wip: 保存 Go 练习和技术笔记

2026-09-24 14:16:17 +08:00
parent 64cc3ec381
commit babd8f2793
20 changed files with 1229 additions and 29 deletions
@@ -0,0 +1,100 @@
+package linkedlist
+
+import (
+	"fmt"
+	"strings"
+)
+
+// Node 是单向链表的一个节点,持有数据与指向下一个节点的指针。
+type Node[T comparable] struct {
+	Data T
+	Next *Node[T]
+}
+
+// LinkedList 是持有头指针的单向链表,零值即为空表。
+type LinkedList[T comparable] struct {
+	head *Node[T]
+}
+
+// InsertHead 将新节点插入表头。
+func (l *LinkedList[T]) InsertHead(data T) {
+	l.head = &Node[T]{Data: data, Next: l.head}
+}
+
+// InsertTail 将新节点追加到表尾;空表时新节点直接成为表头。
+func (l *LinkedList[T]) InsertTail(data T) {
+	newNode := &Node[T]{Data: data}
+	if l.head == nil {
+		l.head = newNode
+		return
+	}
+	current := l.head
+	for current.Next != nil {
+		current = current.Next
+	}
+	current.Next = newNode
+}
+
+// DeleteHead 删除表头节点;空表时无操作。
+func (l *LinkedList[T]) DeleteHead() {
+	if l.head != nil {
+		l.head = l.head.Next
+	}
+}
+
+// DeleteTail 删除表尾节点;空表时无操作,仅剩一个节点时表变空。
+func (l *LinkedList[T]) DeleteTail() {
+	switch {
+	case l.head == nil:
+	case l.head.Next == nil:
+		l.head = nil
+	default:
+		current := l.head
+		for current.Next.Next != nil {
+			current = current.Next
+		}
+		current.Next = nil
+	}
+}
+
+// Search 返回首个 Data 等于 data 的节点;不存在时返回 nil。
+func (l *LinkedList[T]) Search(data T) *Node[T] {
+	for current := l.head; current != nil; current = current.Next {
+		if current.Data == data {
+			return current
+		}
+	}
+	return nil
+}
+
+// Len 返回链表的节点个数。
+func (l *LinkedList[T]) Len() int {
+	count := 0
+	for current := l.head; current != nil; current = current.Next {
+		count++
+	}
+	return count
+}
+
+// Reverse 原地反转链表。
+func (l *LinkedList[T]) Reverse() {
+	var prev, current *Node[T]
+	current = l.head
+	for current != nil {
+		next := current.Next
+		current.Next = prev
+		prev = current
+		current = next
+	}
+	l.head = prev
+}
+
+// String 以 "1 -> 2 -> nil" 的格式输出整条链,便于打印与调试。
+func (l LinkedList[T]) String() string {
+	var sb strings.Builder
+	for current := l.head; current != nil; current = current.Next {
+		fmt.Fprintf(&sb, "%v -> ", current.Data)
+	}
+	sb.WriteString("nil")
+	return sb.String()
+}
@@ -0,0 +1,29 @@
+package main
+
+import (
+	"fmt"
+
+	"lab/algorithms/linkedlist"
+)
+
+func main() {
+	var list linkedlist.LinkedList[int] // 零值即为空表
+	list.InsertTail(3)
+	list.InsertTail(5)
+	list.InsertHead(1)
+	list.InsertHead(0)
+	fmt.Println(&list) // 0 -> 1 -> 3 -> 5 -> nil
+
+	list.DeleteHead()
+	list.DeleteTail()
+	fmt.Println(&list) // 1 -> 3 -> nil
+
+	found := list.Search(3)
+	if found != nil {
+		fmt.Printf("找到节点,Data = %d\n", found.Data)
+	}
+
+	list.Reverse()
+	fmt.Println(&list) // 3 -> 1 -> nil
+	fmt.Printf("链表长度: %d\n", list.Len())
+}
@@ -0,0 +1,50 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"math/rand"
+	"net/http"
+	_ "net/http/pprof"
+	"time"
+)
+
