[feature] Gin enable gzip encoding (#405)

* add gin gzip dependency

* add gzip middleware to router

* go mod tidy

vendor/github.com/gin-contrib/gzip/handler.go

@@ -0,0 +1,84 @@
+package gzip
+
+import (
+	"compress/gzip"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"path/filepath"
+	"strings"
+	"sync"
+
+	"github.com/gin-gonic/gin"
+)
+
+type gzipHandler struct {
+	*Options
+	gzPool sync.Pool
+}
+
+func newGzipHandler(level int, options ...Option) *gzipHandler {
+	handler := &gzipHandler{
+		Options: DefaultOptions,
+		gzPool: sync.Pool{
+			New: func() interface{} {
+				gz, err := gzip.NewWriterLevel(ioutil.Discard, level)
+				if err != nil {
+					panic(err)
+				}
+				return gz
+			},
+		},
+	}
+	for _, setter := range options {
+		setter(handler.Options)
+	}
+	return handler
+}
+
+func (g *gzipHandler) Handle(c *gin.Context) {
+	if fn := g.DecompressFn; fn != nil && c.Request.Header.Get("Content-Encoding") == "gzip" {
+		fn(c)
+	}
+
+	if !g.shouldCompress(c.Request) {
+		return
+	}
+
+	gz := g.gzPool.Get().(*gzip.Writer)
+	defer g.gzPool.Put(gz)
+	defer gz.Reset(ioutil.Discard)
+	gz.Reset(c.Writer)
+
+	c.Header("Content-Encoding", "gzip")
+	c.Header("Vary", "Accept-Encoding")
+	c.Writer = &gzipWriter{c.Writer, gz}
+	defer func() {
+		gz.Close()
+		c.Header("Content-Length", fmt.Sprint(c.Writer.Size()))
+	}()
+	c.Next()
+}
+
+func (g *gzipHandler) shouldCompress(req *http.Request) bool {
+	if !strings.Contains(req.Header.Get("Accept-Encoding"), "gzip") ||
+		strings.Contains(req.Header.Get("Connection"), "Upgrade") ||
+		strings.Contains(req.Header.Get("Accept"), "text/event-stream") {
+
+		return false
+	}
+
+	extension := filepath.Ext(req.URL.Path)
+	if g.ExcludedExtensions.Contains(extension) {
+		return false
+	}
+
+	if g.ExcludedPaths.Contains(req.URL.Path) {
+		return false
+	}
+	if g.ExcludedPathesRegexs.Contains(req.URL.Path) {
+		return false
+	}
+
+	return true
+}