HeadFirst设计模式之命令模式
一、
1.因为是操作经常变化，所以封装操作为command对象。You can do that by introducing “command objects” into your design. A command object encapsulates a request to do something (like turn on a light) on a specific object (say, the living room light object). So, if we store a command object for each button, when the button is pressed we ask the command object to do some work. The remote doesn’t have any idea what the work is, it just has a command object that knows how to talk to the right object to get the work done.So, you see, the remote is decoupled from the light object!
2.The Command Pattern encapsulates a request as an object, thereby letting you parameterize other objects
with different requests, queue or log requests, and support undoable operations.
3.When you need to decouple an object making requests from the objects that know how to perform the requests, use
the Command Pattern.
3.
4.
5.
6.
7.
8.
二、简单命令模式
1.
package headfirst.designpatterns.command.simpleremote;
public interface Command {
public void execute();
}
2.
package headfirst.designpatterns.command.simpleremote;
public class LightOnCommand implements Command {
Light light;
public LightOnCommand(Light light) {
this.light = light;
}
public void execute() {
light.on();
}
}
3.
package headfirst.designpatterns.command.simpleremote;
public class Light {
public Light() {
}
public void on() {
System.out.println("Light is on");
}
public void off() {
System.out.println("Light is off");
}
}
4.
package headfirst.designpatterns.command.simpleremote; //
// This is the invoker
//
public class SimpleRemoteControl {
Command slot; public SimpleRemoteControl() {} public void setCommand(Command command) {
slot = command;
} public void buttonWasPressed() {
slot.execute();
}
}
5.
package headfirst.designpatterns.command.simpleremote;
public class RemoteControlTest {
public static void main(String[] args) {
SimpleRemoteControl remote = new SimpleRemoteControl();
Light light = new Light();
GarageDoor garageDoor = new GarageDoor();
LightOnCommand lightOn = new LightOnCommand(light);
GarageDoorOpenCommand garageOpen =
new GarageDoorOpenCommand(garageDoor);
remote.setCommand(lightOn);
remote.buttonWasPressed();
remote.setCommand(garageOpen);
remote.buttonWasPressed();
}
}
三、远程调用命令模式
1.
package headfirst.designpatterns.command.remote;
public class RemoteLoader {
public static void main(String[] args) {
RemoteControl remoteControl = new RemoteControl();
Light livingRoomLight = new Light("Living Room");
Light kitchenLight = new Light("Kitchen");
CeilingFan ceilingFan= new CeilingFan("Living Room");
GarageDoor garageDoor = new GarageDoor("");
Stereo stereo = new Stereo("Living Room");
LightOnCommand livingRoomLightOn =
new LightOnCommand(livingRoomLight);
LightOffCommand livingRoomLightOff =
new LightOffCommand(livingRoomLight);
LightOnCommand kitchenLightOn =
new LightOnCommand(kitchenLight);
LightOffCommand kitchenLightOff =
new LightOffCommand(kitchenLight);
CeilingFanOnCommand ceilingFanOn =
new CeilingFanOnCommand(ceilingFan);
CeilingFanOffCommand ceilingFanOff =
new CeilingFanOffCommand(ceilingFan);
GarageDoorUpCommand garageDoorUp =
new GarageDoorUpCommand(garageDoor);
GarageDoorDownCommand garageDoorDown =
new GarageDoorDownCommand(garageDoor);
StereoOnWithCDCommand stereoOnWithCD =
new StereoOnWithCDCommand(stereo);
StereoOffCommand stereoOff =
new StereoOffCommand(stereo);
remoteControl.setCommand(0, livingRoomLightOn, livingRoomLightOff);
remoteControl.setCommand(1, kitchenLightOn, kitchenLightOff);
remoteControl.setCommand(2, ceilingFanOn, ceilingFanOff);
remoteControl.setCommand(3, stereoOnWithCD, stereoOff);
System.out.println(remoteControl);
remoteControl.onButtonWasPushed(0);
remoteControl.offButtonWasPushed(0);
remoteControl.onButtonWasPushed(1);
remoteControl.offButtonWasPushed(1);
remoteControl.onButtonWasPushed(2);
remoteControl.offButtonWasPushed(2);
remoteControl.onButtonWasPushed(3);
remoteControl.offButtonWasPushed(3);
}
}
2.
