[圖解Java]Condition

時間 2019-12-07

標籤圖解 java condition 欄目 Java 简体版

原文原文鏈接

圖解Condition

0. demo

我先給出一個demo, 這樣你們就能夠根據我給的這段代碼, 邊調試邊看源碼了. 仍是那句話: 注意"My" , 我把ReentrantLock類更名爲了 "MyReentrantLock"類 , "Lock"類更名爲了"MyLock"類. 你們粘貼個人代碼的時候, 把相應的"My"都去掉就行了, 不然會編譯報錯哦.java

import java.util.Scanner;
import java.util.concurrent.locks.Condition;
import java.util.function.Supplier;

public class ConditionTest {
    static final Scanner scanner = new Scanner(System.in);
    static volatile String cmd = "";
    private static MyReentrantLock lock = new MyReentrantLock(true);
    private static Condition condition = lock.newCondition();

    public static void main(String[] args) {
        for (String name : new String[]{"w1", "w2", "w3", "w4", "w5", "w6"})
            new Thread(() -> func(() -> lock, name)).start();
        new Thread(() -> signalOne(() -> lock, "s")).start();

        while (scanner.hasNext()) {
            cmd = scanner.nextLine();
        }
    }

    public static void func(Supplier<MyLock> myLockSupplier, String name) {
        blockUntilEquals(() -> cmd, name);
        myLockSupplier.get().lock();

        System.out.println(name + "阻塞等待...");
        try {
            condition.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("釋放了" + name);

        myLockSupplier.get().unlock();
    }

    public static void signalOne(Supplier<MyLock> myLockSupplier, String name) {
        while (true) {
            blockUntilEquals(() -> cmd, name);
            myLockSupplier.get().lock();
            condition.signal();
            System.out.println("通知喚醒了一個等待...");
            myLockSupplier.get().unlock();
        }
    }

    private static void blockUntilEquals(Supplier<String> cmdSupplier, final String expect) {
        while (!cmdSupplier.get().equals(expect))
            quietSleep(1000);
        clearCmd();
    }

    private static void quietSleep(int mills) {
        try {
            Thread.sleep(mills);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    private static void clearCmd() {
        cmd = "";
    }
}

使用例子在下面. ui

首先輸入w1, 讓線程1執行await() . 而後輸入w2, 讓線程2執行await(). 而後輸入w3, 讓線程3執行await().線程

接下來輸入3次 s, 沒輸入一次s, 並按下回車, 就會signal通知一個await等待.3d