《HarmonyOS Next 开发实战：从零构建响应式 Todo 应用的基石》

@Entry@Componentstruct HelloWorld {  build() {    Text('Hello, HarmonyOS Next!')      .fontSize(24)      .fontWeight(FontWeight.Bold)      .fontColor('#007AFF')  }}

import storage from '@ohos.data.preferences';
async function initPreferences() {  try {    const preferences = await storage.getPreferences(getContext(this), 'appSettings');    await preferences.put('theme', 'dark');    const savedTheme = await preferences.get('theme', 'light');    console.log('Saved theme:', savedTheme);  } catch (error) {    console.error('Error initializing preferences:', error);  }}

import mediaQuery from '@ohos.mediaquery';
@Entry@Componentstruct ResponsiveLayout {  @State isTablet: boolean = false;  @State isLandscape: boolean = false;
  aboutToAppear() {    const tabletListener = mediaQuery.matchMediaSync('(min-width: 600vp)');    const landscapeListener = mediaQuery.matchMediaSync('(orientation: landscape)');
    tabletListener.on('change', (_) => {      this.isTablet = tabletListener.matches;    });
    landscapeListener.on('change', (_) => {      this.isLandscape = landscapeListener.matches;    });  }
  build() {    Column() {      Text('设备类型: ' + (this.isTablet ? '平板' : '手机'))      Text('屏幕方向: ' + (this.isLandscape ? '横屏' : '竖屏'))    }  }}

import window from '@ohos.window';
@Entry@Componentstruct ThemeSwitcher {  @State isDarkMode: boolean = false;
  updateTheme() {    this.isDarkMode = !this.isDarkMode;    this.updateStatusBarColor();  }
  updateStatusBarColor() {    const windowClass = window.getLastWindow(getContext(this));    windowClass.setWindowBackgroundColor(this.isDarkMode ? '#1C1C1E' : '#F2F2F7');  }
  build() {    Column() {      Text('当前主题: ' + (this.isDarkMode ? '深色' : '浅色'))      Button('切换主题')        .onClick(() => this.updateTheme())    }  }}

class TodoItem {  id: number;  text: string;  isCompleted: boolean;  createdAt: Date;
  constructor(text: string) {    this.id = Date.now();    this.text = text;    this.isCompleted = false;    this.createdAt = new Date();  }}
@Entry@Componentstruct TaskManager {  @State todoList: TodoItem[] = [];  @State newTodoText: string = '';
  addTodo() {    if (this.newTodoText.trim() !== '') {      this.todoList.push(new TodoItem(this.newTodoText.trim()));      this.newTodoText = '';    }  }
  toggleTodoComplete(index: number) {    this.todoList[index].isCompleted = !this.todoList[index].isCompleted;  }
  deleteTodo(index: number) {    this.todoList.splice(index, 1);  }
  build() {    Column() {      TextInput({ placeholder: '添加新任务...', text: this.newTodoText })        .onChange((value: string) => { this.newTodoText = value; })        .width('100%')        .margin({ bottom: 16 })
      Button('添加')        .onClick(() => this.addTodo())
      List() {        ForEach(this.todoList, (item: TodoItem, index: number) => {          ListItem() {            Row() {              Checkbox(item.isCompleted)                .onChange((value: boolean) => this.toggleTodoComplete(index))              Text(item.text)            }          }        })      }    }  }}