HeadFirst设计模式_读书笔记_005_命令模式

命令模式：允许将发出请求的对象和接受并执行这些请求的对象分割开来，即实现请求调用者和请求接受者之间的解耦。定义：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。

 

调用命令的是Invoker,执行命令的实际上是Receiver。通过命令模式，将各种动作封装成Command,实现了Invoker和Receiver的彻底解耦。Invoker只管发出命令，Receiver只管执行相应的操作。

public interface Command {public void execute();}

 

public class Dog {public void foundBone(){System.out.println("找骨头~~");}public void bark(){System.out.println("汪汪~~");}public void sing(){System.out.println("狗狗在唱歌~~");}}

 

public class DogBarkCommand implements Command{private Dog dog;public DogBarkCommand(Dog dog){this.dog = dog;}@Overridepublic void execute() {dog.bark();}}

 

public class DogFoundBoneCommand implements Command {private Dog dog;public DogFoundBoneCommand(Dog dog){this.dog = dog;}@Overridepublic void execute() {dog.foundBone();}}

 

public class DogSingCommand implements Command{private Dog dog;public DogSingCommand(Dog dog){this.dog = dog;}@Overridepublic void execute() {this.dog.sing();}}

 

public class Invoker {Command command;public void setCommand(Command command){this.command = command;}public void invoke(){this.command.execute();}}

 

public class Test {public static void main(String args[]){Dog dog = new Dog();Command barkcommand = new DogBarkCommand(dog);Invoker invoker = new Invoker();invoker.setCommand(barkcommand);invoker.invoke();}}