代碼結構

相關代碼

captcha/internal/captcha/generator.go

package captchaimport (_ "embed" // 👈 啟用 embed"image""image/color""image/draw""image/png""io""math/rand""golang.org/x/image/font""golang.org/x/image/font/opentype""golang.org/x/image/math/fixed"
)// 👇 嵌入字體文件
//
//go:embed font/font.ttf
var fontBytes []bytevar (white = color.RGBA{255, 255, 255, 255}black = color.RGBA{0, 0, 0, 255}
)func randomColor() color.Color {return color.RGBA{R: uint8(rand.Intn(256)),G: uint8(rand.Intn(256)),B: uint8(rand.Intn(256)),A: 255,}
}// CaptchaImage 生成驗證碼圖片并寫入 io.Writer
func CaptchaImage(question string, w io.Writer) error {initRand()const (width  = 150height = 70)img := image.NewRGBA(image.Rect(0, 0, width, height))draw.Draw(img, img.Bounds(), &image.Uniform{white}, image.Point{}, draw.Src)// 畫干擾線for i := 0; i < 5; i++ {drawLine(img, rand.Intn(width), rand.Intn(height), rand.Intn(width), rand.Intn(height), randomColor())}// 畫噪點for i := 0; i < 50; i++ {img.Set(rand.Intn(width), rand.Intn(height), black)}// 畫文字（使用 freetype 渲染）if err := drawTextWithFreetype(img, question, 10, 60, randomColor()); err != nil {return err}return png.Encode(w, img)
}func drawLine(img *image.RGBA, x1, y1, x2, y2 int, c color.Color) {dx := abs(x2 - x1)dy := abs(y2 - y1)var sx, sy intif x1 < x2 {sx = 1} else {sx = -1}if y1 < y2 {sy = 1} else {sy = -1}err := dx - dyfor {img.Set(x1, y1, c)if x1 == x2 && y1 == y2 {break}e2 := 2 * errif e2 > -dy {err -= dyx1 += sx}if e2 < dx {err += dxy1 += sy}}
}func drawTextWithFreetype(img *image.RGBA, text string, x, y int, _ color.Color) error {fontParsed, err := opentype.Parse(fontBytes)if err != nil {return err}face, err := opentype.NewFace(fontParsed, &opentype.FaceOptions{Size:    32,DPI:     72,Hinting: font.HintingNone,})if err != nil {return err}currentX := xfor _, char := range text {// 為每個字符生成隨機顏色charColor := randomColor()d := &font.Drawer{Dst:  img,Src:  image.NewUniform(charColor), // 👈 每個字符獨立顏色Face: face,Dot:  fixed.P(currentX, y),}d.DrawString(string(char))// 手動計算字符寬度（簡單估算，或使用 font.Measure）bounds, _ := font.BoundString(face, string(char))advance := (bounds.Max.X - bounds.Min.X).Ceil()currentX += advance + 2 // +2 為字符間距微調}return nil
}func abs(x int) int {if x < 0 {return -x}return x
}

internal/captcha/logic.go

// internal/captcha/logic.go
package captchaimport ("math/rand""strconv""strings"
)type CaptchaResult struct {Question stringAnswer   intToken    string
}func GenerateCaptcha() *CaptchaResult {initRand()a := rand.Intn(21) // 0-20b := rand.Intn(21)var op stringvar result intif rand.Intn(2) == 0 {op = "+"result = a + b} else {op = "-"if a < b {a, b = b, a}result = a - b}question := strconv.Itoa(a) + " " + op + " " + strconv.Itoa(b) + " = ?"return &CaptchaResult{Question: question,Answer:   result,Token:    randString(32),}
}func randString(n int) string {const letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"b := make([]byte, n)for i := range b {b[i] = letters[rand.Intn(len(letters))]}return string(b)
}func ValidateAnswer(token string, userInput string, getAnswer func(string) (string, error)) bool {userInput = strings.TrimSpace(userInput)ansStr, err := getAnswer(token)if err != nil {return false}expected, err := strconv.Atoi(ansStr)if err != nil {return false}given, err := strconv.Atoi(userInput)return err == nil && given == expected
}

internal/captcha/rand.go

// internal/captcha/rand.go
package captchaimport ("math/rand""sync""time"
)var (randInit sync.Once
)func initRand() {randInit.Do(func() {rand.Seed(time.Now().UnixNano())})
}

pkg/redis/redis.go

// pkg/redis/redis.go
package redisimport ("context""time""github.com/go-redis/redis/v8"
)type Client struct {*redis.Client
}func NewClient(addr, password string, db int) *Client {rdb := redis.NewClient(&redis.Options{Addr:     addr,Password: password,DB:       db,})return &Client{rdb}
}func (c *Client) SetCaptcha(ctx context.Context, key string, answer int, expiration time.Duration) error {return c.Set(ctx, key, answer, expiration).Err()
}func (c *Client) GetCaptcha(ctx context.Context, key string) (string, error) {return c.Get(ctx, key).Result()
}func (c *Client) DeleteCaptcha(ctx context.Context, key string) error {return c.Del(ctx, key).Err()
}

main.go

// main.go
package mainimport ("context""fmt""go_collect/captcha/internal/captcha""go_collect/captcha/pkg/redis""log""net/http""time""github.com/gin-gonic/gin"
)var redisClient *redis.Clientfunc init() {// 生產環境應從配置文件或環境變量讀取redisClient = redis.NewClient("localhost:6377", "", 0)// 測試連接if err := redisClient.Ping(context.Background()).Err(); err != nil {log.Fatal("? Redis 連接失敗:", err)}fmt.Println("? Redis 連接成功")
}func main() {r := gin.Default()// 獲取驗證碼圖片r.GET("/captcha", getCaptchaHandler)// 驗證答案r.POST("/captcha/verify", verifyCaptchaHandler)r.Run(":8088")
}func getCaptchaHandler(c *gin.Context) {// 生成邏輯cap := captcha.GenerateCaptcha()// 緩存答案到 Redis，5分鐘過期ctx := context.Background()err := redisClient.SetCaptcha(ctx, cap.Token, cap.Answer, 5*time.Minute)if err != nil {c.JSON(http.StatusInternalServerError, gin.H{"error": "生成驗證碼失敗"})return}// 設置響應頭c.Header("Content-Type", "image/png")c.Header("X-Captcha-Token", cap.Token) // 前端需讀取此 Header 或返回 JSON// 生成圖片err = captcha.CaptchaImage(cap.Question, c.Writer)if err != nil {c.JSON(http.StatusInternalServerError, gin.H{"error": "渲染圖片失敗"})return}
}type VerifyRequest struct {Token  string `json:"token" binding:"required"`Answer string `json:"answer" binding:"required"`
}func verifyCaptchaHandler(c *gin.Context) {var req VerifyRequestif err := c.ShouldBindJSON(&req); err != nil {c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})return}// 校驗答案isValid := captcha.ValidateAnswer(req.Token, req.Answer, func(token string) (string, error) {ans, err := redisClient.GetCaptcha(context.Background(), token)if err != nil {return "", err}// 驗證后刪除，防止重復使用redisClient.DeleteCaptcha(context.Background(), token)return ans, nil})if isValid {c.JSON(http.StatusOK, gin.H{"success": true,"message": "驗證通過",})} else {c.JSON(http.StatusOK, gin.H{"success": false,"message": "驗證失敗",})}
}

調用

http://localhost:8088/captcha

驗證

http://localhost:8088/captcha/verify
{"token":"sWmHAreIaA5jC7WqshKHXOjDMTH4I9kV","answer":"7"
}
{"message": "驗證通過","success": true
}