命令模式
- 1.什么是命令模式
- 2.命令模式的角色
- 3.模式图
- 4.例子
- 4.1例子背景
- 4.2 结构图
- 4.3 命令接口
- 4.4 命令抽象方法
- 4.5 实现的命令
- 4.6 命令的集合
- 4.7 抽象的持有者
- 4.8 实现的持有者
- 4.9 命令的发动者
- 4.10 命令的请求者
- 4.11 结果
- 5.总结
- 5.1 命令的享元工厂
- 5.2 执行者的享元工厂
- 5.2.1抽象的命令的集合：
- 5.2.2具体的命令的集合
- 5.2.3 抽象的命令的发动者
- 5.2.4 具体的命令的发动者
- 5.2.5 调用者
- 5.2.6 结果
- 5.2.7 说明
23种设计模式
1.什么是命令模式
命令就是需要自己命令的对象进行的操作。
首先，分为两个方面：
对于命令方，命令是最小单位。
对于被命令方，命令是最大单位。
其次：
命令有发出角色，有执行角色。
同时：
命令有发出时间，有执行时间。
等等。
所以，命令模式主要解决就是把一系列复杂的操作，（相对不变）封装起来，等到需要再次调用时，不需要创建，只需要调用即可。
命令模式大大的降低了使用者的条件，但是却可能变相的增加提供者的条件。
举个例子：使用接口封装的服务，可能对于提供者来说比较容易实现，但是对于调用者来说，调用可能比较困难。
而使用命令模式，可以大大的较低调用者的使用难度，相应的，提供者的提供难度将会增加。
2.命令模式的角色
抽象的命令：定义命令需要实现什么操作
实现的命令 ：抽象的命令进行实现
命令的执行者：命令将由这个角色进行执行
命令的请求者：发起命令的角色
命令的发动者：决定何时执行命令
一般来说：命令的请求者持有命令，实现的命令持有命令的执行者，命令的执行者决定时间。
3.模式图
实现
持有
持有
决定
实现的命令
抽象的命令
命令的执行者
命令的请求者
命令的发动者
从上图可以看出，命令模式几乎完全解耦了调用者和提供者的关系。
调用者几乎不需要了解操作是如何实现的。
调用者只需要发起命令的请求。
4.例子
实例源码下载传送门(资源暂未审核，通过后及时增加)
4.1例子背景
现在生活条件上升，很多人都有了自己的小汽车，所以，很多人都会开车。
下面的例子就是关于如何开车。
首先，开车的步骤大家都知道。
举一个例子：起步：
起步需要：
- 系安全带
- 左转向灯
- 左转向
- 刹车
- 点火
- 离合
- 挂挡
- 给油
为了简单，在本次例子中，离合就认为是踩下离合并且在合适的时间释放离合，刹车也是，给油认为是根据需要踩给油踏板。
4.2 结构图
4.3 命令接口
package order.intf;
public interface IntfCommand {
void execute();
}
4.4 命令抽象方法
package order.abs;
import order.intf.IntfCommand;
import receive.abs.AbsCar;
public abstract class AbsCommand implements IntfCommand{
protected AbsCar absCar;
public AbsCommand(){
init();
}
protected abstract void init();
@Override
public void execute() {
System.out.println(this.getClass() + "\texecute\t"
+ this);
absCar.receive();
}
}
4.5 实现的命令
package order.command;
import order.abs.AbsCommand;
import receive.component.BrakeRec;
/**
*
* 刹车
*/
public class BrakeComm extends AbsCommand {
@Override
protected void init() {
absCar = new BrakeRec();
System.out.println(this.getClass() + ":" + this
+ "\tinit\t" + absCar.getClass() + ":"
+ absCar);
}
}
package order.command;
import order.abs.AbsCommand;
import receive.component.ClutchRec;
/**
*
* 离合
*/
public class ClutchComm extends AbsCommand {
@Override
protected void init() {
absCar = new ClutchRec();
System.out.println(this.getClass() + ":" + this
+ "\tinit\t" + absCar.getClass() + ":"
+ absCar);
}
}
package order.command;
import order.abs.AbsCommand;
import receive.component.HangOutRec;
/**
*
* 挂挡
*/
public class HangOutComm extends AbsCommand {
@Override
protected void init() {
absCar = new HangOutRec();
System.out.println(this.getClass() + ":" + this
+ "\tinit\t" + absCar.getClass() + ":"
+ absCar);
}
}
package order.command;
import order.abs.AbsCommand;
import receive.component.IgnitionRec;
/**
* 点火
*
*/
public class IgnitionComm extends AbsCommand {
@Override
protected void init() {
absCar = new IgnitionRec();
System.out.println(this.getClass() + ":" + this
+ "\tinit\t" + absCar.getClass() + ":"
+ absCar);
}
}
package order.command;
import order.abs.AbsCommand;
import receive.component.OilRec;
/**
* 给油
*
*/
public class OilComm extends AbsCommand {
@Override
protected void init() {
absCar = new OilRec();
System.out.println(this.getClass() + ":" + this
+ "\tinit\t" + absCar.getClass() + ":"
+ absCar);
}
}
package order.command;
import order.abs.AbsCommand;
import receive.component.PutOutRec;
/**
*
* 熄火
*/
public class PutOutComm extends AbsCommand {
@Override
protected void init() {
absCar = new PutOutRec();
System.out.println(this.getClass() + ":" + this
+ "\tinit\t" + absCar.getClass() + ":"
+ absCar);
}
}
package order.command;