+// 来自文章 https://www.cnblogs.com/hwnd/p/20682814
+func simulateRequest() {
+	timeout := 500 * time.Millisecond
+	ctx, cancel := context.WithDeadline(context.Background(), time.Now().Add(timeout))
+	defer cancel()
+	resultCh := make(chan string) // 无缓冲！
+
+	// 启动 worker goroutine 处理"请求"
+	go func() {
+		time.Sleep(time.Duration(rand.Intn(500)+300) * time.Millisecond)
+		select {
+		case <-time.After(timeout):
+			fmt.Println("worker 超时，放弃处理")
+		case <-ctx.Done():
+		case resultCh <- fmt.Sprintf("处理完成，耗时 %dms", rand.Intn(500)+300):
+
+		}
+	}()
+
+	// 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）
+	// 如果 worker 还没完成，它就 leak 了
+	select {
+	case resultCh := <-resultCh:
+		fmt.Println(resultCh)
+	case <-ctx.Done():
+		fmt.Println("请求方取消了请求")
+	}
+}
+
+func main() {
+	for i := 0; i < 5; i++ {
+		simulateRequest()
+		fmt.Printf("第 %d 个请求处理完毕\n\n", i+1)
+		time.Sleep(200 * time.Millisecond)
+	}
+	fmt.Println("所有请求处理完毕")
+	// 运行后观察：goroutine 数量只增不减
+	http.ListenAndServe(":6060", nil)
+}
@@ -0,0 +1,56 @@
+package main
+
+import (
+	"log"
+	"net/http"
+	_ "net/http/pprof" // 注册 pprof 相关 handler
+	"time"
+)
+
+// memoryBlocks 保留一部分内存块，方便内存剖析观察。
+// 这个全局变量会一直存活，便于分析堆上的对象。
+var memoryBlocks [64][]byte
+
+func main() {
+	// 启动 pprof HTTP 服务
+	go func() {
+		log.Println("pprof server started at http://localhost:6060/debug/pprof/")
+		if err := http.ListenAndServe("localhost:6060", nil); err != nil {
+			log.Fatal(err)
+		}
+	}()
+
+	// 模拟 CPU 密集型业务
+	go cpuIntensiveTask()
+
+	// 模拟内存分配型业务
+	go memoryIntensiveTask()
+
+	// 阻塞主协程，让程序持续运行
+	select {}
+}
+
+// fib 递归计算斐波那契数列，非常耗费 CPU
+func fib(n int) int {
+	if n <= 1 {
+		return n
+	}
+	return fib(n-1) + fib(n-2)
+}
+
+// cpuIntensiveTask 循环执行 CPU 密集型计算
+func cpuIntensiveTask() {
+	for {
+		_ = fib(30)
+	}
+}
+
+// memoryIntensiveTask 循环分配内存并保留在全局切片中
+func memoryIntensiveTask() {
+	for i := 0; ; i++ {
+		idx := i % len(memoryBlocks)
+		// 每次分配 1MB，替换掉旧的内存块
+		memoryBlocks[idx] = make([]byte, 1<<20) // 1 << 20 = 1MB
+		time.Sleep(100 * time.Millisecond)
+	}
+}
@@ -0,0 +1,116 @@
+package main
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/gin-contrib/sessions"
+	"github.com/gin-contrib/sessions/cookie"
+	"github.com/gin-gonic/gin"
+)
+
+var (
+	mockUsers = map[string]string{
+		"zhangsan": "123456",
+		"lisi":     "654321",
+	}
+	// secretKey = "your-secret-key"
+	hmacSecretKey  = "5KiinhGcvoXFmgOttvgMWd9ugadE0KVP"
+	blockSecretKey = "OLZmfTWHGyjCfJoH1Y8SjbSY"
+)
+
+const sessionTTL = 60 * 5
+
+func sessionOptions(maxAge int) sessions.Options {
+	return sessions.Options{
+		Path:     "/",
+		Domain:   "",                      // 设置为 "" 表示当前域名
+		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
+		Secure:   false,                   // 生产走 HTTPS 时改 true
+		HttpOnly: true,                    // true 表示禁止 JS 读取 cookie
+		SameSite: http.SameSiteStrictMode, // 严格模式，仅在同源请求中发送 cookie
