diff --git a/book/v3/ README.md b/book/v3/ README.md
index 76f1166..4f2dec6 100644
--- a/book/v3/ README.md	
+++ b/book/v3/ README.md	
@@ -1 +1,3 @@
-# mvc 功能分层架构
\ No newline at end of file
+# mvc 功能分层架构
+
+PO, 数据库对象
\ No newline at end of file
diff --git a/book/v3/config/README.md b/book/v3/config/README.md
new file mode 100644
index 0000000..f3d7d23
--- /dev/null
+++ b/book/v3/config/README.md
@@ -0,0 +1,20 @@
+# 程序的配置管理
+
+
+## 配置的加载
+```go
+// 用于加载配置
+config.LoadConfigFromYaml(yamlConfigFilePath)
+```
+
+## 程序内部如何使用配置
+```go
+// Get Config --> ConfigObject
+config.C().MySQL.Host
+// config.ConfigObjectInstance
+```
+
+## 为你的包添加单元测试
+
+如何验证我们这个包的 业务逻辑是正确
+
diff --git a/book/v3/config/config.go b/book/v3/config/config.go
new file mode 100644
index 0000000..12981aa
--- /dev/null
+++ b/book/v3/config/config.go
@@ -0,0 +1,86 @@
+package config
+
+import (
+	"fmt"
+	"sync"
+
+	"122.51.31.227/go-course/go18/book/v3/models"
+	"github.com/infraboard/mcube/v2/tools/pretty"
+	"gorm.io/driver/mysql"
+	"gorm.io/gorm"
+)
+
+func Default() *Config {
+	return &Config{
+		Application: &application{
+			Host: "127.0.0.1",
+			Port: 8080,
+		},
+		MySQL: &mySQL{
+			Host:     "127.0.0.1",
+			Port:     3306,
+			DB:       "test",
+			Username: "root",
+			Password: "123456",
+			Debug:    true,
+		},
+	}
+}
+
+// 这歌对象就是程序配置
+// yaml, toml
+type Config struct {
+	Application *application `toml:"app" yaml:"app" json:"app"`
+	MySQL       *mySQL       `toml:"mysql" yaml:"mysql" json:"mysql"`
+}
+
+func (c *Config) String() string {
+	return pretty.ToJSON(c)
+}
+
+// 应用服务
+type application struct {
+	Host string `toml:"host" yaml:"host" json:"host" env:"HOST"`
+	Port int    `toml:"port" yaml:"port" json:"port" env:"PORT"`
+}
+
+// db对象也是一个单列模式
+type mySQL struct {
+	Host     string `json:"host" yaml:"host" toml:"host" env:"DATASOURCE_HOST"`
+	Port     int    `json:"port" yaml:"port" toml:"port" env:"DATASOURCE_PORT"`
+	DB       string `json:"database" yaml:"database" toml:"database" env:"DATASOURCE_DB"`
+	Username string `json:"username" yaml:"username" toml:"username" env:"DATASOURCE_USERNAME"`
+	Password string `json:"password" yaml:"password" toml:"password" env:"DATASOURCE_PASSWORD"`
+	Debug    bool   `json:"debug" yaml:"debug" toml:"debug" env:"DATASOURCE_DEBUG"`
+
+	// gorm db对象, 只需要有1个,不运行重复生成
+	db *gorm.DB
+	// 互斥锁
+	lock sync.Mutex
+}
+
+func (m *mySQL) GetDB() *gorm.DB {
+	m.lock.Lock()
+	defer m.lock.Unlock()
+
+	if m.db == nil {
+		// 初始化数据库
+		// dsn := "root:123456@tcp(127.0.0.1:3306)/test?charset=utf8mb4&parseTime=True&loc=Local"
+		dsn := fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?charset=utf8mb4&parseTime=True&loc=Local",
+			m.Username,
+			m.Password,
+			m.Host,
+			m.Port,
+			m.DB,
+		)
+
+		db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{})
+		if err != nil {
