144 lines
6.2 KiB
Swift
144 lines
6.2 KiB
Swift
//
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// MP_CacheManager.swift
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// MusicPlayer
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//
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// Created by Mr.Zhou on 2024/5/23.
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//
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import Foundation
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///缓存实体资源
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class CachedMedia: NSObject, Codable {
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//数据
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let data: Data
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//数据块
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let dataBlocks:[MediaDataBlock]
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//是否完整
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let isComplete: Bool
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//最大长度
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let maxCount:Int64
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init(data: Data, dataBlocks:[MediaDataBlock], isComplete: Bool, maxCount:Int64) {
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self.data = data
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self.dataBlocks = dataBlocks
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self.isComplete = isComplete
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self.maxCount = maxCount
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}
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}
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///缓存管理工具
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class MP_CacheManager {
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// 单例模式，提供全局访问点
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static let shared = MP_CacheManager()
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// 缓存实体，字典形式，键值1为videoID，键值2为对应的资源数据
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private let memoryCache = NSCache<NSString, CachedMedia>()
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//文件管理器
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private let fileManager = FileManager.default
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//缓存文件地址
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private let cacheDirectory: URL
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//缓存专用线程
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private var cacheQueue = DispatchQueue(label: "com.MP_CacheManager.cacheQueue")
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//缓存专用
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private var cacheOperations: [String: DispatchWorkItem] = [:]
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//专用节流时间间隔
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private let throttleInterval: TimeInterval = 1.0
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//固定缓存时间
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private let expirationInterval: TimeInterval = 86400 // 24小时
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private init() {
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//获取全部文件地址
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let urls = fileManager.urls(for: .cachesDirectory, in: .userDomainMask)
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//设置缓存文件地址
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cacheDirectory = urls[0].appendingPathComponent("MyAssetCacheManager")
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//检查缓存文件地址是否存在
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if !fileManager.fileExists(atPath: cacheDirectory.path) {
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//不存在就创建一个
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try? fileManager.createDirectory(at: cacheDirectory, withIntermediateDirectories: true, attributes: nil)
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}
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}
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/// 保存缓存数据
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/// - Parameters:
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/// - data: 数据本身
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/// - key: 使用videoId作为对应的键值
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func cacheData(_ data: Data, dataBlocks:[MediaDataBlock], forKey key: String, isComplete: Bool = false, maxCount:Int64) {
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// 在你的 cacheQueue 里执行操作来确保线程安全
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cacheQueue.async { [weak self] in
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// 取消这个 key 的任何现有缓存操作
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self?.cacheOperations[key]?.cancel()
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// 创建一个新的缓存操作
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let operation = DispatchWorkItem {
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self?.performCacheData(data, dataBlocks: dataBlocks, forKey: key, isComplete: isComplete, maxCount: maxCount)
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// 甚至删除值也包含在cacheQueue的异步调用中
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self?.cacheQueue.async {
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self?.cacheOperations.removeValue(forKey: key)
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}
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}
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// 把 operation 保存进字典
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self?.cacheOperations[key] = operation
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// 安排 operation 在节流间隔后运行
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self?.cacheQueue.asyncAfter(deadline: .now() + self!.throttleInterval, execute: operation)
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}
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}
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//保存缓存数据
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private func performCacheData(_ data: Data, dataBlocks:[MediaDataBlock], forKey key: String, isComplete: Bool = false, maxCount:Int64) {
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let contentToCache = CachedMedia(data: data, dataBlocks: dataBlocks, isComplete: isComplete, maxCount: maxCount)
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memoryCache.setObject(contentToCache, forKey: key as NSString)
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//文件路径
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let fileURL = self.cacheDirectory.appendingPathComponent(key)
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//临时文件
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let tempURL = fileURL.appendingPathExtension("tmp")
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let encoder = JSONEncoder()
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do {
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let newData = try encoder.encode(contentToCache)
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// 写入到文件
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try newData.write(to: tempURL, options: .atomicWrite)
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// 检查目标位置是否已经存在文件，如果存在，则删除
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if self.fileManager.fileExists(atPath: fileURL.path) {
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try self.fileManager.removeItem(at: fileURL)
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}
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// 然后将临时文件移动到最终位置
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try self.fileManager.moveItem(at: tempURL, to: fileURL)
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// 设置过期时间元数据
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let expirationDate = Date().addingTimeInterval(self.expirationInterval)
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try self.fileManager.setAttributes([.modificationDate: expirationDate], ofItemAtPath: fileURL.path)
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} catch {
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// 如果发生错误，删除临时文件
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try? self.fileManager.removeItem(at: tempURL)
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print("无法将密钥数据写入磁盘 \(key) - 错误: \(error)")
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}
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}
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/// 取出数据
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/// - Parameter key: 使用videoId作为对应的键值
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/// - Returns: 返回的数据
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func data(forKey key: String) -> CachedMedia? {
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if let cachedContent = memoryCache.object(forKey: key as NSString){
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return cachedContent
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}
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return cacheQueue.sync {
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[weak self] in
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guard let self = self else { return nil }
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let fileURL = self.cacheDirectory.appendingPathComponent(key)
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guard let jsonData = try? Data(contentsOf: fileURL) else { return nil }
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// 将从磁盘中读取到的 JSON 数据反序列化为 CachedMedia 对象
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let decoder = JSONDecoder()
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do{
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let cachedContent = try decoder.decode(CachedMedia.self, from: jsonData)
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// 检查数据是否过期（同时可以在此处加入完整性检查）
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let attributes = try fileManager.attributesOfItem(atPath: fileURL.path)
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guard let modificationDate = attributes[.modificationDate] as? Date else { return nil }
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if Date().timeIntervalSince(modificationDate) < expirationInterval{
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// 数据未过期，返回数据并更新内存缓存
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memoryCache.setObject(cachedContent, forKey: key as NSString)
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return cachedContent
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} else {
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// 数据已过期，删除缓存文件
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try fileManager.removeItem(at: fileURL)
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}
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} catch {
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print("读取缓存数据失败 \(key) - 错误: \(error)")
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}
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return nil
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}
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}
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}
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