+	}
+}
+
+// 代码来自文章 https://www.cnblogs.com/XY-Heruo/p/22864951
+func main() {
+	r := gin.Default()
+
+	// Create cookie-based session store with a secret key
+	// 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
+	// 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。
+	// 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"))
+	store := cookie.NewStore([]byte(hmacSecretKey), []byte(blockSecretKey))
+	store.Options(sessionOptions(sessionTTL)) // 全局设置 cookie 过期时间为 5 分钟
+	r.Use(sessions.Sessions("mysession", store))
+
+	r.POST("/login", login)
+
+	auth := r.Group("/", authRequired())
+
+	auth.GET("/profile", profile)
+	auth.POST("/logout", logout)
+
+	r.Run(":8080")
+}
+
+func login(c *gin.Context) {
+	session := sessions.Default(c)
+	username := c.PostForm("username")
+	password := c.PostForm("password")
+
+	if username == "" || password == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "username or password is empty"})
+		return
+	}
+
+	if mockUsers[username] != password {
+		c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid username or password"})
+		return
+	}
+
+	session.Set("user", username)
+	session.Set("expire_at", time.Now().Add(time.Second*sessionTTL).Unix()) // 设置过期时间
+	if err := session.Save(); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "save session failed"})
+		return
+	}
+
+	c.JSON(http.StatusOK, gin.H{"message": "logged in"})
+}
+
+func logout(c *gin.Context) {
+	session := sessions.Default(c)
+	session.Clear()
+	session.Options(sessionOptions(-1)) // 让浏览器删除 cookie
+	if err := session.Save(); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "save session failed"})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"message": "logged out"})
+}
+
+func profile(c *gin.Context) {
+	session := sessions.Default(c)
+	user := session.Get("user").(string)
+	c.JSON(http.StatusOK, gin.H{"user": user})
+}
+
+func authRequired() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		session := sessions.Default(c)
+		if session.Get("user") == nil {
+			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "unauthorized"})
+			return
+		}
+
+		if expireAt, ok := session.Get("expire_at").(int64); !ok || time.Now().Unix() > expireAt {
+			session.Clear()
+			session.Options(sessionOptions(-1))
+			session.Save()
+			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "expired session"})
+			return
+		}
+		c.Next()
+	}
+}
@@ -1,15 +1,43 @@
 module lab

-go 1.26.2
+go 1.27.0

 require (
-	github.com/richardlehane/mscfb v1.0.7 // indirect
-	github.com/richardlehane/msoleps v1.0.6 // indirect
-	github.com/tiendc/go-deepcopy v1.7.2 // indirect
-	github.com/xuri/efp v0.0.1 // indirect
-	github.com/xuri/excelize/v2 v2.11.0 // indirect
-	github.com/xuri/nfp v0.0.2-0.20250530014748-2ddeb826f9a9 // indirect
-	golang.org/x/crypto v0.53.0 // indirect
