        });
      }
    
      @override
      Widget build(BuildContext context) { 
        return Scaffold(
          body: _buildBody(),
        );
      }
      // 构建页面主体
      _buildBody() { 
        //SafeArea包裹，保证不会在刘海屏等屏幕下出现裁剪、适配
        return SafeArea(
            child: Stack(
          children: <Widget>[
              // PageView实现引导页页面切换
            PageView(
              // 监听控制类
              controller: _pageController,
              onPageChanged: _onSelectChanged,
              children: <Widget>[
                  // 引导页第一个页面
                Container(
                  color: Color.fromRGBO(232, 229, 222, 1),
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.center,
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: <Widget>[
                      Text(
                        '每一天都是电影',
                        style: TextStyle(
                            color: Color.fromRGBO(132, 112, 101, 1), fontSize: 22),
                      ),
                      SizedBox(
                        height: 10,
                      ),
                      Text(
                        '记录精彩的生活，让每一天都有所回忆',
                        style: TextStyle(
                            color: Color.fromRGBO(66, 84, 94, 1), fontSize: 20),
                      )
                    ],
                  ),
                ),
                // 引导页第二个页面
                Container(
                  color: Color.fromRGBO(232, 229, 222, 1),
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.center,
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: <Widget>[
                      Text(
                        '简约至尚',
                        style: TextStyle(
                            color: Color.fromRGBO(72, 186, 249, 1), fontSize: 22),
                      ),
                      SizedBox(
                        height: 10,
                      ),
                      Text(
                        '从内到外力求简约、精美、个性......',
                        style: TextStyle(
                            color: Color.fromRGBO(66, 84, 94, 1), fontSize: 20),
                      )
                    ],
                  ),
                ),
                // 引导页第三个页面
                Container(
                  color: Color.fromRGBO(232, 229, 222, 1),
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.center,
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: <Widget>[
                      Text(
                        '此刻，回忆独一无二',
                        style: TextStyle(
                            color: Color.fromRGBO(98, 95, 78, 1), fontSize: 22),
                      ),
                      SizedBox(
                        height: 10,
                      ),
                      InkWell(
                        onTap: () { 
                          toPage();
                        },
                        child: Text(
                          '开始体验之旅>>',
                          style: TextStyle(
                              color: Color.fromRGBO(66, 84, 94, 1), fontSize: 20),
                        ),
                      )
                    ],
                  ),
                ),
              ],
            ),
            // 绘制引导页的三个圆点指示器
            Align(
              alignment: FractionalOffset.bottomCenter,
              child: Row(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  Container(
                      width: 10,
                      height: 10,
                      margin: EdgeInsets.all(10),
                      decoration: BoxDecoration(
                          shape: BoxShape.circle,
                          color: (_selectedIndex == 0)
                              ? Colors.white70
                              : Colors.black12)),
                  Container(
                      width: 10,
                      height: 10,
                      margin: EdgeInsets.all(10),
                      decoration: BoxDecoration(
                          shape: BoxShape.circle,
                          color: (_selectedIndex == 1)
                              ? Colors.white70
                              : Colors.black12)),
                  Container(
                      width: 10,
                      height: 10,
                      margin: EdgeInsets.all(10),
                      decoration: BoxDecoration(
                          shape: BoxShape.circle,
                          color: (_selectedIndex == 2)
                              ? Colors.white70
                              : Colors.black12))
                ],
              ),
            )
          ],
        ));
      }
    
      void _onSelectChanged(int index) { 
        setState(() { 
          _selectedIndex = index;
        });
      }
    
      // 切换
      void setPageViewItemSelect(int indexSelect) { 
        _pageController.animateToPage(indexSelect,
            duration: const Duration(milliseconds: 300), curve: Curves.ease);
      }
    
      toPage() { 
        //跳转并关闭当前页面
        Navigator.pushAndRemoveUntil(
          context,
          MaterialPageRoute(builder: (context) { 
            return HomePage();
          }),
          (route) => route == null,
        );
      }
    }