package headfirst.designpatterns.command.remote; //
// This is the invoker
//
public class RemoteControl {
Command[] onCommands;
Command[] offCommands; public RemoteControl() {
onCommands = new Command[7];
offCommands = new Command[7]; Command noCommand = new NoCommand();
for (int i = 0; i < 7; i++) {
onCommands[i] = noCommand;
offCommands[i] = noCommand;
}
} public void setCommand(int slot, Command onCommand, Command offCommand) {
onCommands[slot] = onCommand;
offCommands[slot] = offCommand;
} public void onButtonWasPushed(int slot) {
onCommands[slot].execute();
} public void offButtonWasPushed(int slot) {
offCommands[slot].execute();
} public String toString() {
StringBuffer stringBuff = new StringBuffer();
stringBuff.append("\n------ Remote Control -------\n");
for (int i = 0; i < onCommands.length; i++) {
stringBuff.append("[slot " + i + "] " + onCommands[i].getClass().getName()
+ " " + offCommands[i].getClass().getName() + "\n");
}
return stringBuff.toString();
}
}
3.
package headfirst.designpatterns.command.remote;
public class Stereo {
String location;
public Stereo(String location) {
this.location = location;
}
public void on() {
System.out.println(location + " stereo is on");
}
public void off() {
System.out.println(location + " stereo is off");
}
public void setCD() {
System.out.println(location + " stereo is set for CD input");
}
public void setDVD() {
System.out.println(location + " stereo is set for DVD input");
}
public void setRadio() {
System.out.println(location + " stereo is set for Radio");
}
public void setVolume(int volume) {
// code to set the volume
// valid range: 1-11 (after all 11 is better than 10, right?)
System.out.println(location + " Stereo volume set to " + volume);
}
}
4.
package headfirst.designpatterns.command.remote;
public class StereoOnWithCDCommand implements Command {
Stereo stereo;
public StereoOnWithCDCommand(Stereo stereo) {
this.stereo = stereo;
}
public void execute() {
stereo.on();
stereo.setCD();
stereo.setVolume(11);
}
}
5.
四、有undo功能的命令模式
1.
package headfirst.designpatterns.command.undo;
public class RemoteLoader {
public static void main(String[] args) {
RemoteControlWithUndo remoteControl = new RemoteControlWithUndo();
Light livingRoomLight = new Light("Living Room");
LightOnCommand livingRoomLightOn =
new LightOnCommand(livingRoomLight);
LightOffCommand livingRoomLightOff =
new LightOffCommand(livingRoomLight);
remoteControl.setCommand(0, livingRoomLightOn, livingRoomLightOff);
remoteControl.onButtonWasPushed(0);
remoteControl.offButtonWasPushed(0);
System.out.println(remoteControl);
remoteControl.undoButtonWasPushed();
remoteControl.offButtonWasPushed(0);
remoteControl.onButtonWasPushed(0);
System.out.println(remoteControl);
remoteControl.undoButtonWasPushed();
CeilingFan ceilingFan = new CeilingFan("Living Room");
CeilingFanMediumCommand ceilingFanMedium =
new CeilingFanMediumCommand(ceilingFan);
CeilingFanHighCommand ceilingFanHigh =
new CeilingFanHighCommand(ceilingFan);
CeilingFanOffCommand ceilingFanOff =
new CeilingFanOffCommand(ceilingFan);
remoteControl.setCommand(0, ceilingFanMedium, ceilingFanOff);
remoteControl.setCommand(1, ceilingFanHigh, ceilingFanOff);
remoteControl.onButtonWasPushed(0);
remoteControl.offButtonWasPushed(0);
System.out.println(remoteControl);
remoteControl.undoButtonWasPushed();
remoteControl.onButtonWasPushed(1);
System.out.println(remoteControl);
remoteControl.undoButtonWasPushed();
}
}
2.
package headfirst.designpatterns.command.undo; //
// This is the invoker
//
public class RemoteControlWithUndo {
Command[] onCommands;
Command[] offCommands;
Command undoCommand; public RemoteControlWithUndo() {
onCommands = new Command[7];
offCommands = new Command[7]; Command noCommand = new NoCommand();
for(int i=0;i<7;i++) {
onCommands[i] = noCommand;
offCommands[i] = noCommand;
}
undoCommand = noCommand;
} public void setCommand(int slot, Command onCommand, Command offCommand) {
onCommands[slot] = onCommand;
offCommands[slot] = offCommand;
} public void onButtonWasPushed(int slot) {
onCommands[slot].execute();
undoCommand = onCommands[slot];
} public void offButtonWasPushed(int slot) {
offCommands[slot].execute();
undoCommand = offCommands[slot];
} public void undoButtonWasPushed() {
undoCommand.undo();
} public String toString() {
StringBuffer stringBuff = new StringBuffer();
stringBuff.append("\n------ Remote Control -------\n");
for (int i = 0; i < onCommands.length; i++) {
stringBuff.append("[slot " + i + "] " + onCommands[i].getClass().getName()
+ " " + offCommands[i].getClass().getName() + "\n");
}
stringBuff.append("[undo] " + undoCommand.getClass().getName() + "\n");
return stringBuff.toString();
}
}
3.
