（三四）HarmonyOS Design 的高级数据管理：状态管理框架与数据持久化 原创

// 定义一个包含状态的组件                @Entry                @Component                struct StateExample {                  @State count: number = 0;                                   build() {                    Column({ space: 50 }) {                      Button(`Count: ${this.count}`)                        .onClick(() => {                          this.count++;                        })                    }                    .width('100%')                  }                }
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// 父组件                @Entry                @Component                struct ParentComponent {                  @State value: number = 0;                                   build() {                    Column({ space: 50 }) {                      Button(`Parent Value: ${this.value}`)                        .onClick(() => {                          this.value++;                        })                      ChildComponent({ linkedValue: $value })                    }                    .width('100%')                  }                }                                 // 子组件                @Component                struct ChildComponent {                  @Link linkedValue: number;                                   build() {                    Button(`Child Value: ${this.linkedValue}`)                      .onClick(() => {                        this.linkedValue++;                      })                  }                }
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// 父组件                @Entry                @Component                struct ProvideParent {                  @Provide sharedValue: number = 0;                                   build() {                    Column({ space: 50 }) {                      Button(`Parent Shared Value: ${this.sharedValue}`)                        .onClick(() => {                          this.sharedValue++;                        })                      ConsumeChild()                    }                    .width('100%')                  }                }                                 // 子组件                @Component                struct ConsumeChild {                  @Consume sharedValue: number;                                   build() {                    Button(`Child Shared Value: ${this.sharedValue}`)                  }                }
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import fs from '@ohos.file.fs';                                 // 写入文件                async function writeToFile(filePath: string, data: string) {                  try {                    const fd = await fs.open(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);                    await fs.write(fd, data);                    await fs.close(fd);                  } catch (e) {                    console.error('Write file error:', e);                  }                }                                 // 读取文件                async function readFromFile(filePath: string) {                  try {                    const fd = await fs.open(filePath, fs.OpenMode.READ_ONLY);                    const buffer = new ArrayBuffer(1024);                    const readLength = await fs.read(fd, buffer);                    await fs.close(fd);                    return new TextDecoder().decode(buffer.slice(0, readLength));                  } catch (e) {                    console.error('Read file error:', e);                    return null;                  }                }
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import rdb from '@ohos.data.rdb';                                 // 创建数据库                const config = {                  name: 'example.db',                  version: 1                };                const rdbStore = await rdb.getRdbStore(config, (rdbStore) => {                  rdbStore.executeSql('CREATE TABLE IF NOT EXISTS Person (id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, age INTEGER)');                });                                 // 插入数据                const valuesBucket = {                  name: 'John',                  age: 30                };                const insertResult = await rdbStore.insert('Person', valuesBucket);                                 // 查询数据                const resultSet = await rdbStore.querySql('SELECT * FROM Person');                while (await resultSet.goToNextRow()) {                  const id = resultSet.getInteger(0);                  const name = resultSet.getString(1);                  const age = resultSet.getInteger(2);                  console.log(`ID: ${id}, Name: ${name}, Age: ${age}`);                }                resultSet.close();
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