行为型之命令模式

命令模式将"行为请求者与行为实现者进行解耦"

在请求和实现之间加一中间层

如实现四则运算例子

//运算接口ICommand.java

package demo;

public interface ICommand {
  public void handle(int num1,int num2);
}
//实现运算Mul.java

package demo;

public class Mul implements ICommand {

 public void handle(int num1,int num2) {
  System.out.print(num1*num2);
  System.out.println();
 }
}

//Plus.java

package demo;

public class Plus implements ICommand {

 public  void handle(int num1,int num2) {
  System.out.print(num1+num2);
  System.out.println();
 }
}

//Mul.java

package demo;

public class Mul implements ICommand {
 public void handle(int num1,int num2) {
  System.out.print(num1*num2);
  System.out.println();
 }
}

//Sub.java

package demo;

public class Sub implements ICommand {

 public void handle(int num1,int num2) {
  System.out.print(num1-num2);
  System.out.println();
 }

}
//中间层,命令层

package demo;
import java.util.HashMap;
import java.util.Map;
public class Commands {
 // 命令模式的中间层，完成接收命令，统一执行
 private Map map;

 public Commands() {
  map = new HashMap();
  addCommand("1", new Plus());
  addCommand("2", new Sub());
  addCommand("3", new Mul());
 }

 public void addCommand(String cmdId, ICommand cmd) { 用来收集命令
  map.put(cmdId, cmd);
 }

 public void doRequest(String cmdId,int num1,int num2) {
  //统一执行的方法
  ICommand cmd = (ICommand)map.get(cmdId);
  cmd.handle(num1,num2);
 }

}
//调用TestMain.java

package demo;

public class testMain {
 public static void main(String[] args) {
  Commands cmds = new Commands();
  cmds.doRequest("1", 100,5);
  cmds.doRequest("2", 100,5);
  cmds.doRequest("3", 100,5);
 }
}