import order.abs.AbsCommand;
import receive.component.SteeringWheelLeftRec;
/**
*
* 左打方向盘
*/
public class SteeringWheelLeftComm extends AbsCommand {
@Override
protected void init() {
absCar = new SteeringWheelLeftRec();
System.out.println(this.getClass() + ":" + this
+ "\tinit\t" + absCar.getClass() + ":"
+ absCar);
}
}
package order.command;
import order.abs.AbsCommand;
import receive.component.SteeringWheelRightRec;
/**
*
* 右打方向盘
*/
public class SteeringWheelRightComm extends AbsCommand {
@Override
protected void init() {
absCar = new SteeringWheelRightRec();
System.out.println(this.getClass() + ":" + this
+ "\tinit\t" + absCar.getClass() + ":"
+ absCar);
}
}
package order.command;
import order.abs.AbsCommand;
import receive.component.TurnSignalLeftRec;
/**
*
* 左转向灯
*/
public class TurnSignalLeftComm extends AbsCommand {
@Override
protected void init() {
absCar = new TurnSignalLeftRec();
System.out.println(this.getClass() + ":" + this
+ "\tinit\t" + absCar.getClass() + ":"
+ absCar);
}
}
package order.command;
import order.abs.AbsCommand;
import receive.component.TurnSignalRightRec;
/**
*
* 右转向灯
*/
public class TurnSignalRightComm extends AbsCommand {
@Override
protected void init() {
absCar = new TurnSignalRightRec();
System.out.println(this.getClass() + ":" + this
+ "\tinit\t" + absCar.getClass() + ":"
+ absCar);
}
}
package order.command;
import order.abs.AbsCommand;
import receive.component.WearingSeatbeltRec;
/**
*
* 系安全带
*/
public class WearingSeatbeltComm extends AbsCommand {
@Override
protected void init() {
absCar = new WearingSeatbeltRec();
System.out.println(this.getClass() + ":" + this
+ "\tinit\t" + absCar.getClass() + ":"
+ absCar);
}
}
4.6 命令的集合
package order.step;
import java.util.LinkedList;
import java.util.Queue;
import order.command.BrakeComm;
import order.command.ClutchComm;
import order.command.HangOutComm;
import order.command.IgnitionComm;
import order.command.OilComm;
import order.command.SteeringWheelLeftComm;
import order.command.TurnSignalLeftComm;
import order.command.WearingSeatbeltComm;
import order.intf.IntfCommand;
/**
* 车起步：
*
* 系安全带
* 左转向灯
* 左转向
* 刹车
* 点火
* 离合
* 挂挡
* 给油
*
*/
public class CarStart implements IntfCommand{
private Queue<IntfCommand> step = new LinkedList<IntfCommand>();
public CarStart() {
init();
}
private void init(){
step.add(new WearingSeatbeltComm());
step.add(new TurnSignalLeftComm());
step.add(new SteeringWheelLeftComm());
step.add(new BrakeComm());
step.add(new IgnitionComm());
step.add(new ClutchComm());
step.add(new HangOutComm());
step.add(new OilComm());
System.out.println(this.getClass().getName() + "\tinit\t"
+ step.getClass().getName());
}
@Override
public void execute() {
System.out.println(this.getClass() + "\texecute\t"
+ this);
IntfCommand command = step.poll();
while(command != null){
command.execute();
command = step.poll();
}
}
}
4.7 抽象的持有者
package receive.abs;
public abstract class AbsCar {
public void receive(){
System.out.println(this.getClass() + "\treceive\t"
+ this);
doReceive();
}
protected abstract void doReceive();
}
4.8 实现的持有者
package receive.component;
import receive.abs.AbsCar;
/**
*
* 刹车
*/
public class BrakeRec extends AbsCar{
@Override
protected void doReceive() {
System.out.println(this.getClass() + "\tdoReceive\t"
+ this);
System.out.println("刹车");
}
}
package receive.component;
import receive.abs.AbsCar;
/**
*
* 离合
*/
public class ClutchRec extends AbsCar{
