策略模式：定义一系列算法，将它们分别封装起来，让他们之间可以相互替换，但不会影响到使用算法的用户。

 

public interface Strategy {    public void function();}public class ConcreteStrategyOne implements Strategy{    @Override    public void function() {        System.out.println("One.");    }}public class ConcreteStrategyTwo implements Strategy{    @Override    public void function() {        System.out.println("Two.");    }}

 

public class StrategyContext {    private Strategy strategy;    public StrategyContext(Strategy strategy) {        this.strategy = strategy;    }    public void StrategyContextFunction() {        strategy.function();    }}

 

public class StrategyDemo {    public static void main(String[] args) {        StrategyContext contextOne = new StrategyContext(new ConcreteStrategyOne());        contextOne.StrategyContextFunction();        StrategyContext contextTwo = new StrategyContext(new ConcreteStrategyTwo());        contextTwo.StrategyContextFunction();    }}