之前，已经讲过很多Golang的东西，比如基础语法，mysql的使用，redis的使用等等，感兴趣的可以看看以前的文章，https://www.cnblogs.com/zhangweizhong/category/1275863.html，

今天就用从头写一个完整的go的示例项目吧。

本项目完全使用原生开发，没有使用任何WEB框架和ORM。虽然大家对mvc 呀，三层架构已经很了解了。但是，我还是想从头写一个完整的示例项目。这样大家有一个更深刻的了解，这样以后介绍web框架，orm框架的时候，学习起来应该会简单一点。

项目架构

下图这种架构模式相信大家应该十分清楚

Controller组合封装

Controller"基类"封装

package frameworktype Controller struct {   Data interface{}}

UserController定义了用户注册，登录和查询等简单的三个接口

package controllerimport (   "net/http"   "micro-cloud/service"   "micro-cloud/utils"   "micro-cloud/framework")/** * r.PostFormValue  : 可以解析 Post/PUT Content-Type=application/x-www-form-urlencoded 或 Content-Type=multipart/form-data */type UserConterller struct {}var userService = new(service.UserService)func (p *UserConterller) Router(router *framework.RouterHandler) {   router.Router("/register", p.register)   router.Router("/login", p.login)   router.Router("/findAll", p.findAll)}//POST Content-Type=application/x-www-form-urlencodedfunc (p *UserConterller) register(w http.ResponseWriter, r *http.Request) {   username := r.PostFormValue("username")   password := r.PostFormValue("password")   if utils.Empty(username) || utils.Empty(password) {      microcloud.ResultFail(w, "username or password can not be empty")      return   }   id := userService.Insert(username, password)   if id <= 0 {      microcloud.ResultFail(w, "register fail")      return   }   microcloud.ResultOk(w, "register success")}//POST Content-Type=application/x-www-form-urlencodedfunc (p *UserConterller) login(w http.ResponseWriter, r *http.Request) {   username := r.PostFormValue("username")   password := r.PostFormValue("password")   if utils.Empty(username) || utils.Empty(password) {      microcloud.ResultFail(w, "username or password can not be empty")      return   }   users := userService.SelectUserByName(username)   if len(users) == 0 {      microcloud.ResultFail(w, "user does not exist")      return   }   if users[0].Password != password {      microcloud.ResultFail(w, "password error")      return   }   microcloud.ResultOk(w, "login success")}// GET/POSTfunc (p *UserConterller) findAll(w http.ResponseWriter, r *http.Request) {   users := userService.SelectAllUser()   framework.ResultJsonOk(w, users)}

数据访问层

package daoimport (    "micro-cloud/model"    "fmt"    )type UserDao struct {}func (p *UserDao) Insert(user *model.User) int64 {    result, err := framework.DB.Exec("INSERT INTO user(`username`,`password`,`create_time`) value(?,?,?)", user.Username, user.Password, user.CreateTime)    if err != nil {        fmt.Println("Insert error")        return 0    }    id, err := result.LastInsertId()    if err != nil {        fmt.Println("Insert error")        return 0    }    return id}func (p *UserDao) SelectUserByName(username string) []model.User {    rows, err := framework.DB.Query("SELECT * FROM user WHERE username = ?", username)    if err != nil {        fmt.Println("selectuserbyname error")        return nil    }    var users []model.User    for rows.Next() {        var user model.User        err := rows.Scan(&user.ID, &user.Username, &user.Password, &user.CreateTime)        if err != nil {            fmt.Println("selectuserbyname error")            continue        }        users = append(users, user)    }    rows.Close()    return users}func (p *UserDao) SelectAllUser() []model.User {    rows, err := framework.DB.Query("SELECT * FROM user")    if err != nil {        fmt.Println("SelectAllUser error")        return nil    }    var users []model.User    for rows.Next() {        var user model.User        err := rows.Scan(&user.ID, &user.Username, &user.Password, &user.CreateTime)        if err != nil {            fmt.Println("SelectAllUser error")            continue        }        users = append(users, user)    }    rows.Close()    return users}

实体层

package modelimport "time"type User struct {    ID         uint      `json:"id"`    Username   string    `json:"username"`    Password   string    `json:"-"`    CreateTime time.Time `json:"create_time"`}

database

数据库操作类的实现

package microcloudimport (    "database/sql"    "log"    "strings"    _ "github.com/go-sql-driver/mysql")//数据库的配置const (    username   = "admin"    password   = "123456"    ip         = "10.2.1.5"    port       = "3306"    dbName     = "microcloud"    driverName = "mysql")//DB数据库连接池var DB *sql.DBfunc InitDB() {    //构建连接："用户名:密码@tcp(IP:端口)/数据库?charset=uft8"    //注意：要想解析time.Time类型，必须要设置parseTime=True    path := strings.Join([]string{username, ":", password, "@tcp(", ip, ":", port, ")/", dbName, "?charset=utf8&parseTime=True&loc=Local"}, "")    //打开数据库，前者是驱动名，所以要导入:_"github.com/go-sql-driver/mysql"    DB, _ = sql.Open(driverName, path)    //设置数据库最大连接数    DB.SetConnMaxLifetime(100)    //设置数据库最大闲置连接数    DB.SetMaxIdleConns(10)    //验证连接    if err := DB.Ping(); err != nil {        log.Panic(err)    }    log.Println("database connect success")}func CreateTable() {    userTable := "CREATE TABLE IF NOT EXISTS `user`(" +        "`id` INT UNSIGNED AUTO_INCREMENT," +        "`username` VARCHAR(20) NOT NULL," +        "`password` VARCHAR(40) NOT NULL," +        "`create_time` DATETIME," +        "PRIMARY KEY ( `id` )" +        ")ENGINE=InnoDB DEFAULT CHARSET=utf8;"    _, err := DB.Exec(userTable)    if err != nil {        log.Panic(err)    }}

http

http server的实现

server := &http.Server{        Addr:        ":8215",        Handler:     microcloud.Router,        ReadTimeout: 5 * time.Second,    }    RegiterRouter(microcloud.Router)    err := server.ListenAndServe()    if err != nil {        log.Panic(err)    }

Router

路由处理的实现，其实也就是一个转发的功能

type RouterHandler struct {}var mux = make(map[string]func(http.ResponseWriter,*http.Request))func (p *RouterHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {    fmt.Println(r.URL.Path)    if fun, ok := mux[r.URL.Path]; ok {        fun(w, r)        return    }    //静态资源    if strings.HasPrefix(r.URL.Path,constant.STATIC_BAES_PATH){        if fun, ok := mux[constant.STATIC_BAES_PATH]; ok {            fun(w, r)            return        }    }    http.Error(w, "error URL:"+r.URL.String(), http.StatusBadRequest)}func (p *RouterHandler) Router(relativePath string, handler func(http.ResponseWriter, *http.Request)) {    mux[relativePath] = handler}

演示

执行 go run main.go 之后，打开Postman，调相关的接口

以下就是访问API的请求与响应

/findAll 接口

/register 接口

最后

以上，用Go语言实现webapi 的例子，已经介绍完了，虽然比较简单，session，权限验证等都没有加。但是最主要的功能已经讲完了，感兴趣的可以从头编写下相关的代码。

完整例子下载：microcloud.rar