How to implement file upload in golang

In recent years, Go language (golang for short) has become more and more popular and concerned by developers due to its efficient concurrency and good performance. In web development, file upload is a common function, so how to use golang to implement file upload? This article will introduce how golang handles file upload operations.

1. Basic principles of file upload

In web development, when the client uploads a file, it first needs to select the file it wants to upload, and then sends the file to the server through the browser. After the server receives the file, it saves the file in the specified folder and saves the file information and other data to the database. In actual operation, the front end often uses ajax or form to implement file upload operations.

2. How to implement file upload in Go language

Golang provides a way to implement file upload. You can directly use the built-in mime/multipart package and process file upload through the multipart.Form object.

The following is a basic file upload code example:

func uploadFile(w http.ResponseWriter, r *http.Request) {
    if r.Method == "POST" {
        err := r.ParseMultipartForm(32 << 20) //用于解析上传文件，mem：32MB
        if err != nil {
            http.Error(w, err.Error(), http.StatusInternalServerError)
            return
        }
        file, handler, err := r.FormFile("inputFile") //获取上传文件
        if err != nil {
            http.Error(w, err.Error(), http.StatusInternalServerError)
            return
        }
        defer file.Close()
        fmt.Fprintf(w, "%v", handler.Header)
        f, err := os.OpenFile("./test/"+handler.Filename, os.O_WRONLY|os.O_CREATE, 0666) //创建文件
        if err != nil {
            http.Error(w, err.Error(), http.StatusInternalServerError)
            return
        }
        defer f.Close()
        io.Copy(f, file) //将上传的文件保存到指定的文件夹中
    } else {
        w.WriteHeader(http.StatusBadRequest)
    }
}

In the above code, when the client sends a POST request and selects file upload, the server will first parse the uploaded file and determine the uploaded file. Whether the file type and size meet the specifications, if so, the file will be saved locally. Among them, the http.MultiPartForm structure is a necessary parameter when uploading files and is used to store specific information about the files.

3. Notes

1. When processing uploaded files, we need to consider whether the file type meets the specifications and whether the size exceeds the limit. In golang, you can use handler.Filename to check the type and size of the file.

2. When processing files, we need to ensure the security of the server. When processing files, we should avoid saving the files in the folder where the program is located, but save them in a special folder, because we often need to clear some junk files in the folder where the program is located, and accidentally delete the uploaded files It will lead to irreversible consequences.

3. In high concurrency situations, we should avoid reading and writing files or database operations as much as possible. At this time, some caching techniques can be used to improve efficiency.

4. Summary

In Web development, file upload is an essential function. In Golang, we can use the mime/multipart package to implement file upload. With this package, we can process uploaded files easily and happily, allowing us to implement Web development more quickly and efficiently.

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