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前言
UML
plantuml
类图
实战代码
模板
Command
Invoker
Receiver
Client 前言
命令模式解耦了命令请求者#xff08;Invoker#xff09;和命令执行者#xff08;receiver#xff09;#xff0c;使得 Invoker 不再直接引用 receiver#xff0c;而是依赖于…目录
前言
UML
plantuml
类图
实战代码
模板
Command
Invoker
Receiver
Client 前言
命令模式解耦了命令请求者Invoker和命令执行者receiver使得 Invoker 不再直接引用 receiver而是依赖于抽象的命令接口。具体的命令类则直接引用 receiver通过调用 receiver 的方法来执行命令。
解耦之后具体命令的增删改不再影响 Invoker同时抽象出来的命令请求还能队列化从而实现撤销和重试功能或做排列组合合成复杂的命令。
在 Invoker 中也体现了桥接模式的思想将命令的抽象和具体的实现分离使 Invoker 中命令的添加和扩展更加简单。不过具体的命令类并不直接实现处理逻辑而是交给了 receiver 来实现这也是命令模式和桥接模式最主要的区别。
UML
plantuml startuml
https://plantuml.com/class-diagraminterface Command { execute() : void
}class CommandA {- receiver : Receiver CommandA(Receiver) execute() : void
}class CommandB {- receiver : Receiver CommandB(Receiver) execute() : void
}class Receiver { executeA() : void executeB() : void
}class Invoker {- commands : ListCommand addCommand(Command) : void execute(Command) : void executes() : void
}class Client {}Command |.. CommandA
Command |.. CommandBCommandA 1 -- 1 Receiver
CommandB 1 -- 1 ReceiverInvoker 1 -- n CommandClient .. Invoker
Client .. Commandenduml 类图 实战代码
模板
Command
public interface Command {void execute();
}public class ConcreteCommand1 implements Command {private Receiver receiver;public ConcreteCommand1(Receiver receiver) {this.receiver receiver;}public void execute() {receiver.execute1();}
}public class ConcreteCommand2 implements Command {private Receiver receiver;public ConcreteCommand2(Receiver receiver) {this.receiver receiver;}public void execute() {receiver.execute2();}
}Invoker
public class Invoker {private ListCommand commands new ArrayListCommand();public void addCommand(Command command){commands.add(command);}public void execute(Command command){command.execute();}public void executes(){for(Command command : commands){command.execute();}commands.clear();}
}
Receiver
public class Receiver {public void execute1() {System.out.println(execute1.);}public void execute2() {System.out.println(execute2.);}
}
Client
public class Test {public static void main(String[] args) {Receiver receiver new Receiver();Invoker invoker new Invoker();invoker.execute(new Command1(receiver));invoker.addAction(new Command1(receiver));invoker.addAction(new Command2(receiver));invoker.executes();}
}
