How to use HTTP server function in Go language to download static files?

How to use HTTP server function in Go language to download static files?

When developing web applications, sometimes it is necessary to implement file download functions, such as providing users with the ability to download certain resource files, such as PDF files, pictures, videos, etc. The net/http package in the Go language provides a simple way to implement HTTP server functions and provides the function of downloading files.

Below we will use an example to demonstrate how to use the HTTP server function in the Go language to download static files.

First, we need to import the required package:

package main

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

Next, we need to define a processing function to process user requests and return the contents of the file. We can use the http.ServeContent function to read and send file content.

func downloadHandler(w http.ResponseWriter, r *http.Request) {
    filePath := "./files/sample.txt"

    file, err := os.Open(filePath)
    if err != nil {
        http.Error(w, "File not found.", http.StatusNotFound)
        return
    }
    defer file.Close()

    fileInfo, err := file.Stat()
    if err != nil {
        http.Error(w, "File stat error.", http.StatusInternalServerError)
        return
    }

    http.ServeContent(w, r, fileInfo.Name(), fileInfo.ModTime(), file)
}

In the above code, the downloadHandler function receives two parameters: w http.ResponseWriter and r *http.Request, respectively Used to return responses to the client and receive client request information.

In the function, we first open the file through the os.Open function and check whether an error occurs. If there is an error, a 404 status code is returned to the client.

Next, we obtain the file information, including the file name and modification time, through the file.Stat function.

Finally, we send the file content to the client through the http.ServeContent function. This function receives ResponseWriter, Request, file name, file modification time and file content as parameters, and completes reading and sending the content of the file.

Finally, we need to register the download processing function on the HTTP server and listen to the specified port.

func main() {
    http.HandleFunc("/download", downloadHandler)
    http.ListenAndServe(":8080", nil)
}

In the above code, we use the http.HandleFunc function to register the downloadHandler function as the processing function of the HTTP server. This function receives two parameters: path and processing function.

Finally, we use the http.ListenAndServe function to listen to the specified port. This function receives two parameters: the listening address and the processor.

Finally, we can use the command go run main.go to run the program locally and visit http://localhost:8080/download in the browser , you can download the sample.txt file.

Through the examples in this article, we demonstrate how to use the HTTP server function in the Go language to download static files. We completed the reading and sending of files through the http.ServeContent function, allowing users to easily download the required resource files. At the same time, we also showed how to register the download processing function to the HTTP server and listen to the specified port, thereby realizing a complete download function. Hope this article is helpful to you.

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