Go语言在写HTTP服务程序时，会经常用到文件上传和文件下载，文件上传和文件下载都可以用http包，默认的功能基本上够用了。http包支持文件下载的断点续传和进度显示，文件上传貌似不支持断点续传，不知道是不是要web端来实现。
然后我自己配合web端实现了大文件分片上传，来完成断点续传和进度显示的功能。
基本思想是，在web端将上传的文件进行分片处理，然后向服务端发送上传请求（UploadRequest）包括文件名，MD5，文件大小，和文件总片数。
然后开始一片一片的上传（Upload）。如果暂停了或者断网失败了，就记录当前上传片的片数，下一次上传，重发UploadRequest，chunkPos为续传位置片数，然后从这个记录的片数开始接着上传（Upload）。在服务端，记录首次请求的文件名，MD5，文件大小，文件总片数，然后开始接收每一片，将每一个片保存为一个单独的文件，在接收完最后一个片时，将所有的分片份文件进行合并。保存为对应的文件名。最后再校验MD5码。
对于不同用户的请求，将文件上传的信息存储到session中，当前文件上传暂停后，上传其它文件时，向session增加新文件的信息。暂停后，接着上传最开始的文件，则直接从session中取得该文件的信息，包括文件名，上传到某一个片的信息等。
服务端实现代码：
func UploadRequest(w http.ResponseWriter, r *http.Request) {
log.WithFields(log.Fields{
"HTTP": r.Method,
"FUNC": "UploadRequest",
}).Info("HTTP REQUEST")
header := w.Header()
header.Add("Content-Type", "application/json")
/* session authentication */
sess := session.GlobalSessions.SessionCheck(w, r)
if sess == nil {
log.Error("sess check error")
fmt.Fprintf(w, config.FmtStr, "3000", "error", "session check error")
return
}
defer r.Body.Close()
con, _ := ioutil.ReadAll(r.Body) //获取post的body数据
log.Info("UploadRequest json: ", string(con))
var uploadReq uploadRequest
err := json.Unmarshal([]byte(con), &uploadReq) /* 解析json字符串数据到结构体中 */
if err != nil {
log.Error("json unmarshal error")
fmt.Fprintf(w, config.FmtStr, "2000", "error", "json unmarshal error")
return
}
switch uploadReq.Option {
case "reUploadFile":
{
sess.Set("currentFile", uploadReq)
err := os.Remove("./tmp/" + uploadReq.FileName + "/" + uploadReq.FileName + "_" + uploadReq.ChunkPos)
if err != nil {
log.Error(err)
}
fmt.Fprintf(w, config.FmtStr, "1000", "success", "reupload request success")
}
case "uploadFile":
{
err = os.Mkdir("./tmp/"+uploadReq.FileName, 0777)
if err != nil {
log.Info(err)
fmt.Fprintf(w, config.FmtStr, "3000", "error", "mkdir error")
} else {
log.Infof("create dir %s ok\r\n", uploadReq.FileName)
}
// 文件上传信息保存，保存到session中，用于分片续传时使用
sess.Set(uploadReq.FileName, uploadReq)
sess.Set("currentFile", uploadReq)
fmt.Fprintf(w, config.FmtStr, "1000", "success", "upload request success")
}
case "uploadCancel":
{
err = os.RemoveAll("./tmp/" + uploadReq.FileName)
if err != nil {
log.Fatal(err)
}
sess.Delete(uploadReq.FileName)
fmt.Fprintf(w, config.FmtStr, "1000", "success", "upload file success")
return
}
default:
{
fmt.Fprintf(w, config.FmtStr, "2000", "error", "upload request option error")
}
}
}
/* 分片上传功能实现 */
func Upload(w http.ResponseWriter, r *http.Request) {
log.WithFields(log.Fields{
"HTTP": r.Method,
"FUNC": "Upload",
}).Info("HTTP REQUEST")
header := w.Header()
header.Add("Content-Type", "application/json")
/* session authentication */
sess := globalSessions.SessionCheck(w, r) //session 检查的接口封装
if sess == nil {
log.Error("session check failed")
fmt.Fprintf(w, config.FmtStr, "3000", "error", "session check failed")
return
}
current_dir := sess.Get("current_dir")
log.Info("current dir: ", current_dir)
up_dir := sess.Get("up_dir")
log.Info("up_dir: ", up_dir)
// var current_dir string = "./river/test"
/* 表单上传文件 */
if r.Method == "GET" {
crutime := time.Now().Unix()
h := md5.New()
io.WriteString(h, strconv.FormatInt(crutime, 10))
token := fmt.Sprintf("%x", h.Sum(nil))
t, _ := template.ParseFiles("upload.gtpl")
t.Execute(w, token)
} else {
r.ParseMultipartForm(32 << 20)
file, _, err := r.FormFile("uploadfile")
if err != nil {
log.Error(err)
return
}
defer file.Close()
var uploadFileInfo uploadRequest
