說明

在使用LinkedBlockingQueue的offer方法時，出現了中斷異常，現分析一下出現這個中斷異常的原因。

會產生中斷異常的Demo

import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;

public class TestLinkedBlockingQueue {

    public static void main(String[] args) {
        LinkedBlockingQueue lbq = new LinkedBlockingQueue(3
 
);
        for(int i = 0; i < 10; i++){
            try {
                System.out.println(lbq);
                //這裡用offer方法往阻塞佇列裡面新增物件，此方法表示若佇列滿了，則等待1秒，1秒後若佇列還是滿的，則丟棄資料。
                lbq.offer(i, 1000, TimeUnit.MILLISECONDS);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
 

                e.printStackTrace();
            }
            Thread.currentThread().interrupt();//如果註釋掉這行程式碼，則此程式不會丟擲異常
        }
    }
}

LinkedBlockingQueue的offer原始碼方法

    public boolean offer(E e, long timeout, TimeUnit unit)
        throws InterruptedException {

        if (e == null) throw
 
 new NullPointerException();
        long nanos = unit.toNanos(timeout);
        int c = -1;
        final ReentrantLock putLock = this.putLock;
        final AtomicInteger count = this.count;
        putLock.lockInterruptibly();
        try {
            while (count.get() == capacity) {
                if (nanos <= 0)
                    return false;
                nanos = notFull.awaitNanos(nanos);
            }
            enqueue(new Node<E>(e));
            c = count.getAndIncrement();
            if (c + 1 < capacity)
                notFull.signal();
        } finally {
            putLock.unlock();
        }
        if (c == 0)
            signalNotEmpty();
        return true;
    }


    //lockInterruptibly方法
    public void lockInterruptibly() throws InterruptedException {
        sync.acquireInterruptibly(1);
    }
    //acquireInterruptibly方法
        public final void acquireInterruptibly(int arg)
            throws InterruptedException {
        if (Thread.interrupted())
            throw new InterruptedException();
        if (!tryAcquire(arg))
            doAcquireInterruptibly(arg);
    }

所以，當執行緒被標記有中斷標誌時，offer新增時將獲取不到鎖，直接丟擲中斷異常。