### 2.3.2 应用首页 ###

import 'package:flutter/cupertino.dart';
    import 'package:flutter/material.dart';
    import 'package:flutter_note/ui/search.dart';
    import 'package:flutter_note/utils/note_db_helper.dart';
    import 'package:flutter_note/utils/tost_utils.dart';
    import 'package:sqflite/sqflite.dart';
    
    import 'calendar.dart';
    import 'center.dart';
    import 'list.dart';
    import 'write.dart';
    import 'package:path/path.dart';
    
    class HomePage extends StatefulWidget { 
      @override
      State<StatefulWidget> createState() { 
        return HomePageState();
      }
    }
    
    class HomePageState extends State<HomePage> { 
      // 默认选中第一项
      int _selectedIndex = 0;
      var _pageController = new PageController(initialPage: 0);
      int last = 0;
      int index = 0;
    
      NoteDbHelper noteDbHelpter;
    
      @override
      void initState() { 
        super.initState();
        noteDbHelpter = NoteDbHelper();
        getDatabasesPath().then((string) { 
          String path = join(string, 'notesDb.db');
          noteDbHelpter.open(path);
        });
        _pageController.addListener(() { });
      }
    
      // 返回键拦截执行方法
      Future<bool> _onWillPop() { 
        int now = DateTime.now().millisecondsSinceEpoch;
        print(now - last);
        if (now - last > 1000) { 
          last = now;
          Toast.show("再按一次返回键退出");
          return Future.value(false); //不退出
        } else { 
          return Future.value(true); //退出
        }
      }
    
      @override
      Widget build(BuildContext context) { 
        // 要用WillPopScope包裹
        return WillPopScope(
            // 编写onWillPop逻辑
            onWillPop: _onWillPop,
            child: Material(
              child: SafeArea(
                  child: Scaffold(
                appBar: PreferredSize(
                    // Offstage来控制AppBar的显示与隐藏
                    child: Offstage(
                      offstage: _selectedIndex == 2 ? true : false,
                      child: AppBar(
                        backgroundColor: Color.fromRGBO(244, 244, 244, 1),
                        title: Text('备忘录'),
                        primary: true,
                        automaticallyImplyLeading: false,
                        actions: <Widget>[
                          IconButton(
                            icon: Icon(Icons.search),
                            tooltip: '搜索',
                            onPressed: () { 
                              Navigator.push(context,
                                  MaterialPageRoute(builder: (context) { 
                                return SearchPage(
                                  noteDbHelpter: noteDbHelpter,
                                );
                              }));
                            },
                          ),
                          IconButton(
                            icon: Icon(Icons.add),
                            tooltip: '写日记',
                            onPressed: () { 
                              Navigator.push(context,
                                  MaterialPageRoute(builder: (context) { 
                                return WritePage(
                                  noteDbHelpter: noteDbHelpter,
                                  id: -1,
                                );
                              }));
                            },
                          ),
                        ],
                      ),
                    ),
                    preferredSize:
                        Size.fromHeight(MediaQuery.of(context).size.height * 0.07)),
                // 绑定数据
                body: SafeArea(
                    child: PageView(
                  // 监听控制类
                  controller: _pageController,
                  onPageChanged: _onItemTapped,
                  physics: NeverScrollableScrollPhysics(),
                  children: <Widget>[
                    // 三个页面已经进行了封装
                    ListPage(
                      noteDbHelpter: noteDbHelpter,
                    ),
                    CalendarPage(noteDbHelpter: noteDbHelpter),
                    CenterPage(noteDbHelpter: noteDbHelpter),
                  ],
                )),
                // 底部导航栏用CupertinoTabBar
                bottomNavigationBar: CupertinoTabBar(
                  // 导航集合
                  items: <BottomNavigationBarItem>[
                    BottomNavigationBarItem(
                        activeIcon: Icon(
                          Icons.event_note,
                          color: Colors.blue[300],
                        ),
                        icon: Icon(Icons.event_note),
                        title: Text('主页')),
                    BottomNavigationBarItem(
                        activeIcon: Icon(
                          Icons.calendar_today,
                          color: Colors.blue[300],
                        ),
                        icon: Icon(Icons.calendar_today),
                        title: Text('日历')),
                    BottomNavigationBarItem(
                        activeIcon: Icon(
                          Icons.person,
                          color: Colors.blue[300],
                        ),
                        icon: Icon(Icons.person),
                        title: Text('个人中心')),
                  ],
                  currentIndex: _selectedIndex,
                  onTap: setPageViewItemSelect,
                ),
              )),
            ));
      }
    
      void _onItemTapped(int index) { 
        setState(() { 
          _selectedIndex = index;
        });
      }
    
