设计模式 Concurrency 之 Balking 慢行模式

短命女 2022-06-10 03:15 113阅读 0赞

*  定义
 *  例子

# 1.定义 #

当现在不适合这个操作，或者没有必要进行这个操作时，就直接放弃而回去

# 2.例子 #

![这里写图片描述][SouthEast]

WashinMachineState

package com.hqq.concurrency.balking;
    
    /** * WashingMachineState * Created by heqianqian on 2017/7/30. */
    public enum WashingMachineState {
    
        ENABLED, WASHING;
    
    }

WashingMachine

package com.hqq.concurrency.balking;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    
    /** * WashingMachine * Created by heqianqian on 2017/7/30. */
    public class WashingMachine { 
    
        private static final Logger LOGGER = LoggerFactory.getLogger(WashingMachine.class);
    
        private WashingMachineState washingMachineState;
    
        public WashingMachine() {
            this.washingMachineState = WashingMachineState.ENABLED;
        }
    
        public void wash() {
            synchronized (this) {
                if (washingMachineState == WashingMachineState.WASHING) {
                    LOGGER.info("{}: Error:Machine is Running");
                    return;
                }
                washingMachineState = WashingMachineState.WASHING;
            }
            LOGGER.info("{} is Washing..", Thread.currentThread().getName());
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            endOfWashing();
        }
    
        private synchronized void endOfWashing() {
            LOGGER.info("{} Finished Washing", Thread.currentThread().getName());
            washingMachineState = WashingMachineState.ENABLED;
        }
    
        public WashingMachineState getWashingMachineState() {
            return washingMachineState;
        }
    }

APP

package com.hqq.concurrency.balking;
    
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    
    /** * App * Created by heqianqian on 2017/7/30. */
    public class App { 
    
        public static void main(String... args) {
            final WashingMachine washingMachine = new WashingMachine();
            ExecutorService executorService = Executors.newFixedThreadPool(3);
            executorService.execute(washingMachine::wash);
            executorService.execute(washingMachine::wash);
            executorService.execute(washingMachine::wash);
            executorService.shutdown();
        }
    }

测试结果：

INFO  [2017-08-09 01:17:56,169] com.hqq.concurrency.balking.WashingMachine: {}: Error:Machine is Running
    INFO  [2017-08-09 01:17:56,169] com.hqq.concurrency.balking.WashingMachine: pool-1-thread-1 is Washing..
    INFO  [2017-08-09 01:17:56,169] com.hqq.concurrency.balking.WashingMachine: {}: Error:Machine is Runningcom.hqq.concurrency.balking.WashingMachine: pool-1-thread-1 Finished Washing

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[SouthEast]: /images/20220610/d2f79a7a5e4f4b1a86294a1485b39705.png