Golang如何实现基础的图片上传与处理功能_Golang图片上传处理项目实战

func uploadHandler(w http.ResponseWriter, r *http.Request) {
    if r.Method != "POST" {
        http.Error(w, "仅支持 POST 请求", http.StatusMethodNotAllowed)
        return
    }

    // 解析 multipart 表单，限制大小（如 10MB）
    err := r.ParseMultipartForm(10 << 20)
    if err != nil {
        http.Error(w, "解析表单失败", http.StatusBadRequest)
        return
    }

    file, handler, err := r.FormFile("image")
    if err != nil {
        http.Error(w, "获取文件失败", http.StatusBadRequest)
        return
    }
    defer file.Close()

    // 打印文件信息用于调试
    fmt.Printf("上传文件名: %s, 大小: %d\n", handler.Filename, handler.Size)
}

// 读取前 512 字节用于检测类型
buffer := make([]byte, 512)
_, err := file.Read(buffer)
if err != nil {
    http.Error(w, "读取文件出错", http.StatusInternalServerError)
    return
}

// 还原文件指针位置
file.Seek(0, 0)

// 检测 MIME 类型
mimeType := http.DetectContentType(buffer)
if !strings.HasPrefix(mimeType, "image/") {
    http.Error(w, "仅允许图片文件", http.StatusBadRequest)
    return
}

// 可选：进一步限制为特定格式
if mimeType != "image/jpeg" && mimeType != "image/png" {
    http.Error(w, "仅支持 JPG 或 PNG", http.StatusBadRequest)
    return
}

go get github.com/nfnt/resize

import "github.com/nfnt/resize"

// 解码原始图像
img, _, err := image.Decode(file)
if err != nil {
    http.Error(w, "图片解码失败", http.StatusInternalServerError)
    return
}

// 缩放为 800x600，保持比例可使用 resize.Thumbnail
resized := resize.Resize(800, 600, img, resize.Lanczos3)

// 创建保存文件
out, err := os.Create("uploads/" + handler.Filename)
if err != nil {
    http.Error(w, "创建文件失败", http.StatusInternalServerError)
    return
}
defer out.Close()

// 编码为 JPEG 并压缩（质量 90）
err = jpeg.Encode(out, resized, &jpeg.Options{Quality: 90})
if err != nil {
    http.Error(w, "保存图片失败", http.StatusInternalServerError)
    return
}

filename := fmt.Sprintf("%d_%s", time.Now().Unix(), handler.Filename)
filepath := filepath.Join("uploads", filename)

os.MkdirAll("uploads", os.ModePerm)

response := map[string]string{
    "message": "上传成功",
    "url":     "/static/" + filename,
}
json.NewEncoder(w).Encode(response)

http.Handle("/static/", http.StripPrefix("/static/", http.FileServer(http.Dir("uploads"))))