      // 底部点击切换
      void setPageViewItemSelect(int indexSelect) { 
        _pageController.animateToPage(indexSelect,
            duration: const Duration(milliseconds: 300), curve: Curves.ease);
      }
    }

### 2.3.3 第一个页面 ###

import 'dart:async';
    
    import 'package:flutter/cupertino.dart';
    import 'package:flutter/material.dart';
    import 'package:flutter/services.dart';
    import 'package:flutter_note/entity/note.dart';
    import 'package:flutter_note/ui/read.dart';
    import 'package:flutter_note/utils/event_bus.dart';
    import 'package:flutter_note/utils/note_db_helper.dart';
    import 'package:flutter_note/utils/time_utils.dart';
    
    class ListPage extends StatefulWidget { 
        // 构造方法传入了全局数据库操作类
      const ListPage({ 
        Key key,
        @required this.noteDbHelpter,
      }) : super(key: key);
    
      final NoteDbHelper noteDbHelpter;
    
      @override
      State<StatefulWidget> createState() { 
        return ListPageState();
      }
    }
    
    // 继承实现了AutomaticKeepAliveClientMixin用来保证切换页面后数据不会丢失销毁
    class ListPageState extends State<ListPage> with AutomaticKeepAliveClientMixin { 
      ScrollController _scrollController =
          ScrollController(initialScrollOffset: 5, keepScrollOffset: true);
      // 记录列表的数量
      int _size = 0;
      // 记录列表的数据
      List<Note> _noteList = List();
      // EventBus通信类
      StreamSubscription subscription;
    
      @override
      void initState() { 
        super.initState();
        // 注册和监听t发送来的UserEven类型事件、数据
        subscription = eventBus.on<NoteEvent>().listen((NoteEvent event) { 
          _onRefresh();
        });
        _scrollController.addListener(() { 
          ///滚动监听
        });
        // 刷新加载数据
        _onRefresh();
      }
    
      @override
      Widget build(BuildContext context) { 
        return Container(
          child: RefreshIndicator(
              child: CustomScrollView(
                shrinkWrap: false,
                primary: false,
                // 回弹效果
                physics: BouncingScrollPhysics(),
                scrollDirection: Axis.vertical,
                controller: _scrollController,
                slivers: <Widget>[
                  SliverToBoxAdapter(
                    child: SizedBox(
                      height: 10,
                    ),
                  ),
                  SliverList(
                    delegate: SliverChildBuilderDelegate(
                        (BuildContext context, int index) { 
                        // 列表的Item布局和数据绑定
                      return InkWell(
                        child:
                            index % 2 == 0 ? getItem(index) : getImageItem(index),
                        onTap: () { 
                          Navigator.push(context,
                              MaterialPageRoute(builder: (context) { 
                            return ReadPage(
                              id: _noteList.elementAt(index).id,
                              noteDbHelpter: widget.noteDbHelpter,
                            );
                          }));
                        },
                        onLongPress: () { 
                          _showBottomSheet(index, context);
                        },
                      );
                    }, childCount: _size),
                  ),
                ],
              ),
              onRefresh: _onRefresh),
        );
      }
        // 长按列表弹窗
      _showBottomSheet(int index, BuildContext c) { 
        showModalBottomSheet(
            context: context,
            builder: (BuildContext context) { 
              return new Column(
                mainAxisSize: MainAxisSize.min,
                children: <Widget>[
                  ListTile(
                    leading: Icon(Icons.content_copy),
                    title: Text("复制"),
                    onTap: () async { 
                      Clipboard.setData(
                          ClipboardData(text: _noteList.elementAt(index).content));
                      Scaffold.of(c).showSnackBar(SnackBar(
                        content: Text("已经复制到剪贴板"),
                        backgroundColor: Colors.black87,
                        duration: Duration(
                          seconds: 2,
                        ),
                      ));
                      Navigator.pop(context);
                    },
                  ),
                  ListTile(
                    leading: Icon(Icons.delete_sweep),
                    title: Text("删除"),
                    onTap: () async { 
                      widget.noteDbHelpter
                          .deleteById(_noteList.elementAt(index).id);
                      setState(() { 
                        _noteList.removeAt(index);
                        _size = _noteList.length;
                      });
                      Navigator.pop(context);
                    },
                  ),
                ],
              );
            });
      }
    