@Override
protected void doReceive() {
System.out.println(this.getClass() + "\tdoReceive\t"
+ this);
System.out.println("离合");
}
}
package receive.component;
import receive.abs.AbsCar;
/**
*
* 挂挡
*/
public class HangOutRec extends AbsCar{
@Override
protected void doReceive() {
System.out.println(this.getClass() + "\tdoReceive\t"
+ this);
System.out.println("挂挡");
}
}
package receive.component;
import receive.abs.AbsCar;
/**
* 点火
*
*/
public class IgnitionRec extends AbsCar{
@Override
protected void doReceive() {
System.out.println(this.getClass() + "\tdoReceive\t"
+ this);
System.out.println("点火");
}
}
package receive.component;
import receive.abs.AbsCar;
/**
* 给油
*
*/
public class OilRec extends AbsCar{
@Override
protected void doReceive() {
System.out.println(this.getClass() + "\tdoReceive\t"
+ this);
System.out.println("给油");
}
}
package receive.component;
import receive.abs.AbsCar;
/**
*
* 熄火
*/
public class PutOutRec extends AbsCar{
@Override
protected void doReceive() {
System.out.println(this.getClass() + "\tdoReceive\t"
+ this);
System.out.println("熄火");
}
}
package receive.component;
import receive.abs.AbsCar;
/**
*
* 左打方向盘
*/
public class SteeringWheelLeftRec extends AbsCar {
@Override
protected void doReceive() {
System.out.println(this.getClass() + "\tdoReceive\t"
+ this);
System.out.println("左打方向盘");
}
}
package receive.component;
import receive.abs.AbsCar;
/**
*
* 右打方向盘
*/
public class SteeringWheelRightRec extends AbsCar{
@Override
protected void doReceive() {
System.out.println(this.getClass() + "\tdoReceive\t"
+ this);
System.out.println("右打方向盘");
}
}
package receive.component;
import receive.abs.AbsCar;
/**
*
* 左转向灯
*/
public class TurnSignalLeftRec extends AbsCar{
@Override
protected void doReceive() {
System.out.println(this.getClass() + "\tdoReceive\t"
+ this);
System.out.println("左转向灯");
}
}
package receive.component;
import receive.abs.AbsCar;
/**
*
* 右转向灯
*/
public class TurnSignalRightRec extends AbsCar{
@Override
protected void doReceive() {
System.out.println(this.getClass() + "\tdoReceive\t"
+ this);
System.out.println("右转向灯");
}
}
package receive.component;
import receive.abs.AbsCar;
/**
*
* 系安全带
*/
public class WearingSeatbeltRec extends AbsCar{
@Override
protected void doReceive() {
System.out.println(this.getClass() + "\tdoReceive\t"
+ this);
System.out.println("系安全带");
}
}
4.9 命令的发动者
package receive.car;
import receive.abs.AbsCar;
/**
* 车起步：
*
* 系安全带 左转向灯 左转向 刹车 点火 离合 挂挡 给油
*
*/
public class CarStart extends AbsCar {
private order.step.CarStart carStart;
public CarStart() {
init();
}
private void init() {
carStart = new order.step.CarStart();
System.out.println(this.getClass() + ":" + this
+ "\tinit\t" + carStart.getClass() + ":"
+ carStart);
}
@Override
protected void doReceive() {
System.out.println(this.getClass().getName() + "\tdoReceive\t"
+ this.getClass());
carStart.execute();
}
}
4.10 命令的请求者
package client;
import receive.car.CarStart;
public class Main {
public static void main(String[] args) {
System.out.println("生成命令");
CarStart carStart = new CarStart();
System.out.println("执行命令");
carStart.receive();
}
}
4.11 结果
生成命令
class order.command.WearingSeatbeltComm:order.command.WearingSeatbeltComm@1befab0 init class receive.component.WearingSeatbeltRec:receive.component.WearingSeatbeltRec@13c5982
class order.command.TurnSignalLeftComm:order.command.TurnSignalLeftComm@c21495 init class receive.component.TurnSignalLeftRec:receive.component.TurnSignalLeftRec@1d5550d
