[设计模式 Go实现] 创建型～工厂方法模式-编程知识

[设计模式 Go实现] 创建型～工厂方法模式

工厂方法模式使用子类的方式延迟生成对象到子类中实现。

Go中不存在继承所以使用匿名组合来实现

代码实现

package factorymethod//Operator 是被封装的实际类接口
type Operator interface {SetA(int)SetB(int)Result() int
}//OperatorFactory 是工厂接口
type OperatorFactory interface {Create() Operator
}//OperatorBase 是Operator 接口实现的基类，封装公用方法
type OperatorBase struct {a, b int
}//SetA 设置 A
func (o *OperatorBase) SetA(a int) {o.a = a
}//SetB 设置 B
func (o *OperatorBase) SetB(b int) {o.b = b
}//PlusOperatorFactory 是 PlusOperator 的工厂类
type PlusOperatorFactory struct{}func (PlusOperatorFactory) Create() Operator {return &PlusOperator{OperatorBase: &OperatorBase{},}
}//PlusOperator Operator 的实际加法实现
type PlusOperator struct {*OperatorBase
}//Result 获取结果
func (o PlusOperator) Result() int {return o.a + o.b
}//MinusOperatorFactory 是 MinusOperator 的工厂类
type MinusOperatorFactory struct{}func (MinusOperatorFactory) Create() Operator {return &MinusOperator{OperatorBase: &OperatorBase{},}
}//MinusOperator Operator 的实际减法实现
type MinusOperator struct {*OperatorBase
}//Result 获取结果
func (o MinusOperator) Result() int {return o.a - o.b
}

单元测试

package factorymethodimport "testing"func compute(factory OperatorFactory, a, b int) int {op := factory.Create()op.SetA(a)op.SetB(b)return op.Result()
}func TestOperator(t *testing.T) {var (factory OperatorFactory)factory = PlusOperatorFactory{}if compute(factory, 1, 2) != 3 {t.Fatal("error with factory method pattern")}factory = MinusOperatorFactory{}if compute(factory, 4, 2) != 2 {t.Fatal("error with factory method pattern")}
}