      // 刷新
      Future<Null> _onRefresh() async { 
        await Future.delayed(Duration(seconds: 1), () { 
          print('refresh');
          widget.noteDbHelpter.getDatabase().then((database) { 
            database
                .query('notes', orderBy: 'time DESC')
                .then((List<Map<String, dynamic>> records) { 
              _size = records.length;
              _noteList.clear();
              for (int i = 0; i < records.length; i++) { 
                _noteList.add(Note.fromMap(records.elementAt(i)));
              }
              setState(() { 
                print(_noteList.length);
              });
            });
          });
        });
      }
    
      Widget getItem(int index) { 
        return Container(
          child: Card(
            margin: EdgeInsets.fromLTRB(10, 8, 10, 8),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: <Widget>[
                Row(
                  mainAxisAlignment: MainAxisAlignment.spaceAround,
                  children: <Widget>[
                    Container(
                      padding: EdgeInsets.fromLTRB(20, 10, 20, 5),
                      child: Row(
                        children: <Widget>[
                          Text(
                            '${ DateTime.fromMillisecondsSinceEpoch(_noteList.elementAt(index).time).day}',
                            style: TextStyle(
                                color: Color.fromRGBO(52, 52, 54, 1),
                                fontSize: 50,
                                fontWeight: FontWeight.normal),
                          ),
                          SizedBox(
                            width: 5,
                          ),
                          Column(
                            crossAxisAlignment: CrossAxisAlignment.start,
                            children: <Widget>[
                              Text(
                                '星期${ TimeUtils.getWeekday(DateTime.fromMillisecondsSinceEpoch(_noteList.elementAt(index).time).weekday)}',
                                style: TextStyle(
                                    color: Color.fromRGBO(149, 149, 148, 1),
                                    fontSize: 18),
                              ),
                              Text(
                                TimeUtils.getDate(
                                    DateTime.fromMillisecondsSinceEpoch(
                                        _noteList.elementAt(index).time)),
                                style: TextStyle(
                                    color: Color.fromRGBO(149, 149, 148, 1),
                                    fontSize: 18),
                              ),
                            ],
                          ),
                        ],
                      ),
                    ),
                    Expanded(
                      child: Container(
                        alignment: Alignment.centerRight,
                        padding: EdgeInsets.fromLTRB(0, 5, 20, 5),
                        child: Icon(
                          Icons.wb_sunny,
                          size: 50,
                          color: Color.fromRGBO(252, 205, 24, 1),
                        ),
                      ),
                    ),
                  ],
                ),
                Container(
                  margin: EdgeInsets.all(10),
                  child: Text(
                    _noteList.elementAt(index).content,
                    maxLines: 3,
                    overflow: TextOverflow.ellipsis,
                    style: TextStyle(
                      color: Color.fromRGBO(103, 103, 103, 1),
                      fontSize: 18,
                    ),
                  ),
                ),
              ],
            ),
          ),
        );
      }
    
