策略模式

public class StrategyContext {
private IStrategy strategy;

public StrategyContext(IStrategy strategy) {
this.strategy = strategy;
}

public void operate() {
strategy.operation();
}
}

interface IStrategy {
void operation();
}

class StrategyA implements IStrategy {
@Override
public void operation() {
System.out.println("Strategy A");
}
}

class StategyB implements IStrategy {
@Override
public void operation() {
System.out.println("Strategy B");
}
}

class StrategyC implements IStrategy {
@Override
public void operation() {
System.out.println("Strategy C");
}
}