1，命令模式：主要针对需要执行的任务或用户提出的请求进行封装与抽象。抽象的命令接口描述了任务或请求的共同特征，而实现交由不同的具体命令对象完成。每个命令对象都是相互独立的，它负责完成需要执行的任务，却并不关心是谁调用的。
2，UML模型：
3，角色分析：
-1，ICommander：抽象命令者，是一个接口，规定了用来封装请求的若干个方法。
-2，ConcreteCommander：具体命令发送者，即命令源。实现命令接口。
-3，Invoke：请求者，具体命令的管理和维护类。请求者是包含一个“命令接口”变量的实例。请求者调用命令接口，让具体命令执行那些封装的请求方法。
-4，Reciever：命令接受者，是一个类的实例，该实例负责执行与请求相关的操作，
4，代码实例：
package pattern.chp10.commander.simple;/*** 类描述：命令接口** @author: Jing* @version $Id: Exp$** History: Jan 4, 2015 11:07:14 AM Jing Created.**/public interface ICommand {/**** 方法说明：打扫命令** Author： Jing* Create Date： Jan 4, 2015 11:07:36 AM** @return void*/public void sweep();}
package pattern.chp10.commander.simple;/*** 类描述：命令发送者** @author: Jing* @version $Id: Exp$** History: Jan 4, 2015 11:19:09 AM Jing Created.**/public class Teacher implements ICommand{private Student reciever;public Teacher(Student student) {this.reciever = student;}public void sweep() {reciever.sweeping();}}
package pattern.chp10.commander.simple;/*** 类描述：命令接受者，学生** @author: Jing* @version $Id: Exp$** History: Jan 4, 2015 11:07:55 AM Jing Created.**/public class Student {/**** 方法说明：正在打扫** Author： Jing* Create Date： Jan 4, 2015 11:08:36 AM** @return void*/void sweeping(){System.out.println("We are sweeping the floor");}}
package pattern.chp10.commander.simple;/*** 类描述：命令请求者** @author: Jing* @version $Id: Exp$** History: Jan 4, 2015 11:21:03 AM Jing Created.**/public class Invoke {ICommand command;public Invoke(ICommand command) {this.command = command;}public void execute(){command.sweep();}}
package pattern.chp10.commander.simple;/*** 类描述：** @author: Jing* @version $Id: Exp$** History: Jan 4, 2015 2:31:11 PM Jing Created.**/public class MainTest {public static void main(String[] args) {Student s = new Student();ICommand t = new Teacher(s);Invoke invoke = new Invoke(t);invoke.execute();}}
5，深入理解命令模式，命令集管理
假设输入多边形坐标，求取面积，代码如下：
·
package pattern.chp10.commander.area;/*** 类描述：坐标** @author: Jing* @version $Id: Exp$** History: Jan 4, 2015 2:55:20 PM Jing Created.**/public class Point {float x, y;public Point(float x, float y) {this.x = x;this.y = y;}}
package pattern.chp10.commander.area;/*** 类描述：面积计算** @author: Jing* @version $Id: Exp$** History: Jan 4, 2015 2:56:12 PM Jing Created.**/public class PolyonCalc {/**** 方法说明：根据坐标点计算面积** Author： Jing Create Date： Jan 4, 2015 2:56:40 PM** @param pt* @return* @return float*/public float getArea(Point[] pt) {float s = 0;int size = pt.length;if (size < 3) {return s;}s = pt[0].y * (pt[size - 1].x - pt[1].x);for (int i = 1; i < size; i++) {s += pt[i].y * (pt[(i - 1)].x - pt[(i + 1) % size].x);}return (float) s / 2;}}
package pattern.chp10.commander.area;/*** 类描述：命令发送者** @author: Jing* @version $Id: Exp$** History: Jan 4, 2015 3:04:52 PM Jing Created.**/public interface ICommand {/**** 方法说明：计算面积** Author： Jing* Create Date： Jan 4, 2015 3:05:10 PM** @return* @return float*/float calc();}
package pattern.chp10.commander.area;/*** 类描述：具体面积命令发送者** @author: Jing* @version $Id: Exp$** History: Jan 4, 2015 3:05:44 PM Jing Created.**/public class AreaCommander implements ICommand {PolyonCalc calc;Point[] pt;public AreaCommander(PolyonCalc calc, Point[] pt) {this.calc = calc;this.pt = pt;}public float calc() {return calc.getArea(pt);}}
package pattern.chp10.commander.area;import java.util.ArrayList;/*** 类描述：命令管理** @author: Jing* @version $Id: Exp$** History: Jan 4, 2015 3:07:22 PM Jing Created.**/public class CommandManage {ArrayList<ICommand> list = new ArrayList<ICommand>();/**** 方法说明：添加命令** Author： Jing* Create Date： Jan 5, 2015 9:41:32 AM** @param c* @return void*/public void add(ICommand c){list.add(c);}/**** 方法说明：执行命令** Author： Jing* Create Date： Jan 5, 2015 9:41:59 AM** @return void*/public void executeCommand(){for(ICommand command : list){float value = command.calc();System.out.println("The area is : " + value);}}}
package pattern.chp10.commander.area;/*** 类描述：** @author: Jing* @version $Id: Exp$** History: Jan 5, 2015 9:43:15 AM Jing Created.**/public class MainTest {public static void main(String[] args) {CommandManage manage = new CommandManage();PolyonCalc calc = new PolyonCalc();Point[] pt = new Point[3];pt[0] = new Point(0, 0);pt[1] = new Point(1, 0);pt[2] = new Point(0, 1);AreaCommander com = new AreaCommander(calc, pt);manage.add(com);manage.executeCommand();}}
