Bagaimana untuk membangunkan sistem pengurusan fail mudah menggunakan MySQL dan bahasa Go

go get github.com/go-sql-driver/mysql

package main

import (
    "database/sql"
    "fmt"

    _ "github.com/go-sql-driver/mysql"
)

// 数据库连接信息
const (
    DBUsername = "your_username"
    DBPassword = "your_password"
    DBHost     = "your_host"
    DBPort     = "your_port"
    DBName     = "your_database_name"
)

func main() {
    // 构建连接字符串
    connStr := fmt.Sprintf("%s:%s@tcp(%s:%s)/%s", DBUsername, DBPassword, DBHost, DBPort, DBName)

    // 连接数据库
    db, err := sql.Open("mysql", connStr)
    if err != nil {
        fmt.Println("Failed to connect to database:", err)
        return
    }
    defer db.Close()

    // 查询用户表
    rows, err := db.Query("SELECT id, username, password FROM User")
    if err != nil {
        fmt.Println("Failed to query user table:", err)
        return
    }
    defer rows.Close()

    // 遍历查询结果
    for rows.Next() {
        var id int
        var username, password string
        err := rows.Scan(&id, &username, &password)
        if err != nil {
            fmt.Println("Failed to scan user table:", err)
            return
        }
        fmt.Println(id, username, password)
    }
}

package main

import (
    "database/sql"
    "fmt"
    "io"
    "net/http"
    "os"

    _ "github.com/go-sql-driver/mysql"
)

// 数据库连接信息
const (
    DBUsername = "your_username"
    DBPassword = "your_password"
    DBHost     = "your_host"
    DBPort     = "your_port"
    DBName     = "your_database_name"
)

func main() {
    // 构建连接字符串
    connStr := fmt.Sprintf("%s:%s@tcp(%s:%s)/%s", DBUsername, DBPassword, DBHost, DBPort, DBName)

    // 连接数据库
    db, err := sql.Open("mysql", connStr)
    if err != nil {
        fmt.Println("Failed to connect to database:", err)
        return
    }
    defer db.Close()

    // 上传文件接口
    http.HandleFunc("/upload", func(w http.ResponseWriter, r *http.Request) {
        // 解析文件
        file, header, err := r.FormFile("file")
        if err != nil {
            fmt.Println("Failed to parse file:", err)
            return
        }
        defer file.Close()

        // 创建文件
        dst, err := os.Create("/path/to/save/" + header.Filename)
        if err != nil {
            fmt.Println("Failed to create file:", err)
            return
        }
        defer dst.Close()

        // 复制文件
        _, err = io.Copy(dst, file)
        if err != nil {
            fmt.Println("Failed to copy file:", err)
            return
        }

        // 插入文件表
        _, err = db.Exec("INSERT INTO File (filename, filepath) VALUES (?, ?)", header.Filename, dst.Name())
        if err != nil {
            fmt.Println("Failed to insert into file table:", err)
            return
        }

        fmt.Fprintln(w, "File uploaded successfully!")
    })

    // 下载文件接口
    http.HandleFunc("/download", func(w http.ResponseWriter, r *http.Request) {
        filename := r.URL.Query().Get("filename")

        // 查询文件路径
        var filepath string
        err := db.QueryRow("SELECT filepath FROM File WHERE filename = ?", filename).Scan(&filepath)
        if err != nil {
            fmt.Println("Failed to query file table:", err)
            return
        }

        // 打开文件
        file, err := os.Open(filepath)
        if err != nil {
            fmt.Println("Failed to open file:", err)
            return
        }
        defer file.Close()

        // 设置响应头
        w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=%s", filename))
        w.Header().Set("Content-Type", "application/octet-stream")

        // 写入文件内容
        _, err = io.Copy(w, file)
        if err != nil {
            fmt.Println("Failed to write file:", err)
            return
        }
    })

    // 启动HTTP服务器
    fmt.Println("Server started on http://localhost:8080")
    http.ListenAndServe(":8080", nil)
}