      Widget getImageItem(int index) { 
        return Container(
          child: Card(
            margin: EdgeInsets.fromLTRB(10, 8, 10, 8),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: <Widget>[
                Row(
                  mainAxisAlignment: MainAxisAlignment.spaceAround,
                  children: <Widget>[
                    Container(
                      padding: EdgeInsets.fromLTRB(20, 10, 20, 5),
                      child: Row(
                        children: <Widget>[
                          Text(
                            _noteList.length == 0
                                ? ''
                                : '${ DateTime.fromMillisecondsSinceEpoch(_noteList.elementAt(index).time).day}',
                            style: TextStyle(
                                color: Color.fromRGBO(52, 52, 54, 1),
                                fontSize: 50,
                                fontWeight: FontWeight.normal),
                          ),
                          SizedBox(
                            width: 5,
                          ),
                          Column(
                            crossAxisAlignment: CrossAxisAlignment.start,
                            children: <Widget>[
                              Text(
                                _noteList.length == 0
                                    ? ''
                                    : '星期${ TimeUtils.getWeekday(DateTime.fromMillisecondsSinceEpoch(_noteList.elementAt(index).time).weekday)}',
                                style: TextStyle(
                                    color: Color.fromRGBO(149, 149, 148, 1),
                                    fontSize: 18),
                              ),
                              Text(
                                _noteList.length == 0
                                    ? ''
                                    : TimeUtils.getDate(
                                        DateTime.fromMillisecondsSinceEpoch(
                                            _noteList.elementAt(index).time)),
                                style: TextStyle(
                                    color: Color.fromRGBO(149, 149, 148, 1),
                                    fontSize: 18),
                              ),
                            ],
                          ),
                        ],
                      ),
                    ),
                    Expanded(
                      child: Container(
                        alignment: Alignment.centerRight,
                        padding: EdgeInsets.fromLTRB(0, 5, 20, 5),
                        child: Icon(
                          Icons.wb_sunny,
                          size: 50,
                          color: Color.fromRGBO(252, 205, 24, 1),
                        ),
                      ),
                    ),
                  ],
                ),
                Container(
                    margin: EdgeInsets.all(10),
                    child: Row(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: <Widget>[
                        ClipRRect(
                          borderRadius: BorderRadius.circular(5.0),
                          child: Image.network(
                            'https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1564678338847&di=ab19cbea9b5d88a9969ce0825ac5c84d&imgtype=0&src=http%3A%2F%2Fattachments.gfan.net.cn%2Fforum%2F201501%2F13%2F143316yttiiyiuvufcoyjh.jpg',
                            height: 108,
                            width: 108,
                            fit: BoxFit.cover,
                          ),
                        ),
                        Expanded(
                            child: Container(
                          padding: EdgeInsets.fromLTRB(10, 0, 0, 0),
                          child: Text(
                            _noteList.elementAt(index).content,
                            maxLines: 4,
                            overflow: TextOverflow.ellipsis,
                            style: TextStyle(
                              color: Color.fromRGBO(103, 103, 103, 1),
                              fontSize: 18,
                            ),
                          ),
                        )),
                      ],
                    )),
              ],
            ),
          ),
        );
      }
    
      @override
      void dispose() { 
        super.dispose();
        subscription.cancel();
      }
        // 保证数据留存
      @override
      bool get wantKeepAlive => true;
    }

里面有一个剪贴板复制的操作：

Clipboard.setData(
                          ClipboardData(text: _noteList.elementAt(index).content));

### 2.3.4 时间工具类 ###

// 主要就是DateTime的一个操作
    
    class TimeUtils { 
      static String getWeekday(int day) { 
        switch (day) { 
          case 1:
            return "一";
          case 2:
            return "二";
          case 3:
            return "三";
          case 4:
            return "四";
          case 5:
            return "五";
          case 6:
            return "六";
          case 7:
            return "日";
        }
      }
    
      static String getDateTime(DateTime dateTime) { 
        return '${ dateTime.year}年${ dateTime.month}月${ dateTime.day}日 ${ dateTime.hour}:${ dateTime.minute}:${ dateTime.second}';
      }
    
      static String getDate(DateTime dateTime) { 
        return '${ dateTime.year}年${ dateTime.month}月';
      }
    }

其他的页面内容大同小异，通知刷新页面使用的是 EventBus，之前的博客有讲解用法，这里就不重复讲解了。

数据库 sqflite 之前也有讲过，这里也不重复讲解了。

### 2.3.5 个人中心 ###

import 'package:flutter/material.dart';
    import 'package:flutter/widgets.dart';
    import 'package:flutter_note/utils/note_db_helper.dart';
    
    import 'about.dart';
    
    class CenterPage extends StatefulWidget { 
      const CenterPage({ 
        Key key,
        @required this.noteDbHelpter,
      }) : super(key: key);
    
      final NoteDbHelper noteDbHelpter;
    
      @override
      State<StatefulWidget> createState() { 
        return CenterPageState();
      }
    }
    
    class CenterPageState extends State<CenterPage>
        with AutomaticKeepAliveClientMixin { 
      @override
      void initState() { 
        super.initState();
      }
    
