91 lines
2.7 KiB
TypeScript
91 lines
2.7 KiB
TypeScript
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/**
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* 模块：HeadHandler
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* 功能：处理TUS协议的HEAD请求，用于获取上传文件的状态信息
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* 使用场景：在文件分片上传过程中，客户端需要定期查询上传进度时使用
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*/
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import { CancellationContext, ERRORS, Upload, Metadata } from '../utils'
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import { BaseHandler } from './BaseHandler'
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import type http from 'node:http'
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/**
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* HeadHandler类
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* 核心功能：处理TUS协议的HEAD请求，返回文件上传的元数据和进度信息
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* 设计模式：继承自BaseHandler，采用模板方法模式
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* 使用示例：
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* const handler = new HeadHandler(store, options)
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* await handler.send(req, res, context)
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*/
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export class HeadHandler extends BaseHandler {
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/**
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* 处理HEAD请求的核心方法
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* @param req HTTP请求对象
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* @param res HTTP响应对象
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* @param context 取消操作的上下文
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* @returns 返回HTTP响应
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* @throws ERRORS.FILE_NOT_FOUND 文件ID不存在时抛出
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* @throws ERRORS.FILE_NO_LONGER_EXISTS 文件已过期时抛出
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*/
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async send(
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req: http.IncomingMessage,
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res: http.ServerResponse,
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context: CancellationContext
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) {
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// 从请求中提取文件ID
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const id = this.getFileIdFromRequest(req)
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if (!id) {
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throw ERRORS.FILE_NOT_FOUND
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}
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// 执行自定义的请求预处理逻辑
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if (this.options.onIncomingRequest) {
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await this.options.onIncomingRequest(req, res, id)
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}
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// 获取文件锁，防止并发操作
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const lock = await this.acquireLock(req, id, context)
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let file: Upload
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try {
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// 从存储中获取文件上传信息
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file = await this.store.getUpload(id)
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} finally {
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// 无论成功与否，都释放锁
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await lock.unlock()
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}
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// 检查文件是否已过期
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const now = new Date()
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if (
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this.store.hasExtension('expiration') &&
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this.store.getExpiration() > 0 &&
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file.creation_date &&
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now > new Date(new Date(file.creation_date).getTime() + this.store.getExpiration())
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) {
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throw ERRORS.FILE_NO_LONGER_EXISTS
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}
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// 设置响应头，防止缓存
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res.setHeader('Cache-Control', 'no-store')
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// 返回当前上传偏移量
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res.setHeader('Upload-Offset', file.offset)
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// 处理文件大小信息
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if (file.sizeIsDeferred) {
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// 如果文件大小未知，设置延迟长度标志
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res.setHeader('Upload-Defer-Length', '1')
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} else {
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// 如果文件大小已知，返回实际大小
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res.setHeader('Upload-Length', file.size as number)
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}
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// 处理文件元数据
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if (file.metadata !== undefined) {
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// 将元数据转换为字符串格式返回
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res.setHeader('Upload-Metadata', Metadata.stringify(file.metadata) as string)
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}
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// 结束响应
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return res.end()
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}
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}
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