package headfirst.designpatterns.command.undo;
public class NoCommand implements Command {
public void execute() { }
public void undo() { }
}
4.
package headfirst.designpatterns.command.undo;
public class Light {
String location;
int level;
public Light(String location) {
this.location = location;
}
public void on() {
level = 100;
System.out.println("Light is on");
}
public void off() {
level = 0;
System.out.println("Light is off");
}
public void dim(int level) {
this.level = level;
if (level == 0) {
off();
}
else {
System.out.println("Light is dimmed to " + level + "%");
}
}
public int getLevel() {
return level;
}
}
5.
package headfirst.designpatterns.command.undo;
public class LightOffCommand implements Command {
Light light;
int level;
public LightOffCommand(Light light) {
this.light = light;
}
public void execute() {
level = light.getLevel();
light.off();
}
public void undo() {
light.dim(level);
}
}
6.
package headfirst.designpatterns.command.undo;
public class LightOnCommand implements Command {
Light light;
int level;
public LightOnCommand(Light light) {
this.light = light;
}
public void execute() {
level = light.getLevel();
light.on();
}
public void undo() {
light.dim(level);
}
}
7.
package headfirst.designpatterns.command.undo;
public class CeilingFan {
public static final int HIGH = 3;
public static final int MEDIUM = 2;
public static final int LOW = 1;
public static final int OFF = 0;
String location;
int speed;
public CeilingFan(String location) {
this.location = location;
speed = OFF;
}
public void high() {
speed = HIGH;
System.out.println(location + " ceiling fan is on high");
}
public void medium() {
speed = MEDIUM;
System.out.println(location + " ceiling fan is on medium");
}
public void low() {
speed = LOW;
System.out.println(location + " ceiling fan is on low");
}
public void off() {
speed = OFF;
System.out.println(location + " ceiling fan is off");
}
public int getSpeed() {
return speed;
}
}
8.
package headfirst.designpatterns.command.undo;
public class CeilingFanHighCommand implements Command {
CeilingFan ceilingFan;
int prevSpeed;
public CeilingFanHighCommand(CeilingFan ceilingFan) {
this.ceilingFan = ceilingFan;
}
public void execute() {
prevSpeed = ceilingFan.getSpeed();
ceilingFan.high();
}
public void undo() {
if (prevSpeed == CeilingFan.HIGH) {
ceilingFan.high();
} else if (prevSpeed == CeilingFan.MEDIUM) {
ceilingFan.medium();
} else if (prevSpeed == CeilingFan.LOW) {
ceilingFan.low();
} else if (prevSpeed == CeilingFan.OFF) {
ceilingFan.off();
}
}
}
9.
package headfirst.designpatterns.command.undo;
public class CeilingFanLowCommand implements Command {
CeilingFan ceilingFan;
int prevSpeed;
public CeilingFanLowCommand(CeilingFan ceilingFan) {
this.ceilingFan = ceilingFan;
}
public void execute() {
prevSpeed = ceilingFan.getSpeed();
ceilingFan.low();
}
public void undo() {
if (prevSpeed == CeilingFan.HIGH) {
ceilingFan.high();
} else if (prevSpeed == CeilingFan.MEDIUM) {
ceilingFan.medium();
} else if (prevSpeed == CeilingFan.LOW) {
ceilingFan.low();
} else if (prevSpeed == CeilingFan.OFF) {
ceilingFan.off();
}
}
}
五、全部关或开
1.