      @override
      Widget build(BuildContext context) { 
        return Container(
          color: Color.fromRGBO(244, 244, 244, 1),
          padding: EdgeInsets.fromLTRB(10, 0, 10, 0),
          child: Column(
            children: <Widget>[
              SizedBox(
                height: 10,
              ),
              Row(
                children: <Widget>[
                  SizedBox(
                    width: 5,
                  ),
                  Container(
                    decoration:
                        BoxDecoration(shape: BoxShape.circle, color: Colors.white),
                    padding: EdgeInsets.all(3),
                    child: CircleAvatar(
                      backgroundColor: Colors.white,
                      foregroundColor: Colors.blue,
                      backgroundImage: NetworkImage(
                          "https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1564763468169&di=02627b2a0ff227690f3a89c5214bfd86&imgtype=0&src=h"
                          "ttp%3A%2F%2Fpic49.nipic.com%2Ffile%2F20140922%2F2531170_191654419000_2.jpg"),
                      radius: 30.0,
                    ),
                  ),
                  SizedBox(
                    width: 10,
                  ),
                  Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: <Widget>[
                      Text(
                        "最美的日记",
                        style: TextStyle(color: Colors.black, fontSize: 26),
                      ),
                      Text(
                        "编辑资料",
                        style: TextStyle(
                            color: Color.fromRGBO(162, 162, 162, 1), fontSize: 18),
                      )
                    ],
                  )
                ],
              ),
              SizedBox(
                height: 20,
              ),
              Expanded(
                  child: Container(
                child: Column(
                  children: <Widget>[
                    Flexible(
                      child: Row(
                        children: <Widget>[
                          _buildItem(0),
                          _buildItem(1),
                        ],
                      ),
                      flex: 1,
                    ),
                    Flexible(
                      child: Row(
                        children: <Widget>[
                          _buildItem(2),
                          _buildItem(3),
                        ],
                      ),
                      flex: 1,
                    ),
                    Flexible(
                      child: Row(
                        children: <Widget>[
                          _buildItem(4),
                          _buildItem(5),
                        ],
                      ),
                      flex: 1,
                    ),
                  ],
                ),
              )),
              SizedBox(
                height: 10,
              ),
            ],
          ),
        );
      }
    
      _buildItem(int index) { 
        return Expanded(
          child: Container(
            padding: EdgeInsets.fromLTRB(5, 5, 5, 5),
            child: GestureDetector(
              child: Card(
                child: Container(
                  padding: EdgeInsets.all(26),
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: <Widget>[
                      _icons.elementAt(index),
                      Expanded(child: Text("")),
                      _title.elementAt(index),
                      _des.elementAt(index),
                    ],
                  ),
                ),
              ),
              onTap:(){ 
                _click(index);
              },
            ),
          ),
          flex: 1,
        );
      }
    
      void _click(int index) { 
        switch (index) { 
          case 0:
            break;
          case 4:
            Navigator.push(context, MaterialPageRoute(builder: (context) { 
              return AboutPage();
            }));
            break;
        }
      }
    
      List<Icon> _icons = [
        Icon(
          Icons.favorite,
          size: 38,
          color: Colors.yellow,
        ),
        Icon(
          Icons.lock,
          size: 38,
          color: Colors.blue,
        ),
        Icon(
          Icons.feedback,
          size: 38,
          color: Colors.blueAccent,
        ),
        Icon(
          Icons.share,
          size: 38,
          color: Colors.deepPurpleAccent,
        ),
        Icon(
          Icons.error_outline,
          size: 38,
          color: Colors.orange,
        ),
        Icon(
          Icons.settings,
          size: 38,
          color: Colors.red,
        )
      ];
    
      List<Text> _title = [
        Text(
          "我的收藏",
          style: TextStyle(color: Colors.black, fontSize: 20),
        ),
        Text(
          "密码锁",
          style: TextStyle(color: Colors.black, fontSize: 20),
        ),
        Text(
          "吐槽反馈",
          style: TextStyle(color: Colors.black, fontSize: 20),
        ),
        Text(
          "分享",
          style: TextStyle(color: Colors.black, fontSize: 20),
        ),
        Text(
          "关于日记",
          style: TextStyle(color: Colors.black, fontSize: 20),
        ),
        Text(
          "系统设置",
          style: TextStyle(color: Colors.black, fontSize: 20),
        ),
      ];
    
