Web 框架 Gin / Echo

go get github.com/gin-gonic/gin@latest

package main

import (
	"net/http"

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

func main() {
	// gin.Default() = gin.New() + Logger() + Recovery()
	// Logger：每个请求打一行日志；Recovery：panic 时返回 500 而非挂进程
	r := gin.Default()

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

	// 默认监听 :8080；也可 r.Run(":9090") 指定端口
	r.Run(":8080")
}

go run main.go
curl "http://localhost:8080/ping"
# {"message":"pong"}

package main

import (
	"net/http"

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

func main() {
	r := gin.Default()

	// 查询参数 ?page=2
	r.GET("/users", func(c *gin.Context) {
		page := c.DefaultQuery("page", "1")   // 默认值版
		size := c.Query("size")               // 无默认值版
		c.JSON(http.StatusOK, gin.H{
			"page": page,
			"size": size,
		})
	})

	// 路径参数 /users/42
	r.GET("/users/:id", func(c *gin.Context) {
		id := c.Param("id")
		c.JSON(http.StatusOK, gin.H{"id": id})
	})

	// 通配参数 /files/2026/08/report.pdf
	r.GET("/files/*path", func(c *gin.Context) {
		c.JSON(http.StatusOK, gin.H{"path": c.Param("path")})
	})

	// POST 也是声明式注册
	r.POST("/users", func(c *gin.Context) {
		c.JSON(http.StatusOK, gin.H{"created": true})
	})

	r.Run(":8080")
}

package main

import (
	"net/http"
	"time"

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

func main() {
	r := gin.Default()

	// 顶层「健康检查」不分组
	r.GET("/healthz", func(c *gin.Context) {
		c.JSON(http.StatusOK, gin.H{"status": "up"})
	})

	// v1 分组：统一前缀 /api/v1，额外挂一个计时中间件
	v1 := r.Group("/api/v1", timing())
	{
		v1.GET("/users", listUsers)
		v1.GET("/users/:id", getUser)
		v1.POST("/users", createUser)
	}

	// v2 分组（演示未来接口演进，独立挂中间件）
	v2 := r.Group("/api/v2")
	v2.GET("/users", listUsersV2)

	r.Run(":8080")
}

func timing() gin.HandlerFunc {
	return func(c *gin.Context) {
		start := time.Now()
		c.Next()
		c.Header("X-Duration", time.Since(start).String())
	}
}

func listUsers(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{"api": "v1", "users": []string{}})
}
func getUser(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{"id": c.Param("id")})
}
func createUser(c *gin.Context) {
	c.JSON(http.StatusCreated, gin.H{"created": true})
}
func listUsersV2(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{"api": "v2"})
}

package main

import (
	"net/http"
	"time"

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

// 绑定 + 校验 tag 全在结构体上声明
type CreateUserReq struct {
	Username string    `json:"username" binding:"required"`       // 必填
	Email    string    `json:"email" binding:"required,email"`    // 必填 + 邮箱格式
	Age      int       `json:"age" binding:"gte=0,lte=150"`       // 范围校验
	Password string    `json:"password" binding:"required,min=8"` // 至少 8 位
	Tags     []string  `json:"tags" binding:"dive,required"`      // 切片内每个元素必填
	Birth    time.Time `json:"birth"`                             // 无校验，可选
}

type UserResp struct {
	ID       uint   `json:"id"`
	Username string `json:"username"`
}

func main() {
	r := gin.Default()

	r.POST("/api/v1/users", func(c *gin.Context) {
		var req CreateUserReq
		// ShouldBindJSON：绑定失败/校验失败都会返回 error
		if err := c.ShouldBindJSON(&req); err != nil {
			// 400：把校验细节回给客户端便于排查
			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
			return
		}
		c.JSON(http.StatusCreated, UserResp{ID: 1, Username: req.Username})
	})

	r.Run(":8080")
}

curl -X POST "http://localhost:8080/api/v1/users" \
     -H "Content-Type: application/json" \
     -d '{"username":"tom","email":"bad","password":"123"}'
# 400，error 提示 email 格式不对、password 太短（一次全报）

package main

import (
	"fmt"
	"time"

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

// 自定义：打印每个请求耗时
func latency() gin.HandlerFunc {
	return func(c *gin.Context) {
		start := time.Now()
		c.Next() // 放行，handler 链继续
		fmt.Printf("耗时: %v (route: %s)\n", time.Since(start), c.FullPath())
	}
}

// 自定义：简单的请求 ID
func requestID() gin.HandlerFunc {
	return func(c *gin.Context) {
		c.Header("X-Request-ID", fmt.Sprintf("%d", time.Now().UnixNano()))
		c.Next()
	}
}

func main() {
	// 全局中间件
	r := gin.New() // 不用 Default：自己精确装组件
	r.Use(gin.Logger(), gin.Recovery(), latency(), requestID())

	// 路由级中间件（只对这条路由生效）
	r.GET("/admin", authRequired(), func(c *gin.Context) {
		c.String(200, "admin only")
	})

	r.Run(":8080")
}

func authRequired() gin.HandlerFunc {
	return func(c *gin.Context) {
		if c.GetHeader("Authorization") == "" {
			c.AbortWithStatusJSON(401, gin.H{"error": "no token"})
			return // Abort 后不调用 c.Next()，链路终止
		}
		c.Next()
	}
}

package main

import (
	"net/http"

	"github.com/labstack/echo/v4"
)

type LoginReq struct {
	Username string `json:"username" validate:"required"`
	Password string `json:"password" validate:"required"`
}

func main() {
	e := echo.New()

	e.GET("/users/:id", func(c echo.Context) error {
		id := c.Param("id")
		return c.JSON(http.StatusOK, map[string]string{"id": id})
	})

	e.POST("/login", func(c echo.Context) error {
		var req LoginReq
		if err := c.Bind(&req); err != nil {
			return err // 返回 error，框架统一渲染
		}
		return c.JSON(http.StatusOK, map[string]string{"ok": "1"})
	})

	e.Logger.Fatal(e.Start(":8080"))
}