uploadFileInfo = sess.Get("currentFile").(uploadRequest)
// fmt.Fprintf(w, "%v", sess.Get("fileName"))
var fileName string = uploadFileInfo.FileName + "_" + uploadFileInfo.ChunkPos
/* 判断上传的文件是否已经存在，可能发生同名的情况 */
log.Debug("fileName: ", fileName)
_, err = os.Stat("./tmp/" + uploadFileInfo.FileName + "/" + fileName)
var f *os.File
if err == nil {
fmt.Fprintf(w, config.FmtStr, "3000", "error", "file is exsited")
return
} else {
f, err = os.OpenFile("./tmp/"+uploadFileInfo.FileName+"/"+fileName, os.O_WRONLY|os.O_CREATE, 0666) // 此处假设当前目录下已存在test目录
}
defer f.Close()
if err != nil {
log.Error(err)
fmt.Fprintf(w, config.FmtStr, "3000", "error", "create file error")
return
}
io.Copy(f, file) //这里进行大文件copy会导致内存占用过大。一段时候后会进行GC回收
log.Info("copy ok")
// 判断是否单个文件是否上传完毕，上传完毕则合并文件到目标文件夹
if uploadFileInfo.ChunkPos == uploadFileInfo.ChunkNum {
f.Close()
_, err = os.Stat(current_dir.(string) + uploadFileInfo.FileName)
var fii *os.File
if err == nil {
// 如果已经存在这个文件了，则在当前文件名后增加日期
time := time.Now().Format("2006-01-02_15-04-05")
log.Debug("Time: ", time)
var fileName []byte = []byte(current_dir.(string) + uploadFileInfo.FileName)
var fileNameFinal []byte = fileName
log.Debug("file_name: ", string(fileName))
var preFileName []byte
var sufFileName []byte
for i := len(fileName) - 1; i > 0; i-- {
if fileName[i] == '.' {
preFileName = fileName[:i] // 文件名前缀 test
sufFileName = fileName[i:] // 文件名后缀 .txt
fileNameFinal = []byte(string(preFileName) + "_" + time + string(sufFileName))
log.Info("fileNameFile: ", fileNameFinal)
break
}
}
fii, err = os.OpenFile(string(fileNameFinal), os.O_WRONLY|os.O_CREATE, 0777) // 此处假设当前目录下已存在test目录
} else {
fii, err = os.OpenFile(current_dir.(string)+uploadFileInfo.FileName, os.O_CREATE|os.O_WRONLY|os.O_APPEND, os.ModePerm)
}
defer fii.Close()
if err != nil {
log.Error(err)
fmt.Fprintf(w, config.FmtStr, "3000", "error", "Open object file error")
return
}
index, _ := strconv.Atoi(uploadFileInfo.ChunkNum)
for i := 1; i <= index; i++ {
f11, err := os.OpenFile("./tmp/"+uploadFileInfo.FileName+"/"+uploadFileInfo.FileName+"_"+strconv.Itoa(int(i)), os.O_RDONLY, os.ModePerm)
if err != nil {
log.Error(err)
fmt.Fprintf(w, config.FmtStr, "3000", "error", "Open slice file error")
return
}
b, err := ioutil.ReadAll(f11)
if err != nil {
log.Error(err)
fmt.Fprintf(w, config.FmtStr, "3000", "error", "ioutil readall error")
return
}
fii.Write(b)
f11.Close()
}
err = os.RemoveAll("./tmp/" + uploadFileInfo.FileName)
if err != nil {
log.Error(err)
}
sess.Delete(uploadFileInfo.FileName)
fii.Close()
if uploadFileInfo.MD5 == FileMD5(fii.Name()) {
err := os.Remove(current_dir.(string) + fii.Name())
if err != nil {
log.Error(err)
}
fmt.Fprintf(w, config.FmtStr, "3000", "error", "upload file md5 error")
} else {
fmt.Fprintf(w, config.FmtStr, "1000", "success", "upload one file all slice success")
}
return
}
chunkPos, err := strconv.Atoi(uploadFileInfo.ChunkPos)
if err != nil {
log.Error(err)
}
uploadFileInfo.ChunkPos = strconv.Itoa(chunkPos + 1)
sess.Set(uploadFileInfo.FileName, uploadFileInfo)
sess.Set("currentFile", uploadFileInfo)
fmt.Fprintf(w, config.FmtStr, "1000", "success", "upload file success")
}
}
func FileMD5(file string) string {
f, err := os.Open(file)
defer f.Close()
if err != nil {
log.Info(err)
return ""
} buffer, _ := ioutil.ReadAll(f)
data := buffer
has := md5.Sum(data)
md5str := fmt.Sprintf("%x", has)
return md5str
}
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