class order.command.SteeringWheelLeftComm:order.command.SteeringWheelLeftComm@1034bb5 init class receive.component.SteeringWheelLeftRec:receive.component.SteeringWheelLeftRec@15f5897
class order.command.BrakeComm:order.command.BrakeComm@186d4c1 init class receive.component.BrakeRec:receive.component.BrakeRec@f9f9d8
class order.command.IgnitionComm:order.command.IgnitionComm@87816d init class receive.component.IgnitionRec:receive.component.IgnitionRec@422ede
class order.command.ClutchComm:order.command.ClutchComm@93dcd init class receive.component.ClutchRec:receive.component.ClutchRec@b89838
class order.command.HangOutComm:order.command.HangOutComm@a83b8a init class receive.component.HangOutRec:receive.component.HangOutRec@dd20f6
class order.command.OilComm:order.command.OilComm@22c95b init class receive.component.OilRec:receive.component.OilRec@1d1acd3
order.step.CarStart init java.util.LinkedList
class receive.car.CarStart:receive.car.CarStart@a981ca init class order.step.CarStart:order.step.CarStart@8814e9
执行命令
class receive.car.CarStart receive receive.car.CarStart@a981ca
receive.car.CarStart doReceive class receive.car.CarStart
class order.step.CarStart execute order.step.CarStart@8814e9
class order.command.WearingSeatbeltComm execute order.command.WearingSeatbeltComm@1befab0
class receive.component.WearingSeatbeltRec receive receive.component.WearingSeatbeltRec@13c5982
class receive.component.WearingSeatbeltRec doReceive receive.component.WearingSeatbeltRec@13c5982
系安全带
class order.command.TurnSignalLeftComm execute order.command.TurnSignalLeftComm@c21495
class receive.component.TurnSignalLeftRec receive receive.component.TurnSignalLeftRec@1d5550d
class receive.component.TurnSignalLeftRec doReceive receive.component.TurnSignalLeftRec@1d5550d
左转向灯
class order.command.SteeringWheelLeftComm execute order.command.SteeringWheelLeftComm@1034bb5
class receive.component.SteeringWheelLeftRec receive receive.component.SteeringWheelLeftRec@15f5897
class receive.component.SteeringWheelLeftRec doReceive receive.component.SteeringWheelLeftRec@15f5897
左打方向盘
class order.command.BrakeComm execute order.command.BrakeComm@186d4c1
class receive.component.BrakeRec receive receive.component.BrakeRec@f9f9d8
class receive.component.BrakeRec doReceive receive.component.BrakeRec@f9f9d8
刹车
class order.command.IgnitionComm execute order.command.IgnitionComm@87816d
class receive.component.IgnitionRec receive receive.component.IgnitionRec@422ede
class receive.component.IgnitionRec doReceive receive.component.IgnitionRec@422ede
点火
class order.command.ClutchComm execute order.command.ClutchComm@93dcd
class receive.component.ClutchRec receive receive.component.ClutchRec@b89838
class receive.component.ClutchRec doReceive receive.component.ClutchRec@b89838
离合
class order.command.HangOutComm execute order.command.HangOutComm@a83b8a
class receive.component.HangOutRec receive receive.component.HangOutRec@dd20f6
class receive.component.HangOutRec doReceive receive.component.HangOutRec@dd20f6
挂挡
class order.command.OilComm execute order.command.OilComm@22c95b
class receive.component.OilRec receive receive.component.OilRec@1d1acd3
class receive.component.OilRec doReceive receive.component.OilRec@1d1acd3
给油
5.总结
可以看到上面的例子中new了非常多的对象。而且new出来的这些对象基本上都相同。
所以，能不能使用享元模式提高性能。
5.1 命令的享元工厂
package order.flyweight;
import java.util.HashMap;