+			panic("failed to connect database")
+		}
+		db.AutoMigrate(&models.Book{}) // 自动迁移
+		m.db = db
+	}
+
+	return m.db
+}
diff --git a/book/v3/config/config_test.go b/book/v3/config/config_test.go
new file mode 100644
index 0000000..8d36673
--- /dev/null
+++ b/book/v3/config/config_test.go
@@ -0,0 +1,26 @@
+package config_test
+
+import (
+	"fmt"
+	"os"
+	"testing"
+
+	"122.51.31.227/go-course/go18/book/v3/config"
+)
+
+func TestLoadConfigFromYaml(t *testing.T) {
+	err := config.LoadConfigFromYaml(fmt.Sprintf("%s/book/v2/application.yaml", os.Getenv("workspaceFolder")))
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Log(config.C())
+}
+
+func TestLoadConfigFromEnv(t *testing.T) {
+	os.Setenv("DATASOURCE_HOST", "localhost")
+	err := config.LoadConfigFromEnv()
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Log(config.C())
+}
diff --git a/book/v3/config/load.go b/book/v3/config/load.go
new file mode 100644
index 0000000..8edcf84
--- /dev/null
+++ b/book/v3/config/load.go
@@ -0,0 +1,52 @@
+package config
+
+import (
+	"os"
+
+	"github.com/caarlos0/env/v6"
+	"gopkg.in/yaml.v3"
+	"gorm.io/gorm"
+)
+
+// 配置加载
+// file/env/...  --->  Config
+// 全局一份
+
+// config 全局变量, 通过函数对我提供访问
+var config *Config
+
+func C() *Config {
+	// 没有配置文件怎么办?
+	// 默认配置, 方便开发者
+	if config == nil {
+		config = Default()
+	}
+
+	return config
+}
+
+func DB() *gorm.DB {
+	return C().MySQL.GetDB()
+}
+
+// 加载配置 把外部配置读到 config全局变量里面来
+// yaml 文件yaml --> conf
+func LoadConfigFromYaml(configPath string) error {
+	content, err := os.ReadFile(configPath)
+	if err != nil {
+		return err
+	}
+
+	// 默认值
+	config = C()
+	return yaml.Unmarshal(content, config)
+}
+
+// 从环境变量读取配置
+// "github.com/caarlos0/env/v6"
+func LoadConfigFromEnv() error {
+	config = C()
+	// MYSQL_DB <---> DB
+	// config.MySQL.DB = os.Getenv("MYSQL_DB")
+	return env.Parse(config)
+}
diff --git a/book/v3/controllers/README.md b/book/v3/controllers/README.md
new file mode 100644
index 0000000..1b8ac10
--- /dev/null
+++ b/book/v3/controllers/README.md
@@ -0,0 +1,3 @@
+# 控制器
+
+业务处理
diff --git a/book/v3/handlers/README.md b/book/v3/handlers/README.md
new file mode 100644
index 0000000..4afc648
--- /dev/null
+++ b/book/v3/handlers/README.md
@@ -0,0 +1,3 @@
+# api handlers
+
+HTTP RESTful 接口
\ No newline at end of file
diff --git a/book/v3/handlers/book.go b/book/v3/handlers/book.go
new file mode 100644
index 0000000..ecbf636
--- /dev/null
+++ b/book/v3/handlers/book.go
@@ -0,0 +1,180 @@
+package handlers
+
+import (
+	"net/http"
+	"strconv"
+
+	"122.51.31.227/go-course/go18/book/v3/config"
+	"122.51.31.227/go-course/go18/book/v3/models"
+	"github.com/gin-gonic/gin"
+)
+
+var Book = &BookApiHandler{}
+
+type BookApiHandler struct {
+}
+
+func (h *BookApiHandler) Registry(r gin.IRouter) {
+	// Book Restful API
+	// List of books
+	r.GET("/api/books", h.listBook)
+	// Create new book
