设计模式学习----策略模式

【策略模式解释】

类型：行为模式

定义一组算法，将每个算法都封装起来，并且使它们之间可以互换。策略模式使这些算法在客户端调用它们的时候能够互不影响地变化。

UML图如下:



新建一个轮胎接口：

package strategy_interface;
public interface tyre_interface {
// tyre 轮胎
public void print_tyre_line();// 显示出轮胎的痕迹
}

新建2个轮胎接口的实现类：

package strategy_implement;
import strategy_interface.tyre_interface;
//长痕迹轮胎类
public class tyre_long_implement implements tyre_interface {
public void print_tyre_line() {
System.out.println("在路面上显示一个长轮胎痕迹");
}
}

package strategy_implement;
import strategy_interface.tyre_interface;
//短痕迹轮胎类
public class tyre_short_implement implements tyre_interface {
public void print_tyre_line() {
System.out.println("在路面上显示一个短轮胎痕迹");
}
}

组装一个Car车类：

package car_package;
import strategy_interface.tyre_interface;
public class Car {
private String make_address;// 制造地
private int death_year;// 报废年限
private int speed;// 速度
private tyre_interface tyre_interface_ref;// 轮胎的样式
public String getMake_address() {
return make_address;
}
public void setMake_address(String make_address) {
this.make_address = make_address;
}
public int getDeath_year() {
return death_year;
}
public void setDeath_year(int death_year) {
this.death_year = death_year;
}
public int getSpeed() {
return speed;
}
public void setSpeed(int speed) {
this.speed = speed;
}
public tyre_interface getTyre_interface_ref() {
return tyre_interface_ref;
}
public void setTyre_interface_ref(tyre_interface tyre_interface_ref) {
this.tyre_interface_ref = tyre_interface_ref;
}
public void start() {
System.out.println("车的基本信息为：");
System.out.println("制造地make_address：" + this.getMake_address());
System.out.println("报废年限death_year：" + this.getDeath_year());
System.out.println("速度speed：" + this.getSpeed());

System.out.println("Car 起动了！");

System.out.println("Car高速行驶，遇到一个大转弯，路面显示：");
this.getTyre_interface_ref().print_tyre_line();
}
}

让车跑起来，并且具有更换轮胎样式的功能：
package main_run;
import strategy_implement.tyre_long_implement;
import strategy_implement.tyre_short_implement;
import car_package.Car;
public class run_main {
public static void main(String[] args) {
tyre_long_implement tyre_long_implement = new tyre_long_implement();
tyre_short_implement tyre_short_implement = new tyre_short_implement();
Car car = new Car();
car.setDeath_year(8);
car.setMake_address("北京朝阳区");
car.setSpeed(200);
car.setTyre_interface_ref(tyre_long_implement);
car.start();
}
}

另一个例子

public abstract class Duck{
FlyBehavior flyBehavior;
QuackBehavior quackBehavior;
public Duck()
{
}
public abstract void display();
public void performFly()
{
flyBehavior.fly();
}
public void performQuack()
{
quackBehavior.quack();
}
public void swim()
{
System.out.println("All ducks float,even decoys!");
}

}

public interface FlyBehavior
{
public void fly();
}

public class FlyWithWings implements FlyBehavior
{
public void fly()
{
System.out.println("i'm flying");
}
}

public class FlyNoWay implements FlyBehavior
{
public void fly()
{
System.out.println("i can't fly");
}
}

public interfaceQuackBehavior
{
public void quack();
}

public class Quack implements QuackBehavior
{
public void quack()
{
System.out.println("quack");
}
}

public class MuteQuack implements QuackBehavior
{
public void quack()
{
System.out.println("silence");
}
}

public class Squeak implements QuackBehavior
{
public void quack()
{
System.out.println("Squeak");
}
}

public class MallardDuck extends Duck{
public MallardDuck()
{
flyBehavior =new Quack();
quackBehavior =new FlyWithWings();
}

}
public class MiniDuckSimulator
{
public static void main(String[] args)
{
Duck mallard = new MallardDuck();
mallard.performFly();
mallard.performQuack();
}
}