学习Go语言之简易ORM框架

抽象工厂模式常用于程序适配多种数据库，以达到开放扩展关闭修改的原则。

首先需要有一个思想就是数据库表结构都是固定，但是每种数据库语言存在差异性，因此使用接口规范功能，各种数据库有自己不同的语言实现，业务中也是使用接口操作，运行时根据配置实例化各种数据库实现。好处是增加新的数据库时，只需要用新的数据库语言实现即可，不用修改原来的代码。部署程序时，只需要修改配置即可适配不同的数据库。

一，数据模型（Model层）

myProject/MyORM/Model/User.go

 package Model

 type User struct {
     Id        int
     UID       string
     LoginName string
     PassWord  string
 }

 func (t *User) TableName() string {
     return "User"
 }

myProject/MyORM/Model/Product.go

 package Model

 type Product struct {
     Id    int
     UID   string
     Name  string
     Price float64
 }

 func (t *Product) TableName() string {
     return "Product"
 }

二，接口定义（Interface层）

myProject/MyORM/Data/IUser.go

 package Data

 import (
     "myProject/MyORM/Model"
 )

 type IUser interface {
     Add(entity *Model.User) bool
     Edit(entity *Model.User) Model.User
 }

myProject/MyORM/Data/IProduct.go

 package Data

 import (
     "myProject/MyORM/Model"
 )

 type IProduct interface {
     Add(entity *Model.Product) bool
     Edit(entity *Model.Product) Model.Product
 }

myProject/MyORM/Data/IProvider.go

♥ 抽象工厂接口

 package Data

 type IProvider interface {
     GetUser() IUser
     GetProduct() IProduct
 }

三，接口实现（DAL层）

♣ 注意：Go语言的接口实现是隐式的，无须让实现接口的类型写出实现了哪些接口。这个设计被称为非侵入式设计。在类型中添加与接口签名一致的方法就可以实现该方法。

1.SQL实现

myProject/MyORM/SqlData/SqlUser.go

 package SqlData

 import (
     "fmt"
     "myProject/MyORM/Model"
 )

 type SqlUser struct {
 }

 func (p *SqlUser) Add(entity *Model.User) bool {
     fmt.Println("sql执行UserAdd")
     return true
 }

 func (p *SqlUser) Edit(entity *Model.User) Model.User {
     fmt.Println("sql执行UserEdit")
     return *entity
 }

myProject/MyORM/SqlData/SqlProduct.go

 package SqlData

 import (
     "fmt"
     "myProject/MyORM/Model"
 )

 type SqlProduct struct {
 }

 func (p *SqlProduct) Add(entity *Model.Product) bool {
     fmt.Println("sql执行ProductAdd")
     return true
 }

 func (p *SqlProduct) Edit(entity *Model.Product) Model.Product {
     fmt.Println("sql执行ProductEdit")
     return *entity
 }

myProject/MyORM/SqlData/SqlProvider.go

♥ SQL工厂实现

 package SqlData

 import (
     "myProject/MyORM/Data"
 )

 type SqlProvider struct {
 }

 func (p *SqlProvider) GetUser() Data.IUser {
     return new(SqlUser)
 }

 func (p *SqlProvider) GetProduct() Data.IProduct {
     return new(SqlProduct)
 }

2.Mysql实现

myProject/MyORM/MysqlData/MysqlUser.go

 package MysqlData

 import (
     "fmt"
     "myProject/MyORM/Model"
 )

 type MysqlUser struct {
 }

 func (p *MysqlUser) Add(entity *Model.User) bool {
     fmt.Println("mysql执行UserAdd")
     return true
 }

 func (p *MysqlUser) Edit(entity *Model.User) Model.User {
     fmt.Println("mysql执行UserEdit")
     return *entity
 }

myProject/MyORM/MysqlData/MysqlProduct.go

 package MysqlData

 import (
     "fmt"
     "myProject/MyORM/Model"
 )

 type MysqlProduct struct {
 }

 func (p *MysqlProduct) Add(entity *Model.Product) bool {
     fmt.Println("mysql执行ProductAdd")
     return true
 }

 func (p *MysqlProduct) Edit(entity *Model.Product) Model.Product {
     fmt.Println("mysql执行ProductEdit")
     return *entity
 }

myProject/MyORM/MysqlData/MysqlProvider.go

♥ MYSQL工厂实现

 package MysqlData

 import (
     "myProject/MyORM/Data"
 )

 type MysqlProvider struct {
 }

 func (p *MysqlProvider) GetUser() Data.IUser {
     return new(MysqlUser)
 }

 func (p *MysqlProvider) GetProduct() Data.IProduct {
     return new(MysqlProduct)
 }

三，业务逻辑（BLL层）

myProject/MyORM/Service/Factory.go

 package Service

 import (
     "myProject/MyORM/Data"
     "myProject/MyORM/MysqlData"
     "myProject/MyORM/SqlData"
 )
 // 设置配置
 const db = "sql"

 // 简单工厂方法，根据配置加载不同的实现库
 func Provider() Data.IProvider {
     switch db {
     case "sql":
         return new(SqlData.SqlProvider)
     case "mysql":
         return new(MysqlData.MysqlProvider)
     default:
         panic("无法映射配置的数据库")
     }
 }

myProject/MyORM/Service/UserService.go

 package Service

 import (
     "myProject/MyORM/Data"
     "myProject/MyORM/Model"
 )

 type UserService struct {
 }

 var user Data.IUser

 func init() {
     user = Provider().GetUser()
 }

 func (u *UserService) Add(entity *Model.User) bool {
     return user.Add(entity)
 }

 func (u *UserService) Update(entity *Model.User) Model.User {
     return user.Edit(entity)
 }

myProject/MyORM/Service/ProductService.go

 package Service

 import (
     "myProject/MyORM/Data"
     "myProject/MyORM/Model"
 )

 type ProductService struct {
 }

 var product Data.IProduct

 func init() {
     product = Provider().GetProduct()
 }

 func (p *ProductService) Add(entity *Model.Product) bool {
     return product.Add(entity)
 }

 func (p *ProductService) Update(entity *Model.Product) Model.Product {
     return product.Edit(entity)
 }

四，界面展示（UI层）

myProject/MyORM/main.go

 package main

 import (
     "myProject/MyORM/Model"
     "myProject/MyORM/Service"
 )

 func main() {
     user := &Model.User{
         Id:        ,
         UID:       "",
         LoginName: "admin",
         PassWord:  "",
     }
     userService := new(Service.UserService)
     userService.Add(user)

     product := &Model.Product{
         Id:    ,
         UID:   "",
         Name:  "苹果",
         Price: 12.5,
     }
     productService := new(Service.ProductService)
     productService.Update(product)
 }