package headfirst.designpatterns.command.party;
public class RemoteLoader {
public static void main(String[] args) {
RemoteControl remoteControl = new RemoteControl();
Light light = new Light("Living Room");
TV tv = new TV("Living Room");
Stereo stereo = new Stereo("Living Room");
Hottub hottub = new Hottub();
LightOnCommand lightOn = new LightOnCommand(light);
StereoOnCommand stereoOn = new StereoOnCommand(stereo);
TVOnCommand tvOn = new TVOnCommand(tv);
HottubOnCommand hottubOn = new HottubOnCommand(hottub);
LightOffCommand lightOff = new LightOffCommand(light);
StereoOffCommand stereoOff = new StereoOffCommand(stereo);
TVOffCommand tvOff = new TVOffCommand(tv);
HottubOffCommand hottubOff = new HottubOffCommand(hottub);
Command[] partyOn = { lightOn, stereoOn, tvOn, hottubOn};
Command[] partyOff = { lightOff, stereoOff, tvOff, hottubOff};
MacroCommand partyOnMacro = new MacroCommand(partyOn);
MacroCommand partyOffMacro = new MacroCommand(partyOff);
remoteControl.setCommand(0, partyOnMacro, partyOffMacro);
System.out.println(remoteControl);
System.out.println("--- Pushing Macro On---");
remoteControl.onButtonWasPushed(0);
System.out.println("--- Pushing Macro Off---");
remoteControl.offButtonWasPushed(0);
}
}
2.
package headfirst.designpatterns.command.party;
public class MacroCommand implements Command {
Command[] commands;
public MacroCommand(Command[] commands) {
this.commands = commands;
}
public void execute() {
for (int i = 0; i < commands.length; i++) {
commands[i].execute();
}
}
/**
* NOTE: these commands have to be done backwards to ensure
* proper undo functionality
*/
public void undo() {
for (int i = commands.length -1; i >= 0; i--) {
commands[i].undo();
}
}
}
3.
package headfirst.designpatterns.command.party; //
// This is the invoker
//
public class RemoteControl {
Command[] onCommands;
Command[] offCommands;
Command undoCommand; public RemoteControl() {
onCommands = new Command[7];
offCommands = new Command[7]; Command noCommand = new NoCommand();
for(int i=0;i<7;i++) {
onCommands[i] = noCommand;
offCommands[i] = noCommand;
}
undoCommand = noCommand;
} public void setCommand(int slot, Command onCommand, Command offCommand) {
onCommands[slot] = onCommand;
offCommands[slot] = offCommand;
} public void onButtonWasPushed(int slot) {
onCommands[slot].execute();
undoCommand = onCommands[slot];
} public void offButtonWasPushed(int slot) {
offCommands[slot].execute();
undoCommand = offCommands[slot];
} public void undoButtonWasPushed() {
undoCommand.undo();
} public String toString() {
StringBuffer stringBuff = new StringBuffer();
stringBuff.append("\n------ Remote Control -------\n");
for (int i = 0; i < onCommands.length; i++) {
stringBuff.append("[slot " + i + "] " + onCommands[i].getClass().getName()
+ " " + offCommands[i].getClass().getName() + "\n");
}
stringBuff.append("[undo] " + undoCommand.getClass().getName() + "\n");
return stringBuff.toString();
}
}
4.
package headfirst.designpatterns.command.party;
public class CeilingFanHighCommand implements Command {
CeilingFan ceilingFan;
int prevSpeed;
public CeilingFanHighCommand(CeilingFan ceilingFan) {
this.ceilingFan = ceilingFan;
}
public void execute() {
prevSpeed = ceilingFan.getSpeed();
ceilingFan.high();
}
public void undo() {
switch (prevSpeed) {
case CeilingFan.HIGH: ceilingFan.high(); break;
case CeilingFan.MEDIUM: ceilingFan.medium(); break;
case CeilingFan.LOW: ceilingFan.low(); break;
default: ceilingFan.off(); break;
}
}
}
六、命令模式的其他作用
1.queuing requests
2.logging requests
HeadFirst设计模式之命令模式的更多相关文章
- 设计模式 ( 十三 ) 命令模式Command（对象行为型）
设计模式 ( 十三 ) 命令模式Command(对象行为型) 1.概述 在软件设计中,我们经常需要向某些对象发送请求,但是并不知道请求的接收者是谁,也不知道被请求的操作是哪个,我们只需 ...
- 乐在其中设计模式(C#) - 命令模式(Command Pattern)
原文:乐在其中设计模式(C#) - 命令模式(Command Pattern) [索引页][源码下载] 乐在其中设计模式(C#) - 命令模式(Command Pattern) 作者:webabcd ...
