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装饰器模式

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F嘉阳
2018-09-27 17:16:26 +08:00
parent 4b26f4641e
commit 9ead169b90
9 changed files with 222 additions and 0 deletions
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17
src/main/java/top/fjy8018/designpattern/pattern/structural/decorator/after/ABattercake.java Normal file
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package top.fjy8018.designpattern.pattern.structural.decorator.after;
/**
* @author F嘉阳
* @date 2018-09-27 17:04
*/
public class ABattercake extends AbstractBattercake {
@Override
public String getDesc() {
return "煎饼";
}
@Override
public int cost() {
return 8;
}
}

15
src/main/java/top/fjy8018/designpattern/pattern/structural/decorator/after/AbstractBattercake.java Normal file
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package top.fjy8018.designpattern.pattern.structural.decorator.after;
/**
* 装饰器模式按照业务场景一般有两层抽象，
* 一层是所有类的抽象，一层是所有装饰器的抽象，
* 所有装饰器的抽象可以为实现类提供实现额外功能的能力
*
* @author F嘉阳
* @date 2018-09-27 17:02
*/
public abstract class AbstractBattercake {
public abstract String getDesc();
public abstract int cost();
}

34
src/main/java/top/fjy8018/designpattern/pattern/structural/decorator/after/AbstractBattercakeDecorator.java Normal file
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package top.fjy8018.designpattern.pattern.structural.decorator.after;
/**
* @author F嘉阳
* @date 2018-09-27 17:05
*/
public abstract class AbstractBattercakeDecorator extends AbstractBattercake {
private AbstractBattercake abstractBattercake;
/**
* 通过构造器注入待装饰对象
*
* @param abstractBattercake
*/
public AbstractBattercakeDecorator(AbstractBattercake abstractBattercake) {
this.abstractBattercake = abstractBattercake;
}
/**
* 实现类可以提供额外能力
*/
protected abstract void doSomething();
@Override
public String getDesc() {
return this.abstractBattercake.getDesc();
}
@Override
public int cost() {
return this.abstractBattercake.cost();
}
}

30
src/main/java/top/fjy8018/designpattern/pattern/structural/decorator/after/EggBattercake.java Normal file
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package top.fjy8018.designpattern.pattern.structural.decorator.after;
import lombok.extern.slf4j.Slf4j;
/**
* @author F嘉阳
* @date 2018-09-27 17:08
*/
@Slf4j
public class EggBattercake extends AbstractBattercakeDecorator {
public EggBattercake(AbstractBattercake abstractBattercake) {
super(abstractBattercake);
}
@Override
protected void doSomething() {
log.info("EggBattercake doSomething...");
}
@Override
public String getDesc() {
return super.getDesc() + " 加一个鸡蛋";
}
@Override
public int cost() {
return super.cost() + 1;
}
}

29
src/main/java/top/fjy8018/designpattern/pattern/structural/decorator/after/SausageBattercake.java Normal file
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package top.fjy8018.designpattern.pattern.structural.decorator.after;
import lombok.extern.slf4j.Slf4j;
/**
* @author F嘉阳
* @date 2018-09-27 17:10
*/
@Slf4j
public class SausageBattercake extends AbstractBattercakeDecorator {
public SausageBattercake(AbstractBattercake abstractBattercake) {
super(abstractBattercake);
}
@Override
protected void doSomething() {
log.info("SausageBattercake doSomething...");
}
@Override
public String getDesc() {
return super.getDesc() + " 加一根香肠";
}
@Override
public int cost() {
return super.cost() + 2;
}
}

21
src/main/java/top/fjy8018/designpattern/pattern/structural/decorator/before/Battercake.java Normal file
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package top.fjy8018.designpattern.pattern.structural.decorator.before;
/**
* 装饰器模式：允许向一个现有的对象添加新的功能，同时又不改变其结构。这种类型的设计模式属于结构型模式，它是作为现有的类的一个包装。
* 这种模式创建了一个装饰类，用来包装原有的类，并在保持类方法签名完整性的前提下，提供了额外的功能。
* 优点：继承的有力补充，比继承灵活，不改变原有对象的情况下给一个对象扩展功能
* 通过使用不同装饰器排列组合实现不同效果
* 符合开闭原则
*
* @author F嘉阳
* @date 2018-09-27 16:56
*/
public class Battercake {
protected String getDesc() {
return "煎饼";
}
protected int cost() {
return 8;
}
}

19
src/main/java/top/fjy8018/designpattern/pattern/structural/decorator/before/BattercakeWithEgg.java Normal file
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package top.fjy8018.designpattern.pattern.structural.decorator.before;
/**
* 不使用装饰器则只能通过类继承扩展功能，可能引起类爆炸
*
* @author F嘉阳
* @date 2018-09-27 16:59
*/
public class BattercakeWithEgg extends Battercake {
@Override
protected String getDesc() {
return super.getDesc() + " 加一个鸡蛋";
}
@Override
protected int cost() {
return super.cost() + 1;
}
}

17
src/main/java/top/fjy8018/designpattern/pattern/structural/decorator/before/BattercakeWithEggSausage.java Normal file
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package top.fjy8018.designpattern.pattern.structural.decorator.before;
/**
* @author F嘉阳
* @date 2018-09-27 17:00
*/
public class BattercakeWithEggSausage extends BattercakeWithEgg {
@Override
protected String getDesc() {
return super.getDesc() + " 加一根香肠";
}
@Override
protected int cost() {
return super.cost() + 2;
}
}

40
src/test/java/top/fjy8018/designpattern/pattern/structural/decorator/before/BattercakeTest.java Normal file
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package top.fjy8018.designpattern.pattern.structural.decorator.before;
import lombok.extern.slf4j.Slf4j;
import org.junit.jupiter.api.Test;
import top.fjy8018.designpattern.pattern.structural.decorator.after.ABattercake;
import top.fjy8018.designpattern.pattern.structural.decorator.after.AbstractBattercake;
import top.fjy8018.designpattern.pattern.structural.decorator.after.EggBattercake;
import top.fjy8018.designpattern.pattern.structural.decorator.after.SausageBattercake;
import static org.junit.jupiter.api.Assertions.*;
@Slf4j
class BattercakeTest {
/**
* 通过继承扩展灵活度低，无法自由组合
*/
@Test
void before() {
Battercake battercake = new Battercake();
log.info(battercake.getDesc() + " 销售价格:" + battercake.cost());
Battercake battercakeWithEgg = new BattercakeWithEgg();
log.info(battercakeWithEgg.getDesc() + " 销售价格:" + battercakeWithEgg.cost());
Battercake battercakeWithEggSausage = new BattercakeWithEggSausage();
log.info(battercakeWithEggSausage.getDesc() + " 销售价格:" + battercakeWithEggSausage.cost());
}
@Test
void after() {
// 自由组合装饰
AbstractBattercake battercake = new EggBattercake(new SausageBattercake(new ABattercake()));
log.info(battercake.getDesc() + " 销售价格:" + battercake.cost());
AbstractBattercake battercake2 = new EggBattercake((new ABattercake()));
log.info(battercake2.getDesc() + " 销售价格:" + battercake2.cost());
}
}