175.HarmonyOS NEXT系列教程之列表交换组件状态管理机制

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HarmonyOS NEXT系列教程之列表交换组件状态管理机制

效果演示

1. 状态管理架构

1.1 状态定义

// 操作状态枚举
enum OperationStatus {
    IDLE,       // 空闲状态
    PRESSING,   // 长按状态
    MOVING,     // 移动状态
    DROPPING,   // 放置状态
    DELETE      // 删除状态
}

// 组件状态
@Observed
export class ListExchangeCtrl<T> {
    // 列表数据
    private deductionData: Array<T> = [];
    // 当前状态
    state: OperationStatus = OperationStatus.IDLE;
    // 偏移量
    offsetY: number = 0;
}

1.2 状态管理器

class StateManager {
    private static instance: StateManager;
    private currentState: OperationStatus = OperationStatus.IDLE;
    private listeners: Set<(state: OperationStatus) => void> = new Set();

    static getInstance(): StateManager {
        if (!StateManager.instance) {
            StateManager.instance = new StateManager();
        }
        return StateManager.instance;
    }

    setState(newState: OperationStatus): void {
        this.currentState = newState;
        this.notifyListeners();
    }

    private notifyListeners(): void {
        this.listeners.forEach(listener => listener(this.currentState));
    }
}

2. 响应式数据管理

2.1 响应式装饰器

@Observed
export class ListInfo {
    icon: ResourceStr = '';
    name: ResourceStr = '';

    constructor(icon: ResourceStr = '', name: ResourceStr = '') {
        this.icon = icon;
        this.name = name;
    }
}

2.2 状态监听

class StateObserver {
    // 监听状态变化
    static observe(target: any, callback: () => void): void {
        Watch(target)(() => {
            callback();
        })
    }

    // 取消监听
    static unobserve(target: any): void {
        // 取消监听逻辑
    }
}

3. 状态更新机制

3.1 状态更新

class ListExchangeCtrl<T> {
    // 更新状态
    private updateState(newState: OperationStatus): void {
        // 状态转换验证
        if (this.isValidStateTransition(this.state, newState)) {
            this.state = newState;
            this.handleStateChange();
        }
    }

    // 验证状态转换
    private isValidStateTransition(
        currentState: OperationStatus, 
        newState: OperationStatus
    ): boolean {
        // 状态转换验证逻辑
        return true;
    }
}

3.2 批量更新

class BatchUpdater {
    private static updates: Array<() => void> = [];
    private static isProcessing: boolean = false;

    static addUpdate(update: () => void): void {
        this.updates.push(update);
        this.processUpdates();
    }

    private static async processUpdates(): Promise<void> {
        if (this.isProcessing) return;
        this.isProcessing = true;

        while (this.updates.length > 0) {
            const update = this.updates.shift();
            await update();
        }

        this.isProcessing = false;
    }
}

4. 状态同步机制

4.1 UI同步

class UISynchronizer {
    // 同步UI状态
    static syncUI(state: OperationStatus): void {
        switch (state) {
            case OperationStatus.PRESSING:
                this.applyPressingStyle();
                break;
            case OperationStatus.MOVING:
                this.applyMovingStyle();
                break;
            case OperationStatus.DROPPING:
                this.applyDroppingStyle();
                break;
            default:
                this.applyDefaultStyle();
        }
    }

    private static applyPressingStyle(): void {
        // 应用长按状态样式
    }
}

4.2 数据同步

class DataSynchronizer {
    // 同步数据状态
    static syncData(data: Array<any>): void {
        // 数据同步逻辑
    }

    // 处理数据冲突
    static resolveConflict(localData: any, remoteData: any): any {
        // 冲突解决逻辑
        return mergedData;
    }
}

5. 状态持久化

5.1 状态存储

class StatePersistence {
    // 保存状态
    static async saveState(state: any): Promise<void> {
        try {
            await localStorage.setItem('appState', JSON.stringify(state));
        } catch (error) {
            console.error('Failed to save state:', error);
        }
    }

    // 恢复状态
    static async restoreState(): Promise<any> {
        try {
            const state = await localStorage.getItem('appState');
            return JSON.parse(state);
        } catch (error) {
            console.error('Failed to restore state:', error);
            return null;
        }
    }
}

5.2 状态恢复

class StateRecovery {
    // 恢复到上一个状态
    static async recoverToPreviousState(): Promise<void> {
        const previousState = await StatePersistence.restoreState();
        if (previousState) {
            StateManager.getInstance().setState(previousState);
        }
    }
}

6. 性能优化

6.1 状态缓存

class StateCache {
    private static cache: Map<string, any> = new Map();

    static set(key: string, value: any): void {
        this.cache.set(key, value);
    }

    static get(key: string): any {
        return this.cache.get(key);
    }

    static clear(): void {
        this.cache.clear();
    }
}

6.2 更新优化

class UpdateOptimizer {
    private static updateQueue: Array<() => void> = [];
    private static updateScheduled: boolean = false;

    static scheduleUpdate(update: () => void): void {
        this.updateQueue.push(update);
        if (!this.updateScheduled) {
            this.updateScheduled = true;
            requestAnimationFrame(() => this.processUpdates());
        }
    }

    private static processUpdates(): void {
        while (this.updateQueue.length > 0) {
            const update = this.updateQueue.shift();
            update();
        }
        this.updateScheduled = false;
    }
}

7. 最佳实践

7.1 状态管理原则

1. 单一数据源
2. 状态不可变性
3. 单向数据流
4. 响应式更新

7.2 开发建议

1. 合理划分状态
2. 优化更新性能
3. 实现状态回滚
4. 处理异常情况

8. 小结

本篇教程详细介绍了：

1. 状态管理的架构设计
2. 响应式数据的处理方式
3. 状态更新的实现机制
4. 状态同步的处理方法
5. 性能优化的策略

下一篇将介绍列表项操作的实现细节。