reorganization of _examples and add some new examples such as iris+groupcache+mysql+docker

Former-commit-id: ed635ee95de7160cde11eaabc0c1dcb0e460a620

_examples/file-server/upload-files/main.go

@@ -0,0 +1,116 @@
+package main
+
+import (
+	"crypto/md5"
+	"fmt"
+	"io"
+	"mime/multipart"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/kataras/iris/v12"
+)
+
+func main() {
+	app := newApp()
+	// start the server at http://localhost:8080 with post limit at 32 MB.
+	app.Listen(":8080", iris.WithPostMaxMemory(32<<20 /* same as 32 * iris.MB */))
+}
+
+func newApp() *iris.Application {
+	app := iris.New()
+	app.RegisterView(iris.HTML("./templates", ".html"))
+
+	// Serve the upload_form.html to the client.
+	app.Get("/upload", func(ctx iris.Context) {
+		// create a token (optionally).
+
+		now := time.Now().Unix()
+		h := md5.New()
+		io.WriteString(h, strconv.FormatInt(now, 10))
+		token := fmt.Sprintf("%x", h.Sum(nil))
+
+		// render the form with the token for any use you'd like.
+		ctx.View("upload_form.html", token)
+	})
+
+	// Handle the post request from the upload_form.html to the server.
+	app.Post("/upload", func(ctx iris.Context) {
+		//
+		// UploadFormFiles
+		// uploads any number of incoming files ("multiple" property on the form input).
+		//
+
+		// second argument is optional,
+		// it can be used to change a file's name based on the request,
+		// at this example we will showcase how to use it
+		// by prefixing the uploaded file with the current user's ip.
+		ctx.UploadFormFiles("./uploads", beforeSave)
+	})
+
+	app.Post("/upload_manual", func(ctx iris.Context) {
+		// Get the max post value size passed via iris.WithPostMaxMemory.
+		maxSize := ctx.Application().ConfigurationReadOnly().GetPostMaxMemory()
+
+		err := ctx.Request().ParseMultipartForm(maxSize)
+		if err != nil {
+			ctx.StopWithError(iris.StatusInternalServerError, err)
+			return
+		}
+
+		form := ctx.Request().MultipartForm
+
+		files := form.File["files[]"]
+		failures := 0
+		for _, file := range files {
+			_, err = saveUploadedFile(file, "./uploads")
+			if err != nil {
+				failures++
+				ctx.Writef("failed to upload: %s\n", file.Filename)
+			}
+		}
+		ctx.Writef("%d files uploaded", len(files)-failures)
+	})
+
+	return app
+}
+
+func saveUploadedFile(fh *multipart.FileHeader, destDirectory string) (int64, error) {
+	src, err := fh.Open()
+	if err != nil {
+		return 0, err
+	}
+	defer src.Close()
+
+	out, err := os.OpenFile(filepath.Join(destDirectory, fh.Filename),
+		os.O_WRONLY|os.O_CREATE, os.FileMode(0666))
+	if err != nil {
+		return 0, err
+	}
+	defer out.Close()
+
+	return io.Copy(out, src)
+}
+
+func beforeSave(ctx iris.Context, file *multipart.FileHeader) {
+	ip := ctx.RemoteAddr()
+	// make sure you format the ip in a way
+	// that can be used for a file name (simple case):
+	ip = strings.Replace(ip, ".", "_", -1)
+	ip = strings.Replace(ip, ":", "_", -1)
+
+	// you can use the time.Now, to prefix or suffix the files
+	// based on the current time as well, as an exercise.
+	// i.e unixTime :=	time.Now().Unix()
+	// prefix the Filename with the $IP-
+	// no need for more actions, internal uploader will use this
+	// name to save the file into the "./uploads" folder.
+	if ip == "" {
+		return
+	}
+
+	file.Filename = ip + "-" + file.Filename
+}