import java.util.Map;
import order.abs.AbsCommand;
public class FlyWeightComm {
private static Map<String, AbsCommand> map = new HashMap<String, AbsCommand>();
private static final FlyWeightComm instance = new FlyWeightComm();
private FlyWeightComm(){
}
public static FlyWeightComm getInstance(){
return instance;
}
public static AbsCommand getAbsCommand(String comm){
if(map.containsKey(comm)){
return map.get(comm);
} else {
AbsCommand command = null;
try {
command = (AbsCommand)Class.forName("order.command."+comm).newInstance();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
map.put(comm, command);
return command;
}
}
}
5.2 执行者的享元工厂
package receive.flyweight;
import java.util.HashMap;
import java.util.Map;
import receive.abs.AbsCar;
public class FlyWeightRec {
private static Map<String, AbsCar> map = new HashMap<String, AbsCar>();
private static final FlyWeightRec instance = new FlyWeightRec();
private FlyWeightRec(){
}
public static FlyWeightRec getInstance(){
return instance;
}
public static AbsCar getAbsCar(String recName){
if(map.containsKey(recName)){
return map.get(recName);
} else {
AbsCar absCar = null;
try {
absCar = (AbsCar)Class.forName("receive.component."+recName).newInstance();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
map.put(recName, absCar);
return absCar;
}
}
}
结果完全相同。
但是我们在增加一种操作：
加速：
给油、离合、挂挡、给油。
加的时候发现命令的集合这个角色的类的相似度非常的高，所以我们对命令的角色的类进行重构：抽取抽象类：
5.2.1抽象的命令的集合：
package order.step.abs;
import java.util.LinkedList;
import java.util.Queue;
import order.intf.IntfCommand;
public abstract class CarCommAbs implements IntfCommand{
protected Queue<IntfCommand> step = new LinkedList<IntfCommand>();
public CarCommAbs() {
init();
}
protected abstract void init();
@Override
public void execute() {
System.out.println(this.getClass() + "\texecute\t"
+ this);
IntfCommand command = step.poll();
while(command != null){
command.execute();
command = step.poll();
}
}
}
5.2.2具体的命令的集合
package order.step.impl;
import order.flyweight.FlyWeightComm;
import order.step.abs.CarCommAbs;
/**
* 车起步：
*
* 系安全带
* 左转向灯
* 左转向
* 刹车
* 点火
* 离合
* 挂挡
* 给油
*
*/
public class CarStartComm extends CarCommAbs{
@Override
protected void init(){
step.add(FlyWeightComm.getAbsCommand("WearingSeatbeltComm"));
step.add(FlyWeightComm.getAbsCommand("TurnSignalLeftComm"));
step.add(FlyWeightComm.getAbsCommand("SteeringWheelLeftComm"));
step.add(FlyWeightComm.getAbsCommand("BrakeComm"));
step.add(FlyWeightComm.getAbsCommand("IgnitionComm"));
step.add(FlyWeightComm.getAbsCommand("ClutchComm"));
step.add(FlyWeightComm.getAbsCommand("HangOutComm"));
step.add(FlyWeightComm.getAbsCommand("OilComm"));
System.out.println(this.getClass().getName() + "\tinit\t"
+ step.getClass().getName());
}
}
package order.step.impl;
import order.flyweight.FlyWeightComm;
import order.step.abs.CarCommAbs;
public class CarAddComm extends CarCommAbs{
@Override
protected void init() {
step.add(FlyWeightComm.getAbsCommand("OilComm"));
step.add(FlyWeightComm.getAbsCommand("ClutchComm"));
step.add(FlyWeightComm.getAbsCommand("HangOutComm"));
step.add(FlyWeightComm.getAbsCommand("OilComm"));
}
}
5.2.3 抽象的命令的发动者
package receive.car.abs;
import order.step.abs.CarCommAbs;
import receive.abs.AbsCar;
public abstract class CarRecAbs extends AbsCar{
protected CarCommAbs carStart;
public CarRecAbs() {
init();
}
protected abstract void init();
@Override
protected void doReceive() {
System.out.println(this.getClass().getName() + "\tdoReceive\t"
