interface Metadata {
    url: string;
    size: number;
    hash: string;
    contentType: string;
    createdAt: number;
    fileUnique?: string;
}
export declare class ImageCache {
    private savePath;
    static instance: ImageCache | null;
    private metadata;
    private metadataFile;
    constructor(savePath: string);
    get(key: string): Buffer;
    set(url: string, buffer: Buffer, contentType: string, hash?: string, fileUnique?: string): void;
    has(key: string): boolean;
    delete(key: string): void;
    clear(): void;
    keys(): string[];
    /**
     * 清理过期缓存
     * @param maxAge 最大缓存时间(毫秒)，默认7天
     */
    cleanExpired(maxAge?: number): number;
    getMetadata(key: string): Metadata | undefined;
}
export {};