Discuss how to transfer files in Golang-Golang-php.cn

Discuss how to transfer files in Golang

PHPz

Release： 2023-04-21 15:00:08

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With the development of the Internet, file transfer has become an indispensable part of modern society. In programming, file transfer is often necessary, especially in network programming. Golang is a concurrent programming language that is efficient to write and easy to maintain, and it also has many solutions for file transfer. In this article, we will explore how to transfer files in Golang.

1. Use the http package to transfer files

In Golang, you can use the http package to quickly and easily implement file transfer. To do this, we need to create an HTTP server that will respond to client requests and send files to the client.

For example, we can create the following server:

package main

import (
    "fmt"
    "net/http"
)

func main() {
    http.HandleFunc("/", func(responseWriter http.ResponseWriter, request *http.Request) {
        http.ServeFile(responseWriter, request, "example.txt")
    })

    err := http.ListenAndServe(":8080", nil)
    if err != nil {
        fmt.Println(err)
    }
}

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The above code creates an HTTP server whose main function is to send a file named "example.txt" as a response to the client end. The http.HandleFunc function is used here, which registers "/" as the path and an anonymous function as the handler function. This anonymous function uses the http.ServeFile function to read and send the file. Finally, print error information when err != nil.

It should be noted that before transferring the file, we need to create a text file named "example.txt" and save it in the server directory.

2. Use TCP to transfer files

In Golang, we can also use TCP protocol to transfer files. This method requires creating a client and server to transfer files between them. Here, we need to use the net package, which provides some utility functions and types for socket-based network programming.

The following is an example of using the TCP protocol to transfer files:

Server:

package main

import (
    "fmt"
    "net"
    "os"
)

func main() {
    // 创建TCP监听器，监听请求
    listener, err := net.Listen("tcp", ":8080")
    if err != nil {
        fmt.Println("Error listening:", err.Error())
        os.Exit(1)
    }
    defer listener.Close()
    fmt.Println("Listening on :8080")

    // 开始监听
    for {
        // 等待客户端连接
        conn, err := listener.Accept()
        if err != nil {
            fmt.Println("Error accepting:", err.Error())
            continue
        }

        // 先读取文件名，再读取文件
        fileName := make([]byte, 64)
        _, err = conn.Read(fileName)
        if err != nil {
            fmt.Println("Error reading filename:", err.Error())
            continue
        }
        file, err := os.Create(string(fileName))
        if file != nil {
            defer file.Close()
        }
        if err != nil {
            fmt.Println("Error create file:", err.Error())
            continue
        }

        // 开始读取文件内容，并写入本地文件
        buf := make([]byte, 1024)
        for {
            n, err := conn.Read(buf)
            if err != nil {
                fmt.Println("Error reading content:", err.Error())
                break
            }
            if n == 0 {
                break
            }
            _, err = file.Write(buf[:n])
            if err != nil {
                fmt.Println("Error writing to file:", err.Error())
                break
            }
        }
        fmt.Printf("Receive file %s success\n", string(fileName))
    }
}

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The above code creates a TCP server, which will Listen to client requests, read the file content through the file name, and save the file in the current directory. Next, we will send a file to this server through the following client program:

Client:

package main

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

func main() {
    // 打开本地文件
    file, err := os.Open("example.txt")
    if err != nil {
        fmt.Println("Error open file:", err.Error())
        os.Exit(1)
    }
    defer file.Close()

    // 连接服务端
    conn, err := net.Dial("tcp", "127.0.0.1:8080")
    if err != nil {
        fmt.Println("Error connect to server:", err.Error())
        os.Exit(1)
    }
    defer conn.Close()

    // 先发送文件名，再发送文件内容
    fileName := "example.txt"
    _, _ = conn.Write([]byte(fileName))
    content, err := ioutil.ReadFile(fileName)
    if err != nil {
        fmt.Println("Error Read file:", err.Error())
        os.Exit(1)
    }

    _, err = conn.Write(content)
    if err != nil {
        fmt.Println("Error send file:", err.Error())
        os.Exit(1)
    }
    fmt.Println("Send success")
}

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The client can send a file named "example. txt" file to the TCP server we created before. The client sends file information to the server by opening a local file and using net.Dial and conn.Write.

Summary:

In Golang, we can use HTTP and TCP protocols to transfer files. The implementation of the HTTP protocol is usually simpler and more convenient, but in some cases it may be more helpful to use the TCP protocol, such as when large files need to be transferred or precise control of file transfers is required. Understanding the pros and cons of both transfer methods and matching them to your needs is crucial to completing a successful file transfer.

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