+ this.getClass());
carStart.execute();
}
}
5.2.4 具体的命令的发动者
package receive.car.impl;
import order.step.impl.CarAddComm;
import receive.car.abs.CarRecAbs;
public class CarAddRec extends CarRecAbs{
@Override
protected void init() {
carStart = new CarAddComm();
System.out.println(this.getClass() + ":" + this
+ "\tinit\t" + carStart.getClass() + ":"
+ carStart);
}
}
package receive.car.impl;
import order.step.impl.CarStartComm;
import receive.car.abs.CarRecAbs;
/**
* 车起步：
*
* 系安全带 左转向灯 左转向 刹车 点火 离合 挂挡 给油
*
*/
public class CarStartRec extends CarRecAbs {
@Override
protected void init() {
carStart = new CarStartComm();
System.out.println(this.getClass() + ":" + this
+ "\tinit\t" + carStart.getClass() + ":"
+ carStart);
}
}
5.2.5 调用者
package client;
import receive.car.impl.CarAddRec;
import receive.car.impl.CarStartRec;
public class Main {
public static void main(String[] args) {
System.out.println("生成命令----起步");
CarStartRec carStart = new CarStartRec();
System.out.println("生成命令----加速");
CarAddRec carAddRec = new CarAddRec();
System.out.println("执行命令----加速");
carStart.receive();
System.out.println("执行命令----加速");
carAddRec.receive();
}
}
5.2.6 结果
生成命令----起步
class order.command.WearingSeatbeltComm:order.command.WearingSeatbeltComm@c2ea3f init class receive.component.WearingSeatbeltRec:receive.component.WearingSeatbeltRec@a0dcd9
class order.command.TurnSignalLeftComm:order.command.TurnSignalLeftComm@b162d5 init class receive.component.TurnSignalLeftRec:receive.component.TurnSignalLeftRec@1cfb549
class order.command.SteeringWheelLeftComm:order.command.SteeringWheelLeftComm@1820dda init class receive.component.SteeringWheelLeftRec:receive.component.SteeringWheelLeftRec@15b7986
class order.command.BrakeComm:order.command.BrakeComm@112f614 init class receive.component.BrakeRec:receive.component.BrakeRec@1d9dc39
class order.command.IgnitionComm:order.command.IgnitionComm@111a3ac init class receive.component.IgnitionRec:receive.component.IgnitionRec@110b053
class order.command.ClutchComm:order.command.ClutchComm@19efb05 init class receive.component.ClutchRec:receive.component.ClutchRec@723d7c
class order.command.HangOutComm:order.command.HangOutComm@a981ca init class receive.component.HangOutRec:receive.component.HangOutRec@8814e9
class order.command.OilComm:order.command.OilComm@743399 init class receive.component.OilRec:receive.component.OilRec@e7b241
order.step.impl.CarStartComm init java.util.LinkedList
class receive.car.impl.CarStartRec:receive.car.impl.CarStartRec@167d940 init class order.step.impl.CarStartComm:order.step.impl.CarStartComm@e83912
生成命令----加速
class receive.car.impl.CarAddRec:receive.car.impl.CarAddRec@1d8957f init class order.step.impl.CarAddComm:order.step.impl.CarAddComm@3ee284
执行命令----加速
class receive.car.impl.CarStartRec receive receive.car.impl.CarStartRec@167d940
receive.car.impl.CarStartRec doReceive class receive.car.impl.CarStartRec
class order.step.impl.CarStartComm execute order.step.impl.CarStartComm@e83912
class order.command.WearingSeatbeltComm execute order.command.WearingSeatbeltComm@c2ea3f
class receive.component.WearingSeatbeltRec receive receive.component.WearingSeatbeltRec@a0dcd9
class receive.component.WearingSeatbeltRec doReceive receive.component.WearingSeatbeltRec@a0dcd9
系安全带
class order.command.TurnSignalLeftComm execute order.command.TurnSignalLeftComm@b162d5