-	golang.org/x/net v0.56.0 // indirect
-	golang.org/x/text v0.38.0 // indirect
+	github.com/gin-contrib/sessions v1.1.2
+	github.com/gin-gonic/gin v1.12.0
+	golang.org/x/crypto v0.56.0
+)
+
+require (
+	github.com/bytedance/gopkg v0.1.4 // indirect
+	github.com/bytedance/sonic v1.15.2 // indirect
+	github.com/bytedance/sonic/loader v0.5.1 // indirect
+	github.com/cloudwego/base64x v0.1.7 // indirect
+	github.com/gabriel-vasile/mimetype v1.4.13 // indirect
+	github.com/gin-contrib/sse v1.1.1 // indirect
+	github.com/go-playground/locales v0.14.1 // indirect
+	github.com/go-playground/universal-translator v0.18.1 // indirect
+	github.com/go-playground/validator/v10 v10.30.3 // indirect
+	github.com/goccy/go-json v0.10.6 // indirect
+	github.com/goccy/go-yaml v1.19.2 // indirect
+	github.com/gorilla/context v1.1.2 // indirect
+	github.com/gorilla/securecookie v1.1.2 // indirect
+	github.com/gorilla/sessions v1.4.0 // indirect
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/klauspost/cpuid/v2 v2.4.0 // indirect
+	github.com/leodido/go-urn v1.4.0 // indirect
+	github.com/mattn/go-isatty v0.0.23 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/pelletier/go-toml/v2 v2.4.3 // indirect
+	github.com/quic-go/qpack v0.6.0 // indirect
+	github.com/quic-go/quic-go v0.60.0 // indirect
+	github.com/twitchyliquid64/golang-asm v0.15.1 // indirect
+	github.com/ugorji/go/codec v1.3.1 // indirect
+	go.mongodb.org/mongo-driver/v2 v2.8.0 // indirect
+	golang.org/x/arch v0.29.0 // indirect
+	golang.org/x/net v0.57.0 // indirect
+	golang.org/x/sys v0.47.0 // indirect
+	golang.org/x/text v0.41.0 // indirect
+	google.golang.org/protobuf v1.36.11 // indirect
 )
@@ -1,18 +1,100 @@
-github.com/richardlehane/mscfb v1.0.7 h1:oeoiM0WE79vHwE8RpIYYvIAc8ajTH2mb6UZm55/+EB0=
-github.com/richardlehane/mscfb v1.0.7/go.mod h1:pe0+IUIc0AHh0+teNzBlJCtSyZdFOGgV4ZK9bsoV+Jo=
-github.com/richardlehane/msoleps v1.0.6 h1:9BvkpjvD+iUBalUY4esMwv6uBkfOip/Lzvd93jvR9gg=
-github.com/richardlehane/msoleps v1.0.6/go.mod h1:BWev5JBpU9Ko2WAgmZEuiz4/u3ZYTKbjLycmwiWUfWg=
-github.com/tiendc/go-deepcopy v1.7.2 h1:Ut2yYR7W9tWjTQitganoIue4UGxZwCcJy3orjrrIj44=
-github.com/tiendc/go-deepcopy v1.7.2/go.mod h1:4bKjNC2r7boYOkD2IOuZpYjmlDdzjbpTRyCx+goBCJQ=
-github.com/xuri/efp v0.0.1 h1:fws5Rv3myXyYni8uwj2qKjVaRP30PdjeYe2Y6FDsCL8=
-github.com/xuri/efp v0.0.1/go.mod h1:ybY/Jr0T0GTCnYjKqmdwxyxn2BQf2RcQIIvex5QldPI=
-github.com/xuri/excelize/v2 v2.11.0 h1:HxaEFl6sRN2+8J5a8HaKq+0M4FsjBGMnWWtjOCPSG88=
-github.com/xuri/excelize/v2 v2.11.0/go.mod h1:jxFLbzaIwGQ5ufFNvYfUOHqXhfPaNmP14KWfmNz2Uak=
-github.com/xuri/nfp v0.0.2-0.20250530014748-2ddeb826f9a9 h1:+C0TIdyyYmzadGaL/HBLbf3WdLgC29pgyhTjAT/0nuE=
-github.com/xuri/nfp v0.0.2-0.20250530014748-2ddeb826f9a9/go.mod h1:WwHg+CVyzlv/TX9xqBFXEZAuxOPxn2k1GNHwG41IIUQ=
-golang.org/x/crypto v0.53.0 h1:QZ4Muo8THX6CizN2vPPd5fBGHyogrdK9fG4wLPFUsto=
