Go File Upload

Package Mainimport ("FMT"    "io"    "Io/ioutil"    "Log"    "net/http"    "OS"    "reflect")Const(Upload_dir="./uploads") Func Uploadhandler (w http. Responsewriter, R*http. Request) {ifR.method = ="GET"{io. WriteString (W," ""+"enctype=\ "Multipart/form-data\" >"+"Choose an image to upload: <input name=\ "image\" type=\ "file\"/>"+"<input type=\ "submit\" value=\ "upload\"/>"+"</form>")        return    }    ifR.method = ="POST"{F, H, err:= R.formfile ("Image")        ifErr! =Nil {http. Error (W, err. Error (), HTTP. Statusinternalservererror)return} filename:=H.filename FMT. Println ("FileName:", filename) defer f.close ()//file stream handleT, err:= OS. Create (Upload_dir +"/"+filename) fmt. Println ("filepath:", upload_dir+"/"+filename)ifErr! =Nil {http. Error (W, err. Error (), HTTP. Statusinternalservererror)return} defer t.close ()//Close the temp file handle        if_, Err: = Io. Copy (T, f); Err! =Nil {http. Error (W, err. Error (), HTTP. Statusinternalservererror)return} http. Redirect (W, R,"/view?id="+filename, http. Statusfound)}}func Viewhandler (w http. Responsewriter, R*http. Request) {imageId:= R.formvalue ("ID") ImagePath:= Upload_dir +"/"+imageIdifexists: = Isexists (ImagePath);!exists {http. NotFound (W, R)return} w.header (). Set ("Content-type","Image")//HTTP response header output formathttp. Servefile (W, R, ImagePath)}func isexists (Pathstring)BOOL{_, Err:=OS. Stat (PATH)ifErr = =Nil {return true    }    returnOS. Isexist (Err)}func Listhandler (w http. Responsewriter, R*http. Request) {Fileinfoarr, err:= Ioutil. ReadDir ("./uploads")    ifErr! =Nil {http. Error (W, err. Error (), HTTP. Statusinternalservererror)return    }    varListhtmlstring     for_, FileInfo: =range Fileinfoarr {imgid:=Fileinfo.name FMT. Println ("Type:", reflect. TypeOf (Imgid)) listhtml+="<li><a href=\ "/view?id="+ imgid () +"\ ">"+ imgid () +"</a></li>"} io. WriteString (W,""+listhtml+"</ol></body>")}func init () {//main function before executingFmt. Println ("init-----")}func Safehandler (fn http. Handlerfunc) http. Handlerfunc {//Handling of exceptions    returnFunc (w http. Responsewriter, R *http. Request) {defer func () {ifE, OK: =recover (). (error); OK {http. Error (W, err. Error (), HTTP. Statusinternalservererror) log. Println ("warn:panic in%v-%v", FN, e) log. Println (string(Debug. Stack ()))}} () fn (W, R) }}//working with Static resourcesFunc Staticdirhandler (Mux *http. Servemux, Prefixstring, Staticdirstring, flagsint) {Mux. Handlefunc (Prefix, func (w http. Responsewriter, R*http. Request) {file:= Staticdir + R.url. Path[len (prefix)-1:]        if(Flags & listdir) = =0 {            ifexists: = isexists (file);!exists {http. NotFound (W, R)return}} http. Servefile (W, R, file)})}func Main () {mux:=http. Newservemux () Staticdirhandler (MUX,"/assets/","./public",0) http. Handlefunc ("/", Safehandler (listhandler)) http. Handlefunc ("/view", Safehandler (viewhandler)) http. Handlefunc ("/upload", Safehandler (Uploadhandler)) Err:= http. Listenandserve (": 8080", nil)ifErr! =Nil {log. Fatal ("Listenandserve:", Err. Error ())}}

Go File Upload