Java 中的并发工具类

CountDownLatch

public class JoinCountDownLatchTest {
    public static void main(String[] args) throws InterruptedException {
        Thread parser1 = new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println("parser1 finish!");
            }
        });        Thread parser2 = new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println("parser2 finish!");
            }
        });        parser1.start();
        parser2.start();
        parser1.join();
        parser2.join();
        System.out.println("all parser finish!");
    }
}

运行结果

parser1 finish!

parser2 finish!

all parser finish!

或

parser2 finish!

parser1 finish!

all parser finish!

import java.util.concurrent.CountDownLatch;public class CountDownLatchTest {
    private static CountDownLatch count = new CountDownLatch(2);    public static void main(String[] args) {
        Thread t1 = new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println(1);
                count.countDown();
                System.out.println(2);
                count.countDown();
            }
        });        t1.start();
        try {
            count.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println(3);
    }
}

运行结果

1

2

3

CyclicBarrier

import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;public class CyclicBarrierTest {
    private static CyclicBarrier c = new CyclicBarrier(2);    public static void main(String[] args) {
        Thread t = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    c.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
                System.out.println(1);
            }
        });        t.start();        try {
            c.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (BrokenBarrierException e) {
            e.printStackTrace();
        }
        System.out.println(2);
    }
}

运行结果

1

2

或

2

1

import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;public class CyclicBarrierTest2 {
    private static CyclicBarrier c = new CyclicBarrier(2, new A());    public static void main(String[] args) {
        Thread t = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    c.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
                System.out.println(1);
            }
        });        t.start();
        try {
            c.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (BrokenBarrierException e) {
            e.printStackTrace();
        }
        System.out.println(2);
    }    private static class A implements Runnable {
        @Override
        public void run() {
            System.out.println(3);
        }
    }
}

运行结果

3

1

2

或

3

2

1

import java.util.Map;
import java.util.concurrent.*;public class BankWaterService implements Runnable {
    private CyclicBarrier c = new CyclicBarrier(4, this);
    private ExecutorService executor = Executors.newFixedThreadPool(4);
    private ConcurrentHashMap<String, Integer> sheetBankWaterCount = new ConcurrentHashMap<>();    private void count() {
        for (int i = 0; i < 4; i++) {
            executor.execute(new Runnable() {
                @Override
                public void run() {
                    sheetBankWaterCount.put(Thread.currentThread().getName(), 1);
                    try {
                        c.await();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    } catch (BrokenBarrierException e) {
                        e.printStackTrace();
                    }
                }
            });
        }
        executor.shutdown();
    }    @Override
    public void run() {
        int result = 0;
        for (Map.Entry<String, Integer> sheet : sheetBankWaterCount.entrySet()) {
            result += sheet.getValue();
        }
        sheetBankWaterCount.put("result", result);
        System.out.println(result);
    }    public static void main(String[] args) {
        BankWaterService bankWaterCount = new BankWaterService();
        bankWaterCount.count();
    }
}

运行结果

4

import java.util.concurrent.CyclicBarrier;public class CyclicBarrierTest3 {
    private static CyclicBarrier c = new CyclicBarrier(2);    public static void main(String[] args) throws InterruptedException {
        Thread t = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    c.await();
                } catch (Exception e) {
                }
            }
        });
        t.start();        Thread.sleep(1000);
        System.out.println(c.getNumberWaiting());
        t.interrupt();
        try {
            c.await();
        } catch (Exception e) {
            System.out.println(c.isBroken());
        }
    }
}

运行结果

1

true

Semaphore

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;public class SemaphoreTest {
    private static final int THREAD_COUNT = 30;
    private static ExecutorService executor = Executors.newFixedThreadPool(THREAD_COUNT);
    private static Semaphore s = new Semaphore(10);    public static void main(String[] args) {
        for (int i = 0; i < THREAD_COUNT; i++) {
            executor.execute(new Runnable() {
                @Override
                public void run() {
                    try {
                        s.acquire();
                        System.out.println("save data!");
                        s.release();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            });
        }
        executor.shutdown();
    }
}

Exchanger

import java.util.concurrent.Exchanger;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;public class ExchangerTest {
    private static final Exchanger<String> exgr = new Exchanger<>();
    private static ExecutorService executor = Executors.newFixedThreadPool(2);    public static void main(String[] args) {
        executor.execute(new Runnable() {
            @Override
            public void run() {
                String A = "银行流水 A";
                try {
                    exgr.exchange(A);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });        executor.execute(new Runnable() {
            @Override
            public void run() {
                String B = "银行流水 B";
                try {
                    String A = exgr.exchange(B);
                    System.out.println("A 和 B 数据是否一致：" + A.equals(B) + "，\nA 录入的是：" + A + "，\nB 录入的是：" + B + "。");
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });        executor.shutdown();
    }
}

运行结果

A 和 B 数据是否一致：false，

A 录入的是：银行流水 A，

B 录入的是：银行流水 B。