主要实现功能

 

1.多文件拖拽上传

2.显示文件上传进度条

3.上传期间，还可以继续拖拽上传

4.可以支持手动修改上传并发任务数

5.上传失败自动重试，最大重试次数3次

6.上传过程中可以手动取消上传

 本次使用的是element ui ，上传拖拽是通过el-upload实现的。

<el-upload
  :before-upload="beforeUpload"
  action="#"
  class="upload"
  drag
  multiple
>
<el-icon class="el-icon--upload">
  <upload-filled/>
</el-icon>
<div class="el-upload__text">
  拖拽或 <em>点击上传</em>
</div>
<template #tip>
  <div class="el-upload__tip">
	请上传文件，仅支持上传文件，不支持文件夹
  </div>
</template>
</el-upload>

 上传之前，触发 beforeUpload 方法，该方法进行封装调用 

beforeUpload(raw) {
  addUploadFile(raw)
  return false
}

上传初始化逻辑

 初始化进度条等相关数据

export function addUploadFile(raw) {
    const upload = uploadStore()
    const uploadProgress = {
        progress: 0,
        file_id: '',
        file_name: raw.name,
        percent: [],
        speed: '0 MB',
        file_size: raw.size,
        upload_size: 0,
        upload_time: new Date()
    }
    // status上传状态 0 队列，1 上传中，2 上传成功 ， 3 取消上传
    // failTryCount 失败上传次数, 没上传一次，自动减去已，当为0的时候，停止上传
    upload.multiFileList.push({file: raw, progress: uploadProgress, status: 0, failTryCount: 3})
    multiUpload()
}

该代码引用了一个类似vuex的存储库 Pinia

 下面内容通过pinia定义了一个存储,存储有三个字段

uploadStore()

export const uploadStore = defineStore('upload', {
    state: () => ({
        multiFileList: [],
        processNumber: 3,
        promise: []
    })
})

multiUpload()

 文件上传核心内容就是该方法了，主要时过滤上传状态为0，然后批量加入上传队列

export function multiUpload() {
    const upload = uploadStore()
    const readFileList = []
    upload.multiFileList.forEach(res => {
        if (res.status === 0) {
            readFileList.push(res)
        }
    })
    if (readFileList.length > 0) {
        multiRun(upload, readFileList.slice(0, upload.processNumber), uploadAsync)
    }
}

 multiRun()

该方法，就是并发上传核心逻辑，通过Promise进行批量上传 

function multiRun(upload, keyList, func) {
    const processNumber = upload.processNumber
    const promise = upload.promise
    for (let i = 0; i < processNumber - promise.length; i++) {
        promise.push(Promise.resolve())
    }
    let reduceNumber = promise.length - processNumber
    if (reduceNumber > 0) {
        upload.promise = promise.slice(0, reduceNumber)
    }
    for (let j = 0; j < keyList.length; j += processNumber) {
        for (let i = 0; i < processNumber; i++) {
            if (i + j < keyList.length) {
                promise[(j + i) % processNumber] = promise[(j + i) % processNumber].then(() => func(keyList[i + j])).catch(({
                                                                                                                                fileInfo,
                                                                                                                                err
                                                                                                                            }) => {
                    if (fileInfo.status === 3) {
                        console.log(fileInfo.file.name, '取消上传')
                    } else {
                        fileInfo.status = 0
                        fileInfo.failTryCount -= 1
                        if (fileInfo.failTryCount < 1) {
                            ElMessage.error(`${fileInfo.file.name} 超过最大重试次数，停止上传`)
                        } else {
                            ElMessage.error(`${fileInfo.file.name} 上传失败，正在重试`)
                            console.log(fileInfo.file.name, err)
                            multiUpload()
                        }
                    }
                })
            }
        }
    }
}

uploadAsync(fileInfo)

上传文件逻辑，进行文件的上传，进度计算等功能。本功能是模拟上传阿里云盘操作

function uploadAsync(fileInfo) {
    const progress = fileInfo.progress
    const file = fileInfo.file
    return new Promise((resolve, reject) => {
        progress.file_name = file.name
        progress.file_size = file.size
        if (fileInfo.status === 0) {
            fileInfo.status = 1
        } else {
            return resolve()
        }
        progress.progress = 10
        getUploadSid().then(async res => {
            // ElMessage.info(fileName + ' 文件读取中')
            progress.speed = '文件读取中'
            let hash = await PreHash(file, progress)
            let fileHashInfo = {
                sid: res.data.sid,
                file_name: progress.file_name,
                file_size: progress.file_size,
                pre_hash: hash
            }
            progress.progress = 20
            checkPreHash(fileHashInfo).then(async pRes => {
                if (pRes.data.check_status === true) {
                    // 秒传逻辑
                    progress.progress = 30
                    const md5Code = pRes.data.md5_token
                    progress.speed = '文件校验中'
                    // ElMessage.info(fileInfo.file_name + ' 秒传检测中')
                    let hash = await ContentHash(file, md5Code, progress)
                    fileHashInfo.proof_code = hash.proofCode
                    fileHashInfo.content_hash = hash.conHash
                    checkContentHash(fileHashInfo).then(async cRes => {
                        if (cRes.data.check_status === true) {
                            progress.progress = 100
                            progress.upload_size = progress.file_size
                            progress.speed = '秒传成功'
                            // ElMessage.success(fileName + ' 上传成功')
                            fileInfo.status = 2
                            fileInfo.upload_time = new Date()
                            multiUpload()
                            resolve()
                        } else {
                            return await ChunkedUpload(fileInfo, fileHashInfo, cRes.data.upload_extra, cRes.data.part_info_list, () => {
                                fileInfo.status = 2
                                fileInfo.upload_time = new Date()
                                multiUpload()
                                resolve()
                            }, (err) => {
                                reject({fileInfo, err})
                            })
                        }
                    }).catch((err) => {
                        reject({fileInfo, err})
                    })
                } else {
                    return await ChunkedUpload(fileInfo, fileHashInfo, pRes.data.upload_extra, pRes.data.part_info_list, () => {
                        fileInfo.status = 2
                        fileInfo.upload_time = new Date()
                        multiUpload()
                        resolve()
                    }, (err) => {
                        reject({fileInfo, err})
                    })
                }
            }).catch((err) => {
                reject({fileInfo, err})
            })
        }).catch((err) => {
            reject({fileInfo, err})
        })
    })
}

 核心上传大概就是这些逻辑

代码源码：xshare/upload.js at main · nineaiyu/xshare · GitHub