refactor(go)!: 分离练习区与独立项目区
- 将现有练习及 module 文件迁移至 go/practice，保持代码和依赖不变 - 新增 go/projects 项目区说明，更新目录约定与开发命令 BREAKING CHANGE: Go 练习命令需改在 go/practice 目录下执行
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package main
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import (
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"context"
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"fmt"
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"math/rand"
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"net/http"
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_ "net/http/pprof"
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"time"
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)
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// 来自文章 https://www.cnblogs.com/hwnd/p/20682814
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func simulateRequest() {
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timeout := 500 * time.Millisecond
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ctx, cancel := context.WithDeadline(context.Background(), time.Now().Add(timeout))
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defer cancel()
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resultCh := make(chan string) // 无缓冲！
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// 启动 worker goroutine 处理"请求"
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go func() {
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time.Sleep(time.Duration(rand.Intn(500)+300) * time.Millisecond)
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select {
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case <-time.After(timeout):
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fmt.Println("worker 超时，放弃处理")
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case <-ctx.Done():
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case resultCh <- fmt.Sprintf("处理完成，耗时 %dms", rand.Intn(500)+300):
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}
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}()
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// TODO: 模拟请求取消或超时的情况（比如 500ms 后调用方不再关心结果）
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// 如果 worker 还没完成，它就 leak 了
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select {
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case resultCh := <-resultCh:
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fmt.Println(resultCh)
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case <-ctx.Done():
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fmt.Println("请求方取消了请求")
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}
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}
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func main() {
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for i := 0; i < 5; i++ {
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simulateRequest()
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fmt.Printf("第 %d 个请求处理完毕\n\n", i+1)
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time.Sleep(200 * time.Millisecond)
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}
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fmt.Println("所有请求处理完毕")
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// 运行后观察：goroutine 数量只增不减
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http.ListenAndServe(":6060", nil)
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}
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package main
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import (
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"fmt"
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)
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type User struct {
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Name string
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}
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func NewUser() *User {
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u := User{}
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return &u
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}
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func ClosureFunc() func() int {
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a := 1
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return func() int {
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return a
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}
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}
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func main() {
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fmt.Println(NewUser())
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cf:= ClosureFunc()
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fmt.Println(cf())
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}
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@@ -0,0 +1,56 @@
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package main
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import (
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"log"
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"net/http"
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_ "net/http/pprof" // 注册 pprof 相关 handler
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"time"
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)
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// memoryBlocks 保留一部分内存块，方便内存剖析观察。
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// 这个全局变量会一直存活，便于分析堆上的对象。
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var memoryBlocks [64][]byte
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func main() {
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// 启动 pprof HTTP 服务
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go func() {
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log.Println("pprof server started at http://localhost:6060/debug/pprof/")
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if err := http.ListenAndServe("localhost:6060", nil); err != nil {
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log.Fatal(err)
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}
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}()
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// 模拟 CPU 密集型业务
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go cpuIntensiveTask()
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// 模拟内存分配型业务
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go memoryIntensiveTask()
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// 阻塞主协程，让程序持续运行
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select {}
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}
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// fib 递归计算斐波那契数列，非常耗费 CPU
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func fib(n int) int {
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if n <= 1 {
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return n
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}
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return fib(n-1) + fib(n-2)
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}
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// cpuIntensiveTask 循环执行 CPU 密集型计算
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func cpuIntensiveTask() {
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for {
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_ = fib(30)
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}
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}
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// memoryIntensiveTask 循环分配内存并保留在全局切片中
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func memoryIntensiveTask() {
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for i := 0; ; i++ {
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idx := i % len(memoryBlocks)
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// 每次分配 1MB，替换掉旧的内存块
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memoryBlocks[idx] = make([]byte, 1<<20) // 1 << 20 = 1MB
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time.Sleep(100 * time.Millisecond)
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}
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}
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@@ -0,0 +1,34 @@
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package main
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import (
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"fmt"
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"runtime"
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)
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var retained [][]byte // 全局变量，用来保持对象可达
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func printMemory(stage string) {
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var m runtime.MemStats
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runtime.ReadMemStats(&m)
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fmt.Printf("%s: HeapAlloc=%d MiB, TotalAlloc=%d MiB\n",
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stage,
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m.HeapAlloc/1024/1024,
