一、大话设计模式 之 简单工厂模式

模式特点：工厂根据条件产生不同功能的类。
程序实例：四则运算计算器，根据用户的输入产生相应的运算类，用这个运算类处理具体的运算。

package mainimport ("fmt")//BaseOperation接口type Operation interface {getResult() float64SetNumA(float64)SetNumB(float64)}type BaseOperation struct {numberA float64numberB float64}func (operation *BaseOperation) SetNumA(numA float64) {operation.numberA = numA}func (operation *BaseOperation) SetNumB(numB float64) {operation.numberB = numB}type OperationAdd struct {BaseOperation}func (this *OperationAdd) getResult() float64 {return this.numberA + this.numberB}type OperationSub struct {BaseOperation}func (this *OperationSub) getResult() float64 {return this.numberA - this.numberB}type OperationMul struct {BaseOperation}func (this *OperationMul) getResult() float64 {return this.numberA * this.numberB}type OperationDiv struct {BaseOperation}func (this *OperationDiv) getResult() float64 {if this.numberB == 0 {panic("被除数不能为0")}return this.numberA / this.numberB}type OperationFactory struct {}func (this *OperationFactory) createOperation(operator string) (operation Operation) {switch operator {case"+":operation = new(OperationAdd)case"-":operation = new(OperationSub)case"/":operation = new(OperationDiv)case"*":operation = new(OperationMul)default:panic("运算符号错误！")}return}func main() {defer func() {if err := recover(); err != nil {fmt.Println(err)}}()var fac OperationFactoryoper := fac.createOperation("/")oper.SetNumA(3.0)oper.SetNumB(0.0)fmt.Println(oper.getResult())}