图像上传接口自动限制图像大小，缩放

controller/file.go

@@ -12,7 +12,8 @@ import (
 	"log"
 	"net/http"
 	"os"
-	"strings"
+	"github.com/nfnt/resize"
+	"image/jpeg"
 )
 
 type FileController struct {
@@ -30,49 +31,29 @@ func (this *FileController) OnUpload(c *gin.Context) {
 		log.Print(err.Error())
 		return
 	}
-	bytes,err := ioutil.ReadAll(file)
-	if nil != err{
-		log.Print(err.Error())
-		return
+	img, name, err := image.Decode(file)
+	bound := img.Bounds()
+    dx := bound.Dx()
+	dy := bound.Dy()
+	log.Printf("%d %d %s",dx,dy,name)
+    if err != nil {
+        log.Print(err)
 	}
-	header := make([]byte,512)
-	copy(header,bytes)
-	types := http.DetectContentType(header)
-	log.Print(types)
-	// jpg
-	if strings.Contains(types,"jpeg"){
-		defer file.Close()
-		out, err := os.Create("image/" + uid.String() + ".jpg")
+	// resize to width 1000 using Lanczos resampling
+	// and preserve aspect ratio
+	if(dx > 800){
+		dx = dx / 2;
+	}
+	m := resize.Resize(uint(dx), 0, img, resize.Lanczos3)
+
+	datout, err := os.Create("image/" + uid.String() + "." + name)
+	defer datout.Close()
 	if err != nil {
 		log.Fatal(err)
 	}
-		defer out.Close()
-		out.Write(bytes)
-		log.Print(len(bytes))
-		c.JSON(200, map[string] interface{}{"url":uid.String() + ".jpg" })
-	}
-	if strings.Contains(types,"png"){
-		defer file.Close()
-		out, err := os.Create("image/" + uid.String() + ".png")
-		if err != nil {
-			log.Fatal(err)
-		}
-		defer out.Close()
-		out.Write(bytes)
-		log.Print(len(bytes))
-		c.JSON(200, map[string] interface{}{"url":uid.String() + ".png" })
-	}
-	if strings.Contains(types,"gif"){
-		defer file.Close()
-		out, err := os.Create("image/" + uid.String() + ".gif")
-		if err != nil {
-			log.Fatal(err)
-		}
-		defer out.Close()
-		out.Write(bytes)
-		log.Print(len(bytes))
-		c.JSON(200, map[string] interface{}{"url":uid.String() + ".gif" } )
-	}
+	jpeg.Encode(datout, m, nil)
+	c.JSON(200, map[string] interface{}{"url":uid.String() + "." + name } )
+	
 }
 
 func (this *FileController) FileList(c *gin.Context) {