1
class ChatMessage {
2
  final String id;
3
  final String content;
4
  final MessageSender sender;
5
  final DateTime time;
6
  final bool isTyping;
7
  final bool isSelected;
8
  final Map<String, dynamic>? extra;
9

10
  ChatMessage({
11
    required this.id,        // required = 必须传
12
    required this.content,
13
    required this.sender,
14
    required this.time,
15
    this.isTyping = false,   // 有默认值 = 可以不传
16
    this.isSelected = false,
17
    this.extra,              // 可空 = 可以不传
18
  });
19
}

1
class Color {
2
  int r, g, b;
3

4
  Color(this.r, this.g, this.b);
5

6
  // 命名构造函数
7
  Color.red() : r = 255, g = 0, b = 0;
8
  Color.green() : r = 0, g = 255, b = 0;
9
  Color.fromHex(int hex)
10
      : r = (hex >> 16) & 0xFF,
11
        g = (hex >> 8) & 0xFF,
12
        b = hex & 0xFF;
13
}
14

15
var red = Color.red();
16
var custom = Color.fromHex(0xFF5BACF0);

1
class LumiColors {
2
  final Color sidebar;
3
  final Color accent;
4
  // ... 其他 final 字段 ...
5

6
  const LumiColors({       // ← const 构造函数
7
    required this.sidebar,
8
    required this.accent,
9
    // ...
10
  });
11
}
12

13
// 使用 const 创建编译时常量
14
const darkColors = LumiColors(
15
  sidebar: Color(0xFF0E1621),
16
  accent: Color(0xFF5BACF0),
17
);

1
class ChatMessage {
2
  final String id;
3
  final String content;
4
  final MessageSender sender;
5
  final DateTime time;
6
  final bool isTyping;
7
  final bool isSelected;
8
  final Map<String, dynamic>? extra;
9

10
  ChatMessage({
11
    required this.id,
12
    required this.content,
13
    required this.sender,
14
    required this.time,
15
    this.isTyping = false,       // ← 默认值
16
    this.isSelected = false,
17
    this.extra,                  // ← 可空，默认 null
18
  });
19
}

1
class LumiColors extends ThemeExtension<LumiColors> {
2
  final Color sidebar;
3
  final Color bubbleThem;
4
  // ... 9 个 final 字段 ...
5

6
  const LumiColors({              // ← const 构造函数
7
    required this.sidebar,
8
    required this.bubbleThem,
9
    // ...
10
  });
11

12
  factory LumiColors.dark() => const LumiColors(   // ← factory 命名构造
13
    sidebar: Color(0xFF0E1621),
14
    bubbleThem: Color(0xFF182533),
15
    // ...
16
  );
17

18
  factory LumiColors.light() => const LumiColors(  // ← 另一个 factory
19
    sidebar: Color(0xFFFFFFFF),
20
    bubbleThem: Color(0xFFFFFFFF),
21
    // ...
22
  );
23
}

1
class WsService {
2
  // 公开：其他文件可以访问
3
  WsStatus get status => _status;
4
  bool get isAuthenticated => _isAuthenticated;
5

6
  // 私有：只在 ws_service.dart 内可访问
7
  WsStatus _status = WsStatus.disconnected;
8
  bool _isAuthenticated = false;
9
  String? _token;
10
  String _serverUrl = _defaultUrl;
11

12
  void _setStatus(WsStatus s) { /* ... */ }
13
  void _onData(dynamic raw) { /* ... */ }
14
  void _startPing() { /* ... */ }
15
}

1
class AppSettings {
2
  String _fontFamily = 'MiSans';      // 私有字段
3
  bool _closeAstrBotOnExit = false;
4

5
  // 公开 getter：外部可以读
6
  String? get fontFamily => _fontFamily.isEmpty ? null : _fontFamily;
7
  String get fontKey => _fontFamily;
8
  bool get closeAstrBotOnExit => _closeAstrBotOnExit;
9