class receive.component.TurnSignalLeftRec receive receive.component.TurnSignalLeftRec@1cfb549
class receive.component.TurnSignalLeftRec doReceive receive.component.TurnSignalLeftRec@1cfb549
左转向灯
class order.command.SteeringWheelLeftComm execute order.command.SteeringWheelLeftComm@1820dda
class receive.component.SteeringWheelLeftRec receive receive.component.SteeringWheelLeftRec@15b7986
class receive.component.SteeringWheelLeftRec doReceive receive.component.SteeringWheelLeftRec@15b7986
左打方向盘
class order.command.BrakeComm execute order.command.BrakeComm@112f614
class receive.component.BrakeRec receive receive.component.BrakeRec@1d9dc39
class receive.component.BrakeRec doReceive receive.component.BrakeRec@1d9dc39
刹车
class order.command.IgnitionComm execute order.command.IgnitionComm@111a3ac
class receive.component.IgnitionRec receive receive.component.IgnitionRec@110b053
class receive.component.IgnitionRec doReceive receive.component.IgnitionRec@110b053
点火
class order.command.ClutchComm execute order.command.ClutchComm@19efb05
class receive.component.ClutchRec receive receive.component.ClutchRec@723d7c
class receive.component.ClutchRec doReceive receive.component.ClutchRec@723d7c
离合
class order.command.HangOutComm execute order.command.HangOutComm@a981ca
class receive.component.HangOutRec receive receive.component.HangOutRec@8814e9
class receive.component.HangOutRec doReceive receive.component.HangOutRec@8814e9
挂挡
class order.command.OilComm execute order.command.OilComm@743399
class receive.component.OilRec receive receive.component.OilRec@e7b241
class receive.component.OilRec doReceive receive.component.OilRec@e7b241
给油
执行命令----加速
class receive.car.impl.CarAddRec receive receive.car.impl.CarAddRec@1d8957f
receive.car.impl.CarAddRec doReceive class receive.car.impl.CarAddRec
class order.step.impl.CarAddComm execute order.step.impl.CarAddComm@3ee284
class order.command.OilComm execute order.command.OilComm@743399
class receive.component.OilRec receive receive.component.OilRec@e7b241
class receive.component.OilRec doReceive receive.component.OilRec@e7b241
给油
class order.command.ClutchComm execute order.command.ClutchComm@19efb05
class receive.component.ClutchRec receive receive.component.ClutchRec@723d7c
class receive.component.ClutchRec doReceive receive.component.ClutchRec@723d7c
离合
class order.command.HangOutComm execute order.command.HangOutComm@a981ca
class receive.component.HangOutRec receive receive.component.HangOutRec@8814e9
class receive.component.HangOutRec doReceive receive.component.HangOutRec@8814e9
挂挡
class order.command.OilComm execute order.command.OilComm@743399
class receive.component.OilRec receive receive.component.OilRec@e7b241
class receive.component.OilRec doReceive receive.component.OilRec@e7b241
给油
5.2.7 说明
这里命令的集合的实现不能放在享元的工厂中，虽然命令与命令的集合都实现了命令的接口，理论上把命令的集合放在享元的工厂中也不会报错。但是会有执行错误。
原因就是命令的集合在调用命令时的方法：
@Override
public void execute() {
System.out.println(this.getClass() + "\texecute\t"
+ this);
IntfCommand command = step.poll();
while(command != null){
command.execute();
command = step.poll();
}
}
可以看到使用的是队列的弹出方法，这个方法具有两个操作：
1.返回队列头部的元素
2.删除当前队列头部的元素，并把头指向下一个元素
也就是说上面的这个方法破坏了数据，无法作为享元工厂的元数据。
那么必须要使用享元提高性能怎么办？
那就在上一层：我们这里的操作是起步，加速这一类的操作，更高一层的操作就是以起步，加速的操作作为原子操作的级别，在这一级别的享元工厂可以把起步、加速作为元数据。
但是命令的发动者的角色可以放在享元的工厂中：
因为发动者的方法没有破坏数据：
@Override
protected void doReceive() {
System.out.println(this.getClass().getName() + "\tdoReceive\t"
+ this.getClass());
carStart.execute();
}
只是调用方法。