- 面向对象设计模式_命令模式(Command)解读
在.Net框架中很多对象的方法中都会有Invoke方法,这种方法的设计实际是用了设计模式的命令模式, 模式图如下 其核心思路是将Client 向Receiver发送的命令行为进行抽象(ICommand ...
- 折腾Java设计模式之命令模式
博客原文地址 折腾Java设计模式之命令模式 命令模式 wiki上的描述 Encapsulate a request as an object, thereby allowing for the pa ...
- 用Java 8 Lambda表达式实现设计模式：命令模式
在这篇博客里,我将说明如何在使用 Java 8 Lambda表达式 的函数式编程方式 时实现 命令 设计模式 .命令模式的目标是将请求封装成一个对象,从对客户端的不同类型请求,例如队列或日志请求参数化 ...
- python设计模式之命令模式
python设计模式之命令模式 现在多数应用都有撤销操作.虽然难以想象,但在很多年里,任何软件中确实都不存在撤销操作.撤销操作是在1974年引入的,但Fortran和Lisp分别早在1957年和195 ...
- Head First 设计模式 --6 命令模式
命令模式:将"请求"封装成对象,以便使用不同的请求,队列或者日志来参数化其他对象.命令模式也支持可撤销的操作.用到的原则:1.封装变化2.组合优于继承3.针对接口编程,不能针对实现 ...
- C#设计模式(15)——命令模式（Command Pattern）
一.前言 之前一直在忙于工作上的事情,关于设计模式系列一直没更新,最近项目中发现,对于设计模式的了解是必不可少的,当然对于设计模式的应用那更是重要,可以说是否懂得应用设计模式在项目中是衡量一个程序员的 ...
- 【GOF23设计模式】命令模式
来源:http://www.bjsxt.com/ 一.[GOF23设计模式]_命令模式.数据库事务机制底层架构实现.撤销和回复 package com.test.command; public cla ...
随机推荐
- bzoj3405：[Usaco2009 Open]Grazing2 移动牛棚
思路:首先因为要让距离尽量大,所以奶牛1一定在1号牛棚,奶牛n一定在s号牛棚,然后考虑dp. 因为总距离为s-1,然后要使长度为d的段数尽量多,那么剩下的一定就是d+1的段数,也就是s-(n-1)*d ...
- 十天学会零基础入门学习Photoshop课程(在线观看)
适合人群:在校学生 在职工作者 淘宝运营者等一系列会操作电脑的人群 课程目录 试学课 课时11前言 8分钟1秒 课时22工作界面 试学课 课时33文件的新建 试学课 课时44文档保存 11分钟24秒 ...
- <c:forEach>用法
<c:forEach items="${xqsCheckDataList}" var="ch"> <c:if test="${ch. ...
- WinForms 实现气泡提示窗口
[实例说明] 气泡提示因为他的美观又好被大多数用户所接收,用户所喜爱的就是程序员要实现的. 本实例实现了任务栏气泡提示,运行本实例,效果图如下所示: 单击提示.气泡提示就会显示,单击“关闭”气泡又会消 ...
- 关于HTML代码的转义
笔记: 1.在通过jsonp方式传输HTML代码的时候,为了防止代码中的一些字符影响json的语法,需要对HTML代码进行转义. 2.转义的时候可以只转义特殊字符(引号之类的),也可以把所有字符(中文 ...
- 部门招聘开发人员（python相关）
岗位职责: 1.参与需求分析,产品设计,功能开发: 2.负责系统平台的日常维护: 3.与团队技术交流,共同进步 任职要求: 1.精通Python:对Python有兴趣. 2.熟悉MVC架构,精通Dja ...
- Java单例模式--------懒汉式和饿汉式
单件模式用途:单件模式属于工厂模式的特例,只是它不需要输入参数并且始终返回同一对象的引用.单件模式能够保证某一类型对象在系统中的唯一性,即某类在系统中只有一个实例.它的用途十分广泛,打个比方,我们开发 ...
- Pandas简易入门（三）
本节主要介绍一下Pandas的数据结构,本文引用的网址:https://www.dataquest.io/mission/146/pandas-internals-series 本文所使用的数据来自于 ...
- The architecture of LTE network.
3GPP定义的LTE网络架构结构变得扁平化,无线RNC/BSC 消失,只有eNodeB.控制面使用MME进行处理,用户面使用SGW和PGW进行处理.相比GSM和UMTS,在逻辑接口上定义了S1/X2逻 ...
- bootstrap IE兼容
<meta name="viewport" content="width=device-width, initial-scale=1"> & ...