1、指定路徑處理

package main
 
import (
    "bytes"
    "fmt"
    "image"
    "image/jpeg"
    "io/ioutil"
    "math"
    "os"
 
    "code.google.com/p/graphics-go/graphics"
    "github.com/rwcarlsen/goexif/exif"
)
 
// png圖片沒有Orientation信息
func ReadOrientation(filename string) int {
    file, err := os.Open(filename)
    if err != nil {
        fmt.Println("failed to open file, err: ", err)
        return 0
    }
    defer file.Close()
 
    x, err := exif.Decode(file)
    if err != nil {
        fmt.Println("failed to decode file, err: ", err)
        return 0
    }
 
    orientation, err := x.Get(exif.Orientation)
    if err != nil {
        fmt.Println("failed to get orientation, err: ", err)
        return 0
    }
    orientVal, err := orientation.Int(0)
    if err != nil {
        fmt.Println("failed to convert type of orientation, err: ", err)
        return 0
    }
 
    fmt.Println("the value of photo orientation is :", orientVal)
    return orientVal
}
 
func RotateImage(src []byte, angle int) ([]byte, error) {
    var img, _, err = image.Decode(bytes.NewReader(src))
    //var img, err = GetImage(src)
    if err != nil {
        return src, err
    }
    angle = angle % 360
    //弧度轉換
    radian := float64(angle) * math.Pi / 180.0
    cos := math.Cos(float64(radian))
    sin := math.Sin(radian)
    //原圖的寬高
    w := float64(img.Bounds().Dx())
    h := float64(img.Bounds().Dy())
 
    //新圖高寬
    W := int((math.Max(math.Abs(float64(w*cos-h*sin)), math.Abs(w*cos+h*sin))))
    H := int((math.Max(math.Abs(w*sin-h*cos), math.Abs(w*sin+h*cos))))
 
    dst := image.NewNRGBA(image.Rect(0, 0, W, H))
    err = graphics.Rotate(dst, img, &graphics.RotateOptions{radian})
    if err != nil {
        return src, err
    }
 
    file, err := os.Create("newImage.jpg")
    if err != nil {
        return src, err
    }
    defer file.Close()
    err = jpeg.Encode(file, dst, &jpeg.Options{50})
    if err != nil {
        return src, err
    }
 
    return nil, nil
}
 
func main() {
    ori := ReadOrientation("bebRotated.jpg")//先讀取該圖片的原始方向，方向值參考上圖，
    data, err := ioutil.ReadFile("bebRotated.jpg")根據方向值，旋轉圖片
    if err != nil {
        fmt.Println(err)
        return
    }
    fmt.Println(ori)
    //根據圖片原始信息的Orientation判斷需要轉多少度
    if ori == 6 {
        RotateImage(data, 90)
    }
    if ori == 3 {
        RotateImage(data, 180)
    }
    if ori == 8 {
        RotateImage(data, 270)
    }
 
}

2、上傳文件方式處理

package main

import (
    "bytes"
    "fmt"
    "image"
    "image/jpeg"
    "image/png"
    "io/ioutil"
    "mime/multipart"
    "net/http"
    "os"
    "path"
    "strings"
    "testing"

    "github.com/labstack/echo"
)

func uploadImage(c echo.Context) error {
    return createFiles(c, "out/", "/index.html")
}

// createFiles 批量創建文件createFiles(file,"public/crops/","/result_crop")
func createFiles(c echo.Context, savePath, resultUrl string) (err error) {
    savePath = GetPath(savePath)
    var form *multipart.Form
    form, err = c.MultipartForm()
    if err != nil {
        err = c.String(http.StatusOK, fmt.Sprintf("獲取文件失敗，error：%s", err.Error()))
        return
    }

    files := form.File["files"]
    if len(files) <= 0 {
        err = c.String(http.StatusOK, "未上傳任何文件")
        return
    }

    // 清除歷史目錄中的圖片
    var dir []os.FileInfo
    dir, err = ioutil.ReadDir(savePath)
    if err != nil {
        err = c.String(http.StatusOK, fmt.Sprintf("文件名目錄不存在，savePath：%s", savePath))
    }
    for _, d := range dir {
        os.RemoveAll(path.Join([]string{savePath, d.Name()}...))
    }

    // 批量創建文件
    for _, file := range files {
        err = createFile(file, savePath)
        if err != nil {
            return c.String(http.StatusOK, err.Error())
        }
    }
    return c.HTML(http.StatusOK, fmt.Sprintf("<p> successfully </p><script>location.href='%s'</script>", resultUrl))
}

// createFile 創建文件 createFile(file,"public/crops/")
func createFile(file *multipart.FileHeader, savePath string) (err error) {
    var img image.Image
    img, err = getFileImage(file)
    if err != nil {
        return
    }

    // create image file
    out, err := os.Create(savePath + file.Filename)
    if err != nil {
        return err
    }
    defer out.Close()

    // write new image to file
    err = jpeg.Encode(out, img, nil)
    if err != nil {
        return err
    }
    return
}

func getFileImage(file *multipart.FileHeader) (img image.Image, err error) {
    var fileName, ext string
    src, err := file.Open()
    if err != nil {
        err = fmt.Errorf("文件【%s】打開失敗，error：%s", fileName, err.Error())
        return
    }
    defer src.Close()

    fileName = strings.ToLower(file.Filename)
    ext = path.Ext(file.Filename)
    if ext == ".jpg" || ext == ".jpeg" {
        var data []byte
        data, err = ioutil.ReadAll(src)
        if err != nil {
            err = fmt.Errorf("文件【%s】讀取失敗，error：%s", fileName, err.Error())
            return
        }

        // ======= 根據相機圖片原始信息的Orientation判斷需要轉多少度 =======
        // 為什么不直接使用imgFile 而使用 bytes.NewReader(data)，原因：無論image.Decode和image.DecodeConfig消耗從傳入的字節io.Reade，imgFile已在ioutil.ReadAll中消費過，說明：https://stackoverflow.com/questions/62846156/image-decode-unknown-format
        ori := ReadOrientation(bytes.NewReader(data))
        if ori == 6 {
            img, err = RotateImage(bytes.NewReader(data), 90)
        } else if ori == 3 {
            img, err = RotateImage(bytes.NewReader(data), 180)
        } else if ori == 8 {
            img, err = RotateImage(bytes.NewReader(data), 270)
        } else {
            // 非相機照片處理邏輯
            img, err = jpeg.Decode(bytes.NewReader(data))
        }
        if err != nil {
            err = fmt.Errorf("處理文件【%s】失敗，ori：%d，error：%s", fileName, ori, err.Error())
            return
        }
    } else if ext == ".png" {
        img, err = png.Decode(src)
    } else {
        err = fmt.Errorf("文件【%s】格式錯誤，僅支持.jpg、.jpeg、.png格式", fileName)
        return
    }
    if err != nil {
        err = fmt.Errorf(fmt.Sprintf("文件【%s】讀取發送錯誤，error：%s", fileName, err.Error()))
        return
    }
    return
}

func TestImage(t *testing.T) {
    e := echo.New()
    e.POST("/uploadImage", uploadImage)
    e.Logger.Fatal(e.Start(":8081"))
}