6，命令模式与JDK事件处理：
JDK事件处理机制如图：
-1，事件监听器是保存侦听哪些数据源的容器，技能注册事件源，也能撤销事件源。
-2，当有事件发生的时候，事件监听器遍历监听的数据源容器，判断到底是哪个数据源产生的事件，若能找到，则执行对应的方法。
-3，事件监听是java消息处理机制的核心，由java系统完成。
7，命令模式与多线程：
连续接收字符串信息，并对重要的信息进行提示。
package pattern.chp10.commander.message;/*** 类描述：信息接收功能** @author: Jing* @version $Id: Exp$** History: Jan 5, 2015 10:03:36 AM Jing Created.**/public interface ISource {/**** 方法说明：是否为信息标志** Author： Jing* Create Date： Jan 5, 2015 10:05:13 AM** @return* @return boolean*/boolean isbFire();/**** 方法说明：设置重要信息标志** Author： Jing* Create Date： Jan 5, 2015 10:05:26 AM** @param bFire* @return void*/void setbFire(boolean bFire);}
package pattern.chp10.commander.message;/*** 类描述：信息** @author: Jing* @version $Id: Exp$** History: Jan 5, 2015 10:04:59 AM Jing Created.**/public class Msgsrc implements ISource {String msg;boolean bFire;public String getMsg() {return msg;}public void setMsg(String msg) {this.msg = msg;}public boolean isbFire() {return bFire;}public void setbFire(boolean fire) {this.bFire = fire;}/**** 方法说明：判断消息** Author： Jing* Create Date： Jan 5, 2015 10:08:53 AM** @param msg* @return void*/public void come(String msg){this.msg = msg;if(msg.startsWith("zhang:")){bFire = true;//其他功能代码}}}
package pattern.chp10.commander.message;/*** 类描述：特殊消息处理功能(命令接收者)** @author: Jing* @version $Id: Exp$** History: Jan 5, 2015 10:19:57 AM Jing Created.**/public interface IReceiver {/**** 方法说明：消息处理** Author： Jing* Create Date： Jan 5, 2015 10:20:34 AM** @param src* @return void*/void process(ISource src);}
package pattern.chp10.commander.message;/*** 类描述：具体消息处理类** @author: Jing* @version $Id: Exp$** History: Jan 5, 2015 10:21:02 AM Jing Created.**/public class ShowReceive implements IReceiver {public void process(ISource src) {Msgsrc obj = (Msgsrc) src;System.out.println(obj.getMsg());}}
package pattern.chp10.commander.message;/*** 类描述：Email接受者** @author: Jing* @version $Id: Exp$** History: Jan 5, 2015 10:22:44 AM Jing Created.**/public class EmailReceive implements IReceiver {public void process(ISource src) {System.out.println("This is email receiver,ths msg is : " + ((Msgsrc) src).getMsg());}}
package pattern.chp10.commander.message;/*** 类描述：命令监测功能（相当于Invoke）** @author: Jing* @version $Id: Exp$** History: Jan 5, 2015 10:24:37 AM Jing Created.**/public interface ICommand {/**** 方法说明：消息处理** Author： Jing* Create Date： Jan 5, 2015 10:25:39 AM** @return void*/void noticeCommand();}
package pattern.chp10.commander.message;/*** 类描述：具体命令类** @author: Jing* @version $Id: Exp$** History: Jan 5, 2015 10:34:13 AM Jing Created.**/public class Command implements ICommand {IReceiver rvr;ISource src;public Command(IReceiver rvr, ISource src) {this.rvr = rvr;this.src = src;}public void noticeCommand() {rvr.process(src);}}
package pattern.chp10.commander.message;import java.util.Vector;/*** 类描述：命令管理** @author: Jing* @version $Id: Exp$** History: Jan 5, 2015 10:37:15 AM Jing Created.**/public class CommandManage extends Thread {Vector<ICommand> v = new Vector<ICommand>();ISource src;boolean bMark = true;public CommandManage(ISource src) {this.src = src;}public void addCommand(ICommand c) {v.add(c);}public void run() {while (bMark) {if (!src.isbFire()) {continue;}for (ICommand comm : v) {comm.noticeCommand();}src.setbFire(false);}}}
package pattern.chp10.commander.message;/*** 类描述：** @author: Jing* @version $Id: Exp$** History: Jan 5, 2015 10:55:06 AM Jing Created.**/public class MainTest {public static void main(String[] args) throws Exception {Msgsrc src = new Msgsrc();//定义事件源（发送者）ShowReceive rvr = new ShowReceive();//定义接收者EmailReceive rvr2 = new EmailReceive();Command com = new Command(rvr, src);//定义命令Command com2 = new Command(rvr2, src);//定义命令CommandManage manage = new CommandManage(src);//命令接收集manage.addCommand(com);manage.addCommand(com2);manage.start();String[] s = {"Liu:sdad", "zhang:sdada", "li:sdasdasd"};for(String sTemp: s){src.come(sTemp);Thread.sleep(1000);}manage.bMark = false;}}
时间： 2024-07-31 04:34:44