-golang.org/x/crypto v0.53.0/go.mod h1:DNLU434OwVakk9PzuwV8w62mAJpRJL3vsgcfp4Qnsio=
-golang.org/x/net v0.56.0 h1:Rw8j/hFzGvJUZwNBXnAtf5sVDVt+65SK2C7IxCxZt5o=
-golang.org/x/net v0.56.0/go.mod h1:D3Ku6r+V6JROoZK144D2XfMHFcMq/0zSfLelVTCFKec=
-golang.org/x/text v0.38.0 h1:sXmwo9DwP3OK9EZ7PqAdaooSGozfl/3a6/xJcbzPRhE=
-golang.org/x/text v0.38.0/go.mod h1:YXZt3QhHUKYT53r2lLKFIVi6Ao1jdzrTR/KQ09qyxF4=
+github.com/bytedance/gopkg v0.1.4 h1:oZnQwnX82KAIWb7033bEwtxvTqXcYMxDBaQxo5JJHWM=
+github.com/bytedance/gopkg v0.1.4/go.mod h1:v1zWfPm21Fb+OsyXN2VAHdL6TBb2L88anLQgdyje6R4=
+github.com/bytedance/sonic v1.15.2 h1:90H+rcF/FwLXwfB1cudOLq/je83n683Utf4Cbp0xHCo=
+github.com/bytedance/sonic v1.15.2/go.mod h1:mT2NbXunuaEbnZ+mRIX/vYqKISmgEuHFDI4UzmKx2SA=
+github.com/bytedance/sonic/loader v0.5.1 h1:Ygpfa9zwRCCKSlrp5bBP/b/Xzc3VxsAW+5NIYXrOOpI=
+github.com/bytedance/sonic/loader v0.5.1/go.mod h1:AR4NYCk5DdzZizZ5djGqQ92eEhCCcdf5x77udYiSJRo=
+github.com/cloudwego/base64x v0.1.7 h1:NppS+Fgzg5ovhn4NkUXaDT3x9jldgH5ToMCqzBSi2zI=
+github.com/cloudwego/base64x v0.1.7/go.mod h1:Cu1PV9zfrSf7ET2tIbWbbEy7jO7HHJ13q4X2SQ8aWYg=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/gabriel-vasile/mimetype v1.4.13 h1:46nXokslUBsAJE/wMsp5gtO500a4F3Nkz9Ufpk2AcUM=
+github.com/gabriel-vasile/mimetype v1.4.13/go.mod h1:d+9Oxyo1wTzWdyVUPMmXFvp4F9tea18J8ufA774AB3s=
+github.com/gin-contrib/sessions v1.1.2 h1:utWRqOHT/kbqxxqF/mtutV9wfGLi1+uu5YuvWUhj/Ow=
+github.com/gin-contrib/sessions v1.1.2/go.mod h1:qRxYwA/TYJw0wv28oFzs4gY/8G8z69id862SNgX9Gmw=
+github.com/gin-contrib/sse v1.1.1 h1:uGYpNwTacv5R68bSGMapo62iLTRa9l5zxGCps4hK6ko=
+github.com/gin-contrib/sse v1.1.1/go.mod h1:QXzuVkA0YO7o/gun03UI1Q+FTI8ZV/n5t03kIQAI89s=
+github.com/gin-gonic/gin v1.12.0 h1:b3YAbrZtnf8N//yjKeU2+MQsh2mY5htkZidOM7O0wG8=
+github.com/gin-gonic/gin v1.12.0/go.mod h1:VxccKfsSllpKshkBWgVgRniFFAzFb9csfngsqANjnLc=
+github.com/go-playground/assert/v2 v2.2.0 h1:JvknZsQTYeFEAhQwI4qEt9cyV5ONwRHC+lYKSsYSR8s=
+github.com/go-playground/assert/v2 v2.2.0/go.mod h1:VDjEfimB/XKnb+ZQfWdccd7VUvScMdVu0Titje2rxJ4=
+github.com/go-playground/locales v0.14.1 h1:EWaQ/wswjilfKLTECiXz7Rh+3BjFhfDFKv/oXslEjJA=
+github.com/go-playground/locales v0.14.1/go.mod h1:hxrqLVvrK65+Rwrd5Fc6F2O76J/NuW9t0sjnWqG1slY=
+github.com/go-playground/universal-translator v0.18.1 h1:Bcnm0ZwsGyWbCzImXv+pAJnYK9S473LQFuzCbDbfSFY=
+github.com/go-playground/universal-translator v0.18.1/go.mod h1:xekY+UJKNuX9WP91TpwSH2VMlDf28Uj24BCp08ZFTUY=
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+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
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@@ -0,0 +1,149 @@
+package crypto
+
+import (
+	"errors"
+	"testing"
+	"time"
+
+	"golang.org/x/crypto/bcrypt"
+)
+
+var (
+	ErrInvalidPassword = errors.New("invalid password")