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m.TotalAlloc/1024/1024)
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}
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func main() {
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runtime.GC()
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printMemory("开始")
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for i := 0; i < 20; i++ {
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block := make([]byte, 1024*1024) // 每次创建约 1 MiB 的底层数组
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block[0] = byte(i)
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retained = append(retained, block)
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}
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printMemory("分配后")
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retained = nil // 程序不再持有这些数组
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runtime.GC()
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printMemory("GC 后")
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}
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@@ -0,0 +1,116 @@
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package main
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import (
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"net/http"
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"time"
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"github.com/gin-contrib/sessions"
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"github.com/gin-contrib/sessions/cookie"
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"github.com/gin-gonic/gin"
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)
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var (
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mockUsers = map[string]string{
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"zhangsan": "123456",
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"lisi": "654321",
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}
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// secretKey = "your-secret-key"
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hmacSecretKey = "5KiinhGcvoXFmgOttvgMWd9ugadE0KVP"
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blockSecretKey = "OLZmfTWHGyjCfJoH1Y8SjbSY"
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)
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const sessionTTL = 60 * 5
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func sessionOptions(maxAge int) sessions.Options {
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return sessions.Options{
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Path: "/",
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Domain: "", // 设置为 "" 表示当前域名
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MaxAge: maxAge, // 单位为秒。0 表示不写Max-Age(浏览器会话cookie); -1 表示删除 cookie
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Secure: false, // 生产走 HTTPS 时改 true
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HttpOnly: true, // true 表示禁止 JS 读取 cookie
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SameSite: http.SameSiteStrictMode, // 严格模式，仅在同源请求中发送 cookie
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}
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}
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// 代码来自文章 https://www.cnblogs.com/XY-Heruo/p/22864951
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func main() {
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r := gin.Default()
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// Create cookie-based session store with a secret key
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// 传单个密钥时, 只做签名认证，不加密cookie内容. 认证密钥建议 32 或 64 字节
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// 传一对密钥时，第一个用于认证（HMAC），第二个用于加密（AES-128, AES-192, AES-256）。加密密钥必须是16、24或32字节长度，对应 AES-128/192/256。
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// 多对密钥用于密钥轮换，第一对用于当前加密和认证，后续的用于解密和认证旧的cookie。Example: cookie.NewStore([]byte("newAuth"), []byte("newEnc"), []byte("oldAuth"), []byte("oldEnc"))
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store := cookie.NewStore([]byte(hmacSecretKey), []byte(blockSecretKey))
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store.Options(sessionOptions(sessionTTL)) // 全局设置 cookie 过期时间为 5 分钟
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r.Use(sessions.Sessions("mysession", store))
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r.POST("/login", login)
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auth := r.Group("/", authRequired())
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auth.GET("/profile", profile)
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auth.POST("/logout", logout)
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r.Run(":8080")
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}
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func login(c *gin.Context) {
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session := sessions.Default(c)
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username := c.PostForm("username")
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password := c.PostForm("password")
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if username == "" || password == "" {
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c.JSON(http.StatusBadRequest, gin.H{"error": "username or password is empty"})
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return
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}
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if mockUsers[username] != password {
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c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid username or password"})
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return
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}
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session.Set("user", username)
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session.Set("expire_at", time.Now().Add(time.Second*sessionTTL).Unix()) // 设置过期时间
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if err := session.Save(); err != nil {
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c.JSON(http.StatusInternalServerError, gin.H{"error": "save session failed"})
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return
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}
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c.JSON(http.StatusOK, gin.H{"message": "logged in"})
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}
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func logout(c *gin.Context) {
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session := sessions.Default(c)
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session.Clear()
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session.Options(sessionOptions(-1)) // 让浏览器删除 cookie
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if err := session.Save(); err != nil {
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c.JSON(http.StatusInternalServerError, gin.H{"error": "save session failed"})
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return
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}
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c.JSON(http.StatusOK, gin.H{"message": "logged out"})
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}
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func profile(c *gin.Context) {
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session := sessions.Default(c)
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user := session.Get("user").(string)
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c.JSON(http.StatusOK, gin.H{"user": user})
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}
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func authRequired() gin.HandlerFunc {
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return func(c *gin.Context) {
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session := sessions.Default(c)
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if session.Get("user") == nil {
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c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "unauthorized"})
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return
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}
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if expireAt, ok := session.Get("expire_at").(int64); !ok || time.Now().Unix() > expireAt {
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session.Clear()
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session.Options(sessionOptions(-1))
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session.Save()
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c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "expired session"})
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return
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}
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c.Next()
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}
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}
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