- 基本中间件结构：
// 基本中间件函数签名
func MiddlewareName() gin.HandlerFunc {return func(c *gin.Context) {// 处理请求前的逻辑c.Next() // 处理下一个中间件或处理函数// 处理请求后的逻辑}
}
- 常用中间件示例：
package middlewareimport ("github.com/gin-gonic/gin""log""time"
)// 日志中间件
func Logger() gin.HandlerFunc {return func(c *gin.Context) {start := time.Now()path := c.Request.URL.Pathc.Next()latency := time.Since(start)statusCode := c.Writer.Status()log.Printf("Path: %s | Status: %d | Latency: %v", path, statusCode, latency)}
}// 认证中间件
func Auth() gin.HandlerFunc {return func(c *gin.Context) {token := c.GetHeader("Authorization")if token == "" {c.JSON(401, gin.H{"error": "Authorization token required"})c.Abort()return}// 验证 tokenif !validateToken(token) {c.JSON(401, gin.H{"error": "Invalid token"})c.Abort()return}c.Next()}
}// 错误处理中间件
func ErrorHandler() gin.HandlerFunc {return func(c *gin.Context) {defer func() {if err := recover(); err != nil {c.JSON(500, gin.H{"error": "Internal Server Error",})}}()c.Next()}
}// CORS 中间件
func CORS() gin.HandlerFunc {return func(c *gin.Context) {c.Writer.Header().Set("Access-Control-Allow-Origin", "*")c.Writer.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")c.Writer.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization")if c.Request.Method == "OPTIONS" {c.AbortWithStatus(204)return}c.Next()}
}
- 中间件的使用方式：
package mainimport ("github.com/gin-gonic/gin""your-project/middleware"
)func main() {r := gin.Default()// 全局中间件r.Use(middleware.Logger())r.Use(middleware.ErrorHandler())// 路由组中间件authorized := r.Group("/api")authorized.Use(middleware.Auth()){authorized.GET("/users", GetUsers)authorized.POST("/users", CreateUser)}// 单个路由中间件r.GET("/public", middleware.CORS(), PublicHandler)r.Run(":8080")
}
- 带配置的中间件：
// 限流中间件
func RateLimit(limit int, duration time.Duration) gin.HandlerFunc {limiter := rate.NewLimiter(rate.Every(duration), limit)return func(c *gin.Context) {if !limiter.Allow() {c.JSON(429, gin.H{"error": "Too many requests"})c.Abort()return}c.Next()}
}// 缓存中间件
func Cache(duration time.Duration) gin.HandlerFunc {cache := make(map[string]cacheEntry)type cacheEntry struct {data interface{}timestamp time.Time}return func(c *gin.Context) {key := c.Request.URL.Path// 检查缓存if entry, exists := cache[key]; exists {if time.Since(entry.timestamp) < duration {c.JSON(200, entry.data)c.Abort()return}}c.Next()// 存储响应到缓存cache[key] = cacheEntry{data: c.Keys["response"],timestamp: time.Now(),}}
}
- 自定义上下文：
// 自定义上下文
type CustomContext struct {*gin.ContextUser *models.User
}// 用户上下文中间件
func UserContext() gin.HandlerFunc {return func(c *gin.Context) {user := getCurrentUser(c)customContext := &CustomContext{Context: c,User: user,}c.Set("custom_context", customContext)c.Next()}
}
- 链式中间件：
// 请求链路追踪
func RequestTracing() gin.HandlerFunc {return func(c *gin.Context) {traceID := generateTraceID()c.Set("trace_id", traceID)c.Next()// 记录请求完成log.Printf("Request completed: %s", traceID)}
}// 性能监控中间件
func Performance() gin.HandlerFunc {return func(c *gin.Context) {start := time.Now()c.Next()duration := time.Since(start)if duration > time.Second {log.Printf("Slow request: %s took %v", c.Request.URL.Path, duration)}}
}
- 中间件通信：
// 设置和获取中间件数据
func DataMiddleware() gin.HandlerFunc {return func(c *gin.Context) {// 设置数据c.Set("key", "value")c.Next()// 获取数据value, exists := c.Get("key")if exists {// 使用数据}}
}// 响应修改中间件
func ResponseModifier() gin.HandlerFunc {return func(c *gin.Context) {c.Next()// 修改响应status := c.Writer.Status()if status >= 400 {c.JSON(status, gin.H{"error": true,"message": c.Keys["error"],})}}
}
- 高级中间件示例：
// JWT 认证中间件
func JWTAuth() gin.HandlerFunc {return func(c *gin.Context) {token := c.GetHeader("Authorization")if token == "" {c.JSON(401, gin.H{"error": "No token provided"})c.Abort()return}claims, err := parseToken(token)if err != nil {c.JSON(401, gin.H{"error": "Invalid token"})c.Abort()return}c.Set("user_id", claims.UserID)c.Next()}
}// 请求验证中间件
func ValidateRequest(schema interface{}) gin.HandlerFunc {return func(c *gin.Context) {if err := c.ShouldBindJSON(schema); err != nil {c.JSON(400, gin.H{"error": err.Error()})c.Abort()return}c.Set("validated_data", schema)c.Next()}
}// 请求限制中间件
func RequestLimit(maxRequests int, duration time.Duration) gin.HandlerFunc {clients := make(map[string][]time.Time)mu := &sync.Mutex{}return func(c *gin.Context) {ip := c.ClientIP()now := time.Now()mu.Lock()defer mu.Unlock()// 清理过期的请求记录clients[ip] = filterOldRequests(clients[ip], now.Add(-duration))if len(clients[ip]) >= maxRequests {c.JSON(429, gin.H{"error": "Too many requests"})c.Abort()return}clients[ip] = append(clients[ip], now)c.Next()}
}
- 测试中间件：
func TestAuthMiddleware(t *testing.T) {// 创建测试路由r := gin.New()r.Use(Auth())r.GET("/test", func(c *gin.Context) {c.JSON(200, gin.H{"message": "success"})})// 创建测试请求w := httptest.NewRecorder()req, _ := http.NewRequest("GET", "/test", nil)// 不带 token 的请求r.ServeHTTP(w, req)assert.Equal(t, 401, w.Code)// 带有效 token 的请求w = httptest.NewRecorder()req.Header.Set("Authorization", "valid-token")r.ServeHTTP(w, req)assert.Equal(t, 200, w.Code)
}
- 中间件最佳实践：
// 中间件工厂
type MiddlewareConfig struct {EnableLogging boolLogLevel stringTimeout time.Duration
}func NewMiddleware(config MiddlewareConfig) gin.HandlerFunc {return func(c *gin.Context) {if config.EnableLogging {// 启用日志}// 设置超时ctx, cancel := context.WithTimeout(c.Request.Context(), config.Timeout)defer cancel()c.Request = c.Request.WithContext(ctx)done := make(chan bool)go func() {c.Next()done <- true}()select {case <-done:returncase <-ctx.Done():c.JSON(504, gin.H{"error": "request timeout"})c.Abort()}}
}
使用这些中间件时，需要注意：
- 中间件的执行顺序很重要
- 合理使用
c.Next()和c.Abort() - 避免在中间件中存储太多数据
- 注意性能影响
- 做好错误处理
- 保持中间件的独立性和可复用性