Golang策略模式应用场景 使用接口实现算法替换方案

package main

import "fmt"

// OperationStrategy 定义了策略接口，所有具体的运算策略都必须实现这个接口
type OperationStrategy interface {
    Execute(a, b int) int
}

// AddStrategy 加法策略
type AddStrategy struct{}

func (s *AddStrategy) Execute(a, b int) int {
    return a + b
}

// SubtractStrategy 减法策略
type SubtractStrategy struct{}

func (s *SubtractStrategy) Execute(a, b int) int {
    return a - b
}

// MultiplyStrategy 乘法策略
type MultiplyStrategy struct{}

func (s *MultiplyStrategy) Execute(a, b int) int {
    return a * b
}

// CalculatorContext 是上下文，它持有 OperationStrategy 接口的实例
type CalculatorContext struct {
    strategy OperationStrategy
}

// SetStrategy 允许在运行时改变策略
func (c *CalculatorContext) SetStrategy(strategy OperationStrategy) {
    c.strategy = strategy
}

// ExecuteStrategy 执行当前设置的策略
func (c *CalculatorContext) ExecuteStrategy(a, b int) int {
    if c.strategy == nil {
        fmt.Println("Error: No strategy set.")
        return 0 // 或者返回错误
    }
    return c.strategy.Execute(a, b)
}

func main() {
    context := &CalculatorContext{}

    // 使用加法策略
    context.SetStrategy(&AddStrategy{})
    resultAdd := context.ExecuteStrategy(10, 5)
    fmt.Printf("10 + 5 = %d\n", resultAdd)

    // 切换到减法策略
    context.SetStrategy(&SubtractStrategy{})
    resultSubtract := context.ExecuteStrategy(10, 5)
    fmt.Printf("10 - 5 = %d\n", resultSubtract)

    // 切换到乘法策略
    context.SetStrategy(&MultiplyStrategy{})
    resultMultiply := context.ExecuteStrategy(10, 5)
    fmt.Printf("10 * 5 = %d\n", resultMultiply)

    // 甚至可以动态地添加新的策略，比如除法，而无需修改 CalculatorContext
    // type DivideStrategy struct{}
    // func (s *DivideStrategy) Execute(a, b int) int {
    //     if b == 0 { return 0 } // 实际应用需要更完善的错误处理
    //     return a / b
    // }
    // context.SetStrategy(&DivideStrategy{})
    // resultDivide := context.ExecuteStrategy(10, 5)
    // fmt.Printf("10 / 5 = %d\n", resultDivide)
}

OperationStrategy

AddStrategy

SubtractStrategy

MultiplyStrategy

CalculatorContext

SetStrategy

ExecuteStrategy

PaymentStrategy

WeChatPayStrategy

AlipayStrategy

CreditCardPayStrategy

ExportStrategy

CSVExportStrategy

ExcelExportStrategy

PDFExportStrategy

LogStrategy

if-else if

switch