Golang Web开发中如何处理文件上传 从接收到存储的完整流程

package main

import (
    "fmt"
    "io"
    "net/http"
    "os"
)

func uploadHandler(w http.ResponseWriter, r *http.Request) {
    r.ParseMultipartForm(10 << 20) // 10MB limit
    file, handler, err := r.FormFile("myFile") // "myFile" 是 HTML form 中 file input 的 name
    if err != nil {
        fmt.Println("Error Retrieving the File")
        fmt.Println(err)
        return
    }
    defer file.Close()

    fmt.Printf("Uploaded File: %+v\n", handler.Filename)
    fmt.Printf("File Size: %+v\n", handler.Size)
    fmt.Printf("MIME Header: %+v\n", handler.Header)

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

    // 复制上传的文件到新创建的文件
    if _, err := io.Copy(dst, file); err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    fmt.Fprintf(w, "Successfully Uploaded File\n")
}

func main() {
    http.HandleFunc("/upload", uploadHandler)
    fs := http.FileServer(http.Dir("static"))
    http.Handle("/", fs)
    fmt.Println("Server started on :8080")
    http.ListenAndServe(":8080", nil)
}

// 校验文件类型
buffer := make([]byte, 512)
_, err = file.Read(buffer)
if err != nil {
    http.Error(w, err.Error(), http.StatusInternalServerError)
    return
}

filetype := http.DetectContentType(buffer)
if filetype != "image/jpeg" && filetype != "image/png" {
    http.Error(w, "Invalid file type. Only JPEG or PNG allowed.", http.StatusBadRequest)
    return
}

// 校验文件大小
maxSize := int64(10 * 1024 * 1024) // 10MB
if handler.Size > maxSize {
    http.Error(w, "File size exceeds the limit (10MB).", http.StatusBadRequest)
    return
}

_, err = file.Seek(0, io.SeekStart) // 将文件指针重置到开始位置，以便后续读取
if err != nil {
    http.Error(w, err.Error(), http.StatusInternalServerError)
    return
}

import "github.com/google/uuid"

// 生成唯一文件名
ext := filepath.Ext(handler.Filename)
newFilename := uuid.New().String() + ext
dst, err := os.Create("./uploads/" + newFilename)
if err != nil {
    http.Error(w, err.Error(), http.StatusInternalServerError)
    return
}
defer dst.Close()

// 复制文件内容
if _, err := io.Copy(dst, file); err != nil {
    http.Error(w, err.Error(), http.StatusInternalServerError)
    return
}

package main

import (
    "fmt"
    "io"
    "net/http"
    "os"
)

func uploadHandler(w http.ResponseWriter, r *http.Request) {
    err := r.ParseMultipartForm(10 << 20)
    if err != nil {
        http.Error(w, "Unable to parse form!", http.StatusBadRequest)
        return
    }

    file, handler, err := r.FormFile("file")
    if err != nil {
        http.Error(w, "Error Retrieving the File", http.StatusInternalServerError)
        return
    }
    defer file.Close()

    // 创建目录
    err = os.MkdirAll("./uploads", os.ModeDir|0755)
    if err != nil {
        http.Error(w, "Could not create directory", http.StatusInternalServerError)
        return
    }

    dst, err := os.Create("./uploads/" + handler.Filename)
    if err != nil {
        http.Error(w, "Could not create file", http.StatusInternalServerError)
        return
    }
    defer dst.Close()

    _, err = io.Copy(dst, file)
    if err != nil {
        http.Error(w, "Could not save file", http.StatusInternalServerError)
        return
    }

    fmt.Fprintf(w, "Successfully Uploaded File\n")
}

func main() {
    http.HandleFunc("/upload", uploadHandler)
    fmt.Println("Server started on :8080")
    http.ListenAndServe(":8080", nil)
}