+	// Body: HTTP Entity
+	r.POST("/api/books", h.createBook)
+	// Get book by book number
+	r.GET("/api/books/:bn", h.getBook)
+	// Update book
+	r.PUT("/api/books/:bn", h.updateBook)
+	// Delete book
+	r.DELETE("/api/books/:bn", h.deleteBook)
+}
+
+// 实现后端分页的
+func (h *BookApiHandler) listBook(ctx *gin.Context) {
+	set := &models.BookSet{}
+
+	// List<*Book>
+	//  *Set[T]
+	// types.New[*Book]()
+
+	// 给默认值
+	pn, ps := 1, 20
+	// /api/books?page_number=1&page_size=20
+	pageNumber := ctx.Query("page_number")
+	if pageNumber != "" {
+		pnInt, err := strconv.ParseInt(pageNumber, 10, 64)
+		if err != nil {
+			ctx.JSON(400, gin.H{"code": 400, "message": err.Error()})
+			return
+		}
+		pn = int(pnInt)
+	}
+
+	pageSize := ctx.Query("page_size")
+	if pageSize != "" {
+		psInt, err := strconv.ParseInt(pageSize, 10, 64)
+		if err != nil {
+			ctx.JSON(400, gin.H{"code": 400, "message": err.Error()})
+			return
+		}
+		ps = int(psInt)
+	}
+
+	query := config.DB().Model(&models.Book{})
+	// 关键字过滤
+	kws := ctx.Query("keywords")
+	if kws != "" {
+		// where title like %kws%
+		query = query.Where("title LIKE ?", "%"+kws+"%")
+	}
+
+	// 其他过滤条件
+
+	// select * from books
+	// 通过sql的offset limte 来实现分页
+	//  offset (page_number -1) * page_size, limit page_size
+	// 2  offset 20, 20
+	// 3  offset 40, 20
+	// 4  offset 3 * 20, 20
+	offset := (pn - 1) * ps
+	if err := query.Count(&set.Total).Offset(int(offset)).Limit(int(ps)).Find(&set.Items).Error; err != nil {
+		ctx.JSON(500, gin.H{"code": 500, "message": err.Error()})
+		return
+	}
+
+	// 获取总数, 总共多少个, 总共有多少页
+	ctx.JSON(200, set)
+}
+
+func (h *BookApiHandler) createBook(ctx *gin.Context) {
+	// payload, err := io.ReadAll(ctx.Request.Body)
+	// if err != nil {
+	// 	ctx.JSON(400, gin.H{"code": 400, "message": err.Error()})
+	// 	return
+	// }
+	// defer ctx.Request.Body.Close()
+	// // {"title": "Go语言"}
+
+	// c.Request.Header.Get(key)
+	// ctx.GetHeader("Authincation")
+
+	// new(Book)
+	bookSpecInstance := &models.BookSpec{}
+	// // 通过JSON的 Struct Tag
+	// // bookInstance.Title =  "Go语言"
+	// if err := json.Unmarshal(payload, bookInstance); err != nil {
+	// 	ctx.JSON(400, gin.H{"code": 400, "message": err.Error()})
+	// 	return
+	// }
+	// 获取到bookInstance
+	// 参数是不是为空
+	if err := ctx.BindJSON(bookSpecInstance); err != nil {
+		ctx.JSON(400, gin.H{"code": 400, "message": err.Error()})
+		return
+	}
+
+	// 有没有能够检查某个字段是否是必须填
+	// Gin 集成 validator这个库, 通过 struct tag validate 来表示这个字段是否允许为空
+	// validate:"required"
+	// 在数据Bind的时候，这个逻辑会自动运行
+	// if bookSpecInstance.Author == "" {
+	// 	ctx.JSON(400, gin.H{"code": 400, "message": err.Error()})
+	// 	return
+	// }
+
+	bookInstance := &models.Book{BookSpec: *bookSpecInstance}
+
+	// 数据入库(Grom), 补充自增Id的值
+	if err := config.DB().Save(bookInstance).Error; err != nil {
+		ctx.JSON(400, gin.H{"code": 500, "message": err.Error()})
+		return
