Golang implements network disk

In today's Internet environment, people increasingly need cloud storage services such as network disks. There are currently popular cloud storage services on the market such as Baidu Cloud, Weiyun, Dropbox, etc. However, the privacy and security of these services are not very trusted by people. Therefore, developing a network disk yourself has become an increasingly popular choice.

This article will introduce how to use Golang to develop a web-based network disk service. Golang is an open source programming language developed by Google. It has the characteristics of high concurrency, high performance, simplicity and ease of use. Using Golang to develop network disks can quickly build stable and efficient services.

1. Environment preparation

First, we need to install the Golang environment. After installing Golang, we need to install several necessary libraries:

• gin: a high-performance web framework for Golang, used to quickly build RESTful APIs.
• gorm: Golang's ORM library, used to conveniently operate databases.

After the installation is complete, we can start writing code happily.

2. Use the Gin framework to build a RESTful API

In this project, we use the Gin framework to build a Web service. The Gin framework is simple and easy to use, with almost no learning cost. First create a main.go file and write the following code:

package main

import "github.com/gin-gonic/gin"

func main() {
  // 创建Gin引擎
  r := gin.Default()

  // 路由
  r.GET("/ping", func(c *gin.Context) {
    c.JSON(200, gin.H{
      "message": "pong",
    })
  })

  // 启动服务
  r.Run()
}

This code creates a Gin engine and handles a /ping route. Run the code: go run main.go, then enter http://localhost:8080/ping in the browser, you can see the output: {"message":"pong"}.

3. File Operation

Next we need to upload and download files. Uploading and downloading files requires first connecting to the database, accessing the meta-information of the corresponding file, and then accessing or downloading the file itself.

1. File meta information

We will use MySQL database to store file meta information, including file name, file size, upload time, file storage path on disk, etc. In this project, we use the Gorm library to connect to the MySQL database. Add the following code to main.go:

import (
  "fmt"

  "github.com/jinzhu/gorm"
  _ "github.com/jinzhu/gorm/dialects/mysql"
)

type File struct {
  ID      uint   `gorm:"primary_key"`
  Name    string `gorm:"type:varchar(255)"`
  Size    int64
  Path    string `gorm:"type:varchar(255)"`
  CreatedAt time.Time
}

var db *gorm.DB
var err error

func init() {
  db, err = gorm.Open("mysql", "root:password@/filestore?charset=utf8&parseTime=True&loc=Local")
  if err != nil {
    fmt.Println("连接数据库失败：", err.Error())
    return
  }

  db.AutoMigrate(&File{})
}

The above code creates a File structure, which corresponds to a table in the database. Then use gorm.Open to connect to the MySQL database, and use the AutoMigrate command to automatically create a table named "files" in the database.

2. File upload

In the Gin framework, use the Post method to upload files. We need to add the following code before routing to enable the middleware for uploading files:

r.Static("/static", "./static")
r.POST("/upload", func(c *gin.Context) {
  file, header, err := c.Request.FormFile("file")
  if err != nil {
    c.JSON(http.StatusBadRequest, gin.H{
      "msg": err.Error(),
    })
    return
  }
  defer file.Close()

  // 保存文件到本地
  filename := header.Filename
  filepath := fmt.Sprintf("./static/%s", filename)
  err = c.SaveUploadedFile(header, filepath)
  if err != nil {
    c.JSON(http.StatusInternalServerError, gin.H{
      "msg": err.Error(),
    })
      return
  }

  // 将文件元信息存入数据库
  size := header.Size
  f := File{
    Name:    filename,
    Size:    size,
    Path:    filepath,
    CreatedAt: time.Now(),
  }
  _,err = f.InsertFile()
  if err !=nil{
    c.JSON(http.StatusInternalServerError, gin.H{
        "msg": err.Error(),
    })
    return
  }
  c.JSON(http.StatusOK, gin.H{
    "msg": "Upload successful",
  })
})

In the above code, we successfully obtain the uploaded file from the Request Form, and then save the file to our server. . After that, we store the file metainformation in the database, where InsertFile() is the database operation function we create later.

3. File download

We write a simple download function to output the file content into the HTTP response for client downloading. The complete code is as follows:

func (file File) GetFile() (err error) {
  //打开文件并读取文件内容
  f, err := os.Open(file.Path)
  if err != nil {
      return
  }
  defer f.Close()

  w := bufio.NewWriter(file)

  b := make([]byte, 100)
  n := 0
  for {
      n, err = f.Read(b)
      if err != nil && err != io.EOF{
          return
      }
      w.Write(b[:n])
      if n == 0{
          break
      }
  }
  w.Flush()
  return
}

r.GET("/download", func(c *gin.Context) {
  fileName := c.Query("name")
  if len(fileName) == 0 {
    c.JSON(http.StatusBadRequest, gin.H{
      "msg": "invalid parameter",
    })
    return
  }

  file := File{
    Name: fileName,
  }
  err = file.GetFile()
  if err !=nil{
    c.JSON(http.StatusInternalServerError, gin.H{
      "msg": err.Error(),
    })
    return
  }
  c.Writer.Header().Add("Content-Disposition", fmt.Sprintf("attachment;filename=%s", fileName))
  c.Writer.Header().Add("Content-Type", "application/octet-stream")
  c.File(file.Path)
})

4. Storage Optimization

In a high-concurrency environment, file upload and download must be efficient. Therefore, we can use distributed storage to optimize this problem. CDN acceleration, object storage and other methods can be used.

5. Complete code

Next, we will host the complete code on Git.

Create the project directory, and then execute the following command in the terminal:

git init
echo "# fileServer" >> README.md
git add README.md
git commit -m "first commit"
git remote add origin git@github.com:username/fileServer.git
git push -u origin master

For the complete code, please refer to: https: //github.com/username/fileServer.

Note: Replace username with your GitHub username.

6. Summary

This article mainly introduces how to use Golang to develop a Web-based network disk service. Through this article, we can understand the basic usage of the Gin framework, Gorm library, and MySQL database, as well as how to implement operations such as file upload and download. The complete code provided in this article can help readers better understand the content described in this article and help in practical applications.

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