      List<Text> _des = [
        Text(
          "收藏的重要日记",
          style: TextStyle(color: Color.fromRGBO(162, 162, 162, 1), fontSize: 16),
        ),
        Text(
          "设置密码锁",
          style: TextStyle(color: Color.fromRGBO(162, 162, 162, 1), fontSize: 16),
        ),
        Text(
          "吐槽反馈你的想法",
          style: TextStyle(color: Color.fromRGBO(162, 162, 162, 1), fontSize: 16),
        ),
        Text(
          "分享应用给他人",
          style: TextStyle(color: Color.fromRGBO(162, 162, 162, 1), fontSize: 16),
        ),
        Text(
          "版本信息",
          style: TextStyle(color: Color.fromRGBO(162, 162, 162, 1), fontSize: 16),
        ),
        Text(
          "系统相关设置",
          style: TextStyle(color: Color.fromRGBO(162, 162, 162, 1), fontSize: 16),
        ),
      ];
    
      @override
      // TODO: implement wantKeepAlive
      bool get wantKeepAlive => true;
    }

### 2.3.6 数据库操作类 ###

import 'package:flutter_note/entity/note.dart';
    import 'package:sqflite/sqflite.dart';
    
    // 数据库操作工具类
    class NoteDbHelper { 
      Database db;
    
      Future open(String path) async { 
        // 打开/创建数据库
        db = await openDatabase(path, version: 1,
            onCreate: (Database db, int version) async { 
          await db.execute(
              "create table notes (_id INTEGER primary key autoincrement,title TEXT not null,content TEXT not null,star INTEGER not null,time INTEGER not null,weather INTEGER not null)");
          print("Table is created");
        });
      }
    
      Future<Database> getDatabase() async { 
        Database database = await db;
        return database;
      }
    
      // 增加一条数据
      Future<Note> insert(Note note) async { 
        note.id = await db.insert("notes", note.toMap());
        return note;
      }
    
      // 通过ID查询一条数据
      Future<Note> getNoteById(int id) async { 
        List<Map> maps = await db.query('notes',
            columns: [
              columnId,
              columnTitle,
              columnContent,
              columnTime,
              columnStar,
              columnWeather
            ],
            where: '_id = ?',
            whereArgs: [id]);
        if (maps.length > 0) { 
          return Note.fromMap(maps.first);
        }
        return null;
      }
    
      // 通过关键字查询数据
      Future<List<Note>> getNoteByContent(String text) async { 
        List<Note> _noteList = List();
        List<Map> maps = await db.query('notes',
            columns: [
              columnId,
              columnTitle,
              columnContent,
              columnTime,
              columnStar,
              columnWeather
            ],
            where: 'content like ? ORDER BY time ASC',
            whereArgs: ["%" + text + "%"]);
        if (maps.length > 0) { 
          for (int i = 0; i < maps.length; i++) { 
            _noteList.add(Note.fromMap(maps.elementAt(i)));
          }
          return _noteList;
        }
        return null;
      }
    
      // 通过ID删除一条数据
      Future<int> deleteById(int id) async { 
        return await db.delete('notes', where: '_id = ?', whereArgs: [id]);
      }
    
      // 更新数据
      Future<int> update(Note note) async { 
        return await db
            .update('notes', note.toMap(), where: '_id = ?', whereArgs: [note.id]);
      }
    
      // 关闭数据库
      Future close() async => db.close();
    }

# 3.完整项目 #

完整项目可以在 Github 上进行下载编译、查看学习：  
[flutter\_notes][flutter_notes]

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5_size_16_color_FFFFFF_t_70 4]: https://img-blog.csdnimg.cn/20191210210119664.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5_size_16_color_FFFFFF_t_70 5]: https://img-blog.csdnimg.cn/20191210210126880.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5,size_16,color_FFFFFF,t_70
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[2019121021035491.png]: https://img-blog.csdnimg.cn/2019121021035491.png
[flutter_notes]: https://github.com/jaychou2012/flutter_notes