对原理类图的说明-即(命名模式的角色及职责)
package com.flower.command;
import lombok.AllArgsConstructor;
import java.util.stream.IntStream;
public class TestMain {
public static void main(String[] args) {
RemoteController facade = CommandFacade.getFacade();
facade.onButtonWasPushed(0);
facade.offButtonWasPushed(0);
facade.undoButtonWasPushed();
}
}
/**
* 命令接口
*/
interface Command {
// 执行
void execute();
// 取消
void undo();
}
@AllArgsConstructor
class LightOnCommand implements Command {
private LightReceiver lightReceiver;
@Override
public void execute() {
lightReceiver.on();
}
@Override
public void undo() {
lightReceiver.off();
}
}
@AllArgsConstructor
class LightOffCommand implements Command {
private LightReceiver lightReceiver;
@Override
public void execute() {
lightReceiver.off();
}
@Override
public void undo() {
lightReceiver.on();
}
}
class LightReceiver {
public void on() {
System.out.println("open the du ang");
}
public void off() {
System.out.println("close the pong");
}
}
/**
* 空命令 用于初始化空命令
*/
class NoCommand implements Command {
@Override
public void execute() {
}
@Override
public void undo() {
}
}
class RemoteController {
// open and close command
private final Command[] onCommands;
private final Command[] offCommands;
// execute undo command
Command undoCommand;
public RemoteController() {
onCommands = new Command[5];
offCommands = new Command[5];
IntStream.range(0, 5).forEach(i -> {
onCommands[i] = new NoCommand();
offCommands[i] = new NoCommand();
});
}
// 设置命令
public void setCommand(int no, Command on, Command off) {
onCommands[no] = on;
offCommands[no] = off;
}
// 执行按钮按下
public void onButtonWasPushed(int no){
onCommands[no].execute();
// 记录按下的操作
undoCommand = onCommands[no];
}
public void offButtonWasPushed(int no){
offCommands[no].execute();
undoCommand = offCommands[no];
}
public void undoButtonWasPushed(){
undoCommand.undo();
}
}
/**
* 为了客户端使用简洁, 可以在命令的外面套用一层外观模式
*/
class CommandFacade{
private static final RemoteController r;
static {
r = new RemoteController();
LightReceiver lightReceiver = new LightReceiver();
r.setCommand(0, new LightOnCommand(lightReceiver),new LightOffCommand(lightReceiver));
}
private CommandFacade(){}
public static RemoteController getFacade() {
return r;
}
}
Spring框架的JdbcTemplate就使用到了命令模式