10
  // 公开方法：外部通过方法修改（可以加校验逻辑）
11
  void setFontFamily(String key) {
12
    if (_fontFamily == key) return;
13
    _fontFamily = key;
14
    notifyListeners();
15
    _save();
16
  }
17
}

1
class Rectangle {
2
  double width;
3
  double height;
4

5
  Rectangle(this.width, this.height);
6

7
  // getter：像访问字段一样使用
8
  double get area => width * height;
9
  double get perimeter => 2 * (width + height);
10
  bool get isSquare => width == height;
11
}
12

13
var rect = Rectangle(10, 20);
14
print(rect.area);       // 200.0 —— 像字段一样访问，但实际是计算出来的
15
print(rect.isSquare);   // false

1
class Temperature {
2
  double _celsius;
3

4
  Temperature(this._celsius);
5

6
  double get celsius => _celsius;
7
  set celsius(double value) {
8
    if (value < -273.15) throw ArgumentError('绝对零度以下');
9
    _celsius = value;
10
  }
11

12
  double get fahrenheit => _celsius * 9 / 5 + 32;
13
  set fahrenheit(double f) => celsius = (f - 32) * 5 / 9;  // 转换后赋值
14
}
15

16
var t = Temperature(100);
17
print(t.fahrenheit);    // 212.0
18
t.fahrenheit = 32;      // setter 自动转换
19
print(t.celsius);       // 0.0

1
class LogEntry {
2
  final DateTime time;
3
  final LogLevel level;
4
  final String message;
5

6
  LogEntry(this.time, this.level, this.message);
7

8
  // getter：格式化时间
9
  String get timeString {
10
    final hh = time.hour.toString().padLeft(2, '0');
11
    final mm = time.minute.toString().padLeft(2, '0');
12
    final ss = time.second.toString().padLeft(2, '0');
13
    return '$hh:$mm:$ss';
14
  }
15

16
  // getter：日志级别转字符串
17
  String get levelString {
18
    switch (level) {
19
      case LogLevel.info: return 'INFO';
20
      case LogLevel.debug: return 'DEBUG';
21
      case LogLevel.warning: return 'WARN';
22
      case LogLevel.error: return 'ERROR';
23
    }
24
  }
25
}

1
class WsService extends ChangeNotifier {
2
  WsStatus _status = WsStatus.disconnected;
3
  WsStatus get status => _status;             // ← 只读 getter
4

5
  bool _isAuthenticated = false;
6
  bool get isAuthenticated => _isAuthenticated;
7

8
  bool _isGenerating = false;
9
  bool get isGenerating => _isGenerating;
10

11
  bool _historyHasMore = true;
12
  bool get hasMoreHistory => _historyHasMore;  // ← getter 名可以和字段名不同
13

14
  final List<ChatMessage> _messages = [];
15
  List<ChatMessage> get messages => List.unmodifiable(_messages);  // ← 返回只读拷贝
16
}

1
class Parent {
2
  String name;
3
  Parent(this.name);
4
  Parent.named(this.name);
5
}
6

7
class Child extends Parent {
8
  int age;
9

10
  // 用法 1：super.field 语法糖（Dart 3）
11
  Child(super.name, this.age);
12

13
  // 用法 2：初始化列表中调用 super()
14
  Child.v2(String name, this.age) : super(name);
15

16
  // 用法 3：调用父类的命名构造函数
17
  Child.v3(String name, this.age) : super.named(name);
18
}

1
mixin Swimmer {
2
  void swim() => print('$runtimeType is swimming');
3
}
4

5
mixin Flyer {
6
  void fly() => print('$runtimeType is flying');
7
}
8

9
// 使用 with 混入
10
class Duck extends Animal with Swimmer, Flyer {
11
  Duck(super.name);
12
}
13

14
var duck = Duck('Donald');
15
duck.swim();  // Duck is swimming
16
duck.fly();   // Duck is flying
17
duck.speak(); // Animal 的方法

1
class _LumiAppState extends State<LumiApp> with WindowListener, TrayListener {
2
//                                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
3
//                   混入窗口事件监听器 和 系统托盘事件监听器
4