+	ErrInvalidHash     = errors.New("invalid password hash")
+)
+
+type Hasher struct {
+	cost int // cost 可以理解成 bcrypt 的“计算难度”参数,cost 越高，计算 bcrypt hash 就越慢，攻击者暴力破解密码也越贵
+}
+
+func NewHasher(cost int) (*Hasher, error) {
+	if cost < bcrypt.MinCost || cost > bcrypt.MaxCost {
+		return nil, errors.New("invalid bcrypt cost")
+	}
+
+	return &Hasher{
+		cost: cost,
+	}, nil
+}
+
+// Hash 用于注册、重置密码、修改密码。
+func (h *Hasher) Hash(password string) (string, error) {
+	if len(password) == 0 {
+		return "", ErrInvalidPassword
+	}
+
+	// bcrypt 只使用密码前 72 bytes。
+	// 生产环境建议显式拒绝，而不是静默截断。
+	if len([]byte(password)) > 72 {
+		return "", ErrInvalidPassword
+	}
+
+	hash, err := bcrypt.GenerateFromPassword(
+		[]byte(password),
+		h.cost,
+	)
+	if err != nil {
+		return "", err
+	}
+
+	return string(hash), nil
+}
+
+// Verify 用于登录时验证密码。
+func (h *Hasher) Verify(password, encodedHash string) (bool, error) {
+	if len(password) == 0 || len([]byte(password)) > 72 {
+		return false, ErrInvalidPassword
+	}
+
+	if encodedHash == "" {
+		return false, ErrInvalidHash
+	}
+
+	err := bcrypt.CompareHashAndPassword(
+		[]byte(encodedHash),
+		[]byte(password),
+	)
+
+	switch {
+	case err == nil:
+		return true, nil
+
+	case errors.Is(err, bcrypt.ErrMismatchedHashAndPassword):
+		return false, nil
+
+	default:
+		// 例如数据库里的 hash 已损坏或格式不合法。
+		return false, ErrInvalidHash
+	}
+}
+
+// NeedsRehash 判断数据库中的 hash 是否使用了较旧的 cost。
+func (h *Hasher) NeedsRehash(encodedHash string) bool {
+	cost, err := bcrypt.Cost([]byte(encodedHash))
+	if err != nil {
+		return true
+	}
+
+	return cost != h.cost
+}
+
+func TestBcrypt(t *testing.T) {
+	oldHasher, err := NewHasher(10)
+	if err != nil {
+		t.Fatal(err)
+	}
+	newHasher, err := NewHasher(12)
+	if err != nil {
+		t.Fatal(err)
+	}
+	password := "password"
+	oldHash, err := oldHasher.Hash(password)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Log(oldHash)
+	newHash, err := newHasher.Hash(password)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Log(newHash)
+	err = bcrypt.CompareHashAndPassword([]byte(oldHash), []byte(password))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+}
+
+func TestHashPassword(t *testing.T) {
+	hasher, err := NewHasher(12)
+	if err != nil {
+		t.Fatal(err)
+	}
+	password := "password"
+	hash, err := hasher.Hash(password)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Log(hash)
+	if ok, err := hasher.Verify(password, hash); err != nil || !ok {
+		t.Fatal("verify failed")
+	}
+	if ok := hasher.NeedsRehash(hash); !ok {
+		t.Fatal("needs rehash failed")
+	}
+
+}
+
+func TestGenerateTime(t *testing.T) {
+	start := time.Now()
+
+	_, err := bcrypt.GenerateFromPassword(
+		[]byte("TestPassword123!"),
+		14,
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Log(time.Since(start), err)
+}
@@ -0,0 +1,68 @@
+package main
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	// 引入两个包进行对比
