JAVA设计模式之【命令模式】

命令模式    为了降低耦合度，将请求的发送者和接收者解耦    发送请求的对象只需要哦知道如何发送请求，而不必知道如何完成请求    对请求排队    记录请求日志    支持撤销操作    核心在于引入命令类    角色        抽象命令类Command        具体命令类ConcreteCommand        调用者Invoker        接收者Receiver    请求的一方不必知道接收请求的一方，更不必知道请求如何被接收、执行、怎么执行、何时执行

package Command;

/**
* Created by Jiqing on 2016/10/26.
*/
public interface AbstractCommand {
public void execute();
}

package Command;

/**
* Created by Jiqing on 2016/10/26.
*/
public class Television {
public void open() {
System.out.println("打开电视机");
}

public void close() {
System.out.println("关闭电视机");
}

public void changeChannel() {
System.out.println("切换电视频道");
}
}

package Command;

/**
* Created by Jiqing on 2016/10/26.
*/
public class TVOpenCommand implements AbstractCommand{
private Television tv;
public TVOpenCommand() {
tv = new Television();
}

public void execute() {
tv.open();
}
}

package Command;

/**
* Created by Jiqing on 2016/10/26.
*/
public class TVCloseCommand implements AbstractCommand{
private Television tv;
public TVCloseCommand() {
tv = new Television();
}

public void execute() {
tv.close();
}
}

package Command;

/**
* Created by Jiqing on 2016/10/26.
*/
public class TVChangeCommand implements AbstractCommand{
private Television tv;
public TVChangeCommand() {
tv = new Television();
}

public void execute() {
tv.changeChannel();
}
}

package Command;

/**
* Created by Jiqing on 2016/10/26.
*/
public class Controller {
private AbstractCommand openCommand,closeCommand,changeCommand;
public Controller(AbstractCommand openCommand,AbstractCommand closeCommand,AbstractCommand changeCommand) {
this.openCommand = openCommand;
this.closeCommand = closeCommand;
this.changeCommand = changeCommand;
}

public void open() {
openCommand.execute();
}

public void change() {
changeCommand.execute();
}

public void close() {
closeCommand.execute();
}
}

package Command;

/**
* Created by Jiqing on 2016/10/26.
*/
public class Client {
public static void main(String a[]) {
AbstractCommand openCommand,closeCommand,changeCommand;

openCommand = new TVOpenCommand();
closeCommand = new TVCloseCommand();
changeCommand = new TVChangeCommand();

Controller control = new Controller(openCommand,closeCommand,changeCommand);

control.open();
control.close();
control.change();
}
}

package Command.Undo;
abstract class AbstractCommand
{
public abstract int execute(int value);
public abstract int undo();
}

class ConcreteCommand extends AbstractCommand
{
private Adder adder = new Adder();
private int value;

public int execute(int value)
{
this.value=value;
return adder.add(value);
}

public int undo()
{
return adder.add(-value);
}
}

class CalculatorForm
{
private AbstractCommand command;

public void setCommand(AbstractCommand command)
{
this.command=command;
}

public void compute(int value)
{
int i = command.execute(value);
System.out.println("执行运算，运算结果为：" + i);
}

public void undo()
{
int i = command.undo();
System.out.println("执行撤销，运算结果为：" + i);
}
}

class Adder
{
private int num=0;

public int add(int value)
{
num+=value;
return num;
}
}

class Client
{
public static void main(String args[])
{
CalculatorForm form = new CalculatorForm();
ConcreteCommand command = new ConcreteCommand();
form.setCommand(command);

form.compute(10);
form.compute(5);
form.compute(10);
form.undo();
}
}