5
  @override
6
  void onTrayIconMouseDown() {      // ← 来自 TrayListener
7
    windowManager.show();
8
    windowManager.focus();
9
  }
10

11
  @override
12
  void onTrayMenuItemClick(MenuItem menuItem) async {  // ← 来自 TrayListener
13
    if (menuItem.key == 'show_window') {
14
      await windowManager.show();
15
    } else if (menuItem.key == 'exit_app') {
16
      // ...
17
    }
18
  }
19

20
  @override
21
  Future<void> onWindowClose() async {  // ← 来自 WindowListener
22
    // 窗口关闭时的处理逻辑
23
  }
24
}

1
class Config {
2
  final String host;
3
  final int port;
4
  final bool debug;
5

6
  const Config({
7
    required this.host,
8
    required this.port,
9
    this.debug = false,
10
  });
11

12
  // copyWith：复制自身，只替换指定字段
13
  Config copyWith({
14
    String? host,
15
    int? port,
16
    bool? debug,
17
  }) {
18
    return Config(
19
      host: host ?? this.host,      // 没传就用原值
20
      port: port ?? this.port,
21
      debug: debug ?? this.debug,
22
    );
23
  }
24
}
25

26
var config = Config(host: '127.0.0.1', port: 8765);
27
var newConfig = config.copyWith(port: 9090);
28
// newConfig: host='127.0.0.1', port=9090, debug=false
29
// config 不变（不可变对象）

1
ChatMessage copyWith({
2
  String? content,
3
  bool? isTyping,
4
  bool? isSelected,
5
  Map<String, dynamic>? extra,
6
}) {
7
  return ChatMessage(
8
    id: id,                                 // id 不可改
9
    content: content ?? this.content,       // 没传就用原值
10
    sender: sender,                         // sender 不可改
11
    time: time,                             // time 不可改
12
    isTyping: isTyping ?? this.isTyping,
13
    isSelected: isSelected ?? this.isSelected,
14
    extra: extra ?? this.extra,
15
  );
16
}

1
@override
2
LumiColors copyWith({
3
  Color? sidebar,
4
  Color? bubbleThem,
5
  Color? bubbleMe,
6
  Color? accent,
7
  Color? subtext,
8
  Color? inputBg,
9
  Color? divider,
10
  Color? onBubbleMe,
11
  Color? onBubbleThem,
12
}) {
13
  return LumiColors(
14
    sidebar: sidebar ?? this.sidebar,
15
    bubbleThem: bubbleThem ?? this.bubbleThem,
16
    bubbleMe: bubbleMe ?? this.bubbleMe,
17
    accent: accent ?? this.accent,
18
    subtext: subtext ?? this.subtext,
19
    inputBg: inputBg ?? this.inputBg,
20
    divider: divider ?? this.divider,
21
    onBubbleMe: onBubbleMe ?? this.onBubbleMe,
22
    onBubbleThem: onBubbleThem ?? this.onBubbleThem,
23
  );
24
}

1
class Point {
2
  final double x;
3
  final double y;
4

5
  const Point(this.x, this.y);
6

7
  @override
8
  bool operator ==(Object other) =>
9
      other is Point && other.x == x && other.y == y;
10

11
  @override
12
  int get hashCode => Object.hash(x, y);
13
}
14

15
print(Point(1, 2) == Point(1, 2));  // true（值相等）

1
class Vector {
2
  final double x, y;
3
  const Vector(this.x, this.y);
4

5
  Vector operator +(Vector other) => Vector(x + other.x, y + other.y);
6
  Vector operator -(Vector other) => Vector(x - other.x, y - other.y);
7
  Vector operator *(double scalar) => Vector(x * scalar, y * scalar);
8

9
  @override
10
  String toString() => 'Vector($x, $y)';
11
}
12

13
var v1 = Vector(1, 2);
14
var v2 = Vector(3, 4);
15
print(v1 + v2);     // Vector(4.0, 6.0)
16
print(v1 * 3);      // Vector(3.0, 6.0)