+	jsonV1 "encoding/json"
+	jsonV2 "encoding/json/v2"
+)
+
+func TestV2Null(t *testing.T) {
+	type Product struct {
+		Name string   `json:"name"`
+		Tags []string `json:"tags"`
+	}
+	p := Product{
+		Name: "product1",
+	}
+	data1, _ := jsonV1.Marshal(p)
+	data2, _ := jsonV2.Marshal(p)
+	t.Log(string(data1))
+	t.Log(string(data2))
+}
+
+func TestOmitZeroVsEmpty(t *testing.T) {
+	// ===== V1 结构体：使用 omitempty =====
+	type EventV1 struct {
+		Title     string    `json:"title"`
+		CreatedAt time.Time `json:"created_at,omitempty"` // ⚠️ omitempty 对 time.Time 无效
+	}
+
+	// ===== V2 结构体：使用 omitzero =====
+	type EventV2 struct {
+		Title     string    `json:"title"`
+		CreatedAt time.Time `json:"created_at,omitzero"` // ✅ omitzero 能识别 IsZero()
+	}
+	// 都不给 CreatedAt 赋值，保持 Go 的零值 time.Time{}
+
+	// 1. 测试 v1 + omitempty
+	e1 := EventV1{Title: "Go Meetup"}
+	data1, _ := jsonV1.Marshal(e1)
+	fmt.Println("v1 + omitempty 输出:", string(data1))
+
+	// 2. 测试 v2 + omitzero
+	e2 := EventV2{Title: "Go Meetup"}
+	data2, _ := jsonV2.Marshal(e2)
+	fmt.Println("v2 + omitzero  输出:", string(data2))
+}
+
+func TestMultiStyle(t *testing.T) {
+	type MultiStyleUser struct {
+		// 1. 严格匹配：JSON key 必须精确是 "user_id"
+		ID string `json:"user_id,case:strict"`
+
+		// 2. 忽略大小写：JSON key 是 "Name"、"NAME"、"name" 都能成功赋值
+		Name string `json:"name,case:ignore"`
+	}
+	// 假设第三方传来的 JSON 风格混杂
+	jsonData := []byte(`{
+    "user_id": "1001",
+    "NAME": "Gopher"
+}`)
+	var m MultiStyleUser
+	jsonV2.Unmarshal(jsonData, &m)
+	t.Log(m)
+}
@@ -1,6 +1,7 @@
 package testing

 import (
+	"fmt"
 	"sort"
 	"testing"
 	"time"
@@ -46,3 +47,63 @@ func TestChannel(t *testing.T) {
 	var c chan bool // 一个零值nil通道
 	<-c             // 永久阻塞在此
 }
+
+func TestFeature1(t *testing.T) {
+	type Person struct {
+		Sex  string
+		Name string
+	}
+	type Student struct {
+		StudentID int
+		Person
+	}
+
+	s1 := Student{
+		StudentID: 1,
+		Sex:       "male",
+		Name:      "张三",
+	}
+	t.Log(s1)
+}
+
+func TestFeature2(t *testing.T) {
+	// Go 1.27 之前：必须手动写出类型实参 [int]，否则编译报错
+	fn1 := IntToString(FormatToString[int])
+	fn2 := IntToString(FormatToString)
+
+	oldFormat := []IntToString{FormatToString[int]}
+	newFormat := []IntToString{FormatToString}
+
+	t.Log(fn1(1))
+	t.Log(fn2(2))
+	for i, fn := range oldFormat {
+		t.Log(fn(i))
+	}
+	for i, fn := range newFormat {
+		t.Log(fn(i))
+	}
+
+}
+
+// 一个泛型格式化函数
+func FormatToString[T any](v T) string {
+	return fmt.Sprintf("value: %v", v)
+}
+
+// 具名函数类型：接收一个 int，返回 string
+type IntToString func(int) string
+
+func TestSort(t *testing.T) {
+	slice := []int{8, 2, 4, 4}
+	Sort1(slice)
+	t.Log(slice)
+}
+func Sort1(slice []int) {
+	for i := 0; i < len(slice)-1; i++ {
+		for j := 0; j < len(slice)-1-i; j++ {
+			if slice[j] > slice[j+1] {
+				slice[j], slice[j+1] = slice[j+1], slice[j]
+			}
+		}
+	}
+}