+	}
+
+	// 返回响应
+	ctx.JSON(http.StatusCreated, bookInstance)
+}
+
+func (h *BookApiHandler) getBook(ctx *gin.Context) {
+	bookInstance := &models.Book{}
+	// 需要从数据库中获取一个对象
+	if err := config.DB().Where("id = ?", ctx.Param("bn")).Take(bookInstance).Error; err != nil {
+		ctx.JSON(400, gin.H{"code": 500, "message": err.Error()})
+		return
+	}
+
+	ctx.JSON(200, bookInstance)
+}
+
+func (h *BookApiHandler) updateBook(ctx *gin.Context) {
+	bnStr := ctx.Param("bn")
+	bn, err := strconv.ParseInt(bnStr, 10, 64)
+	if err != nil {
+		ctx.JSON(400, gin.H{"code": 400, "message": err.Error()})
+		return
+	}
+
+	// 读取body里面的参数
+	bookInstance := &models.Book{
+		Id: uint(bn),
+	}
+	// 获取到bookInstance
+	if err := ctx.BindJSON(&bookInstance.BookSpec); err != nil {
+		ctx.JSON(400, gin.H{"code": 400, "message": err.Error()})
+		return
+	}
+
+	if err := config.DB().Where("id = ?", bookInstance.Id).Updates(bookInstance).Error; err != nil {
+		ctx.JSON(400, gin.H{"code": 400, "message": err.Error()})
+		return
+	}
+
+	ctx.JSON(200, bookInstance)
+}
+
+func (h *BookApiHandler) deleteBook(ctx *gin.Context) {
+	if err := config.DB().Where("id = ?", ctx.Param("bn")).Delete(&models.Book{}).Error; err != nil {
+		ctx.JSON(400, gin.H{"code": 400, "message": err.Error()})
+		return
+	}
+	ctx.JSON(http.StatusNoContent, "ok")
+}
diff --git a/book/v3/main.go b/book/v3/main.go
new file mode 100644
index 0000000..0bab28f
--- /dev/null
+++ b/book/v3/main.go
@@ -0,0 +1,20 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"122.51.31.227/go-course/go18/book/v3/handlers"
+	"github.com/gin-gonic/gin"
+)
+
+func main() {
+	server := gin.Default()
+
+	handlers.Book.Registry(server)
+
+	if err := server.Run(":8080"); err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+}
diff --git a/book/v3/models/README.md b/book/v3/models/README.md
new file mode 100644
index 0000000..0543d93
--- /dev/null
+++ b/book/v3/models/README.md
@@ -0,0 +1 @@
+# 数据模型
\ No newline at end of file
diff --git a/book/v3/models/book.go b/book/v3/models/book.go
new file mode 100644
index 0000000..4ccc402
--- /dev/null
+++ b/book/v3/models/book.go
@@ -0,0 +1,30 @@
+package models
+
+type BookSet struct {
+	// 总共多少个
+	Total int64 `json:"total"`
+	// book清单
+	Items []*Book `json:"items"`
+}
+
+type Book struct {
+	// 对象Id
+	Id uint `json:"id" gorm:"primaryKey;column:id"`
+
+	BookSpec
+}
+
+type BookSpec struct {
+	// type 用于要使用gorm 来自动创建和更新表的时候 才需要定义
+	Title  string  `json:"title"  gorm:"column:title;type:varchar(200)" validate:"required"`
+	Author string  `json:"author"  gorm:"column:author;type:varchar(200);index" validate:"required"`
+	Price  float64 `json:"price"  gorm:"column:price" validate:"required"`
+	// bool false
+	// nil 是零值, false
+	IsSale *bool `json:"is_sale"  gorm:"column:is_sale"`
+}
+
+// books
+func (b *Book) TableName() string {
+	return "books"
+}