Abstract Factory 抽象工廠模式:

以同一個介面來建立一整組相關或相依的物件, 不需要點名個物件真正所屬的具象類別

提供一個建立一系列相關或相互一類物件的介面, 而無需指名他們具體的類別 像是一個集團下有不同的工廠可以生成不同的產品, 每個工廠稱產出來的同一個型號產品具體細節是不一樣

Example

https://github.com/kimi0230/DesignPatternGolang/tree/master/AbstractFactory

package abstractfactory

import "fmt"

type User struct {
    id   int
    name string
}

func (u *User) Id() int {
    if u == nil {
        return -1
    }
    return u.id
}

func (u *User) SetId(id int) {
    if u == nil {
        return
    }
    u.id = id
}

func (u *User) Name() string {
    if u == nil {
        return ""
    }
    return u.name
}

func (u *User) SetName(name string) {
    if u == nil {
        return
    }
    u.name = name
}

type Department struct {
    id   int
    name string
}

func (d *Department) Id() int {
    if d == nil {
        return -1
    }
    return d.id
}
func (d *Department) SetId(id int) {
    if d == nil {
        return
    }
    d.id = id
}
func (d *Department) Name() string {
    if d == nil {
        return ""
    }
    return d.name
}
func (d *Department) SetName(name string) {
    if d == nil {
        return
    }
    d.name = name
}

type IUser interface {
    Insert(*User)
    GetUser(int) *User
}

type SqlServerUser struct {
}

func (s *SqlServerUser) Insert(u *User) {
    if s == nil {
        return
    }
    fmt.Println("在 Sql Server 中給 User insert 一筆紀錄", u)
}

func (s *SqlServerUser) GetUser(id int) (u *User) {
    if s == nil {
        return nil
    }
    u = &User{id, "kk"}
    fmt.Println("在 Sql Server 中根據 id 得到 User 紀錄", *u)
    return u
}

type AccessUser struct {
}

func (a *AccessUser) Insert(u *User) {
    if a == nil {
        return
    }
    fmt.Println("在 Access 中給 Department insert 一筆紀錄", *u)
}

func (a *AccessUser) GetUser(id int) (u *User) {
    if a == nil {
        return nil
    }
    u = &User{id, "kk"}
    fmt.Println("在 Access 中根據 id 得到 User 紀錄", *u)
    return u
}

// 用於用戶端存取 解除與具體資料庫存取的耦合
type IDepartment interface {
    Insert(*Department)
    GetDepartment(int) *Department
}

// 用於存取 SQL server的 Department
type SqlServerDepartment struct {
}

func (s *SqlServerDepartment) Insert(d *Department) {
    if s == nil {
        return
    }
    fmt.Println("在 Sql Server 中給 Department insert 一筆紀錄", *d)
}

func (s *SqlServerDepartment) GetDepartment(id int) (d *Department) {
    if s == nil {
        return nil
    }
    d = &Department{id, "dd"}
    fmt.Println("在 Sql Server 中根據 id 得到 Department 紀錄", *d)
    return d
}

// 用於存取 Access的 Department
type AccessDepartment struct {
}

func (a *AccessDepartment) Insert(d *Department) {
    if a == nil {
        return
    }
    fmt.Println("在 Access 中給 Department insert 一筆紀錄", *d)
}

func (a *AccessDepartment) GetDepartment(id int) (d *Department) {
    if a == nil {
        return nil
    }
    d = &Department{id, "dd"}
    fmt.Println("在 Access 中根據 id 得到 Department 紀錄", *d)
    return d
}

// 定義一個建立存取 User, Department 物件的抽象工廠介面
type IFactory interface {
    CreateUser() IUser
    CreateDepartment() IDepartment
}

// 實現 IFactory 介面
type SqlServerFactory struct{}

func (s *SqlServerFactory) CreateUser() IUser {
    if s == nil {
        return nil
    }
    u := &SqlServerUser{}
    return u

}
func (s *SqlServerFactory) CreateDepartment() IDepartment {
    if s == nil {
        return nil
    }
    d := &SqlServerDepartment{}
    return d
}

// 實現 IFactory 介面
type AccessFactory struct{}

func (a *AccessFactory) CreateUser() IUser {
    if a == nil {
        return nil
    }
    u := &AccessUser{}
    return u

}
func (a *AccessFactory) CreateDepartment() IDepartment {
    if a == nil {
        return nil
    }
    d := &AccessDepartment{}
    return d
}

// 用簡單工廠來改進抽象工廠
type DataAccess struct {
    db string
}

func (d *DataAccess) CreateUser() IUser {
    if d == nil {
        return nil
    }

    var u IUser

    if d.db == "sqlserver" {
        u = new(SqlServerUser)
    } else if d.db == "access" {
        u = new(AccessUser)
    }
    return u
}

func (d *DataAccess) CreateDepartment() IDepartment {
    if d == nil {
        return nil
    }

    var u IDepartment

    if d.db == "sqlserver" {
        u = new(SqlServerDepartment)
    } else if d.db == "access" {
        u = new(AccessDepartment)
    }
    return u
}