我有一個(gè)異步函數(shù)調(diào)用其他異步函數(shù)。在Java中，如何等到異步調(diào)用完成（包括其中的任何嵌套異步調(diào)用）。我已經(jīng)可以調(diào)用未來(lái)了，但沒(méi)有運(yùn)氣。示例代碼：void asyncMehodA(){ }void asyncMethodB() {asyncMehodA();}我嘗試了未來(lái)可調(diào)用的方式：final Callable<Void> callable1 = new Callable<Void>() { @Override public Void call() { asyncMethodB(); return null; } };final Future<Void> callableFuture = mExecutor.submit(callable1); try { callableFuture.get(); } catch (final InterruptedException | ExecutionException e) {}希望 get 函數(shù)將阻塞執(zhí)行，直到異步返回。但似乎 get 函數(shù)將觸發(fā)異步調(diào)用并恢復(fù) null。而不是等待異步完成其執(zhí)行。我在驗(yàn)證了日志語(yǔ)句中添加了相同的日志語(yǔ)句。如果我的理解是錯(cuò)誤的，請(qǐng)糾正我。建議任何其他可以幫助我的概念。
2 回答
qq_笑_17
TA貢獻(xiàn)1818條經(jīng)驗(yàn) 獲得超7個(gè)贊
下面是一個(gè)使用倒計(jì)時(shí)批處理的示例。
package chapter13;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
public class BST {
public static void main(String[] args) throws InterruptedException {
final CountDownLatch latch = new CountDownLatch(1);
final ExecutorService executorService = Executors.newCachedThreadPool();
Runnable runnableA = () -> {
System.out.println("Runnable A");
latch.countDown();
System.out.println("Runnable A finished");
};
Runnable runnableB = () -> {
System.out.println("Runnable B");
executorService.submit(runnableA);
try {
System.out.println("Runnable B waiting for A to complete");
latch.await();
System.out.println("Runnable B finished");
} catch (InterruptedException e) {
System.out.println("Thread interrupted");
Thread.currentThread().interrupt();
}
};
executorService.submit(runnableB);
Thread.sleep(10);
shutDown(executorService);
}
private static void shutDown(ExecutorService executorService) {
executorService.shutdown();
try {
if (!executorService.awaitTermination(1, TimeUnit.SECONDS)) {
executorService.shutdownNow();
}
} catch (InterruptedException e) {
executorService.shutdownNow();
}
}
}
我使用方法使主線(xiàn)程休眠，因?yàn)樵谔峤蝗蝿?wù) B 后立即關(guān)閉池可能會(huì)導(dǎo)致池在任務(wù) B 提交任務(wù) A 之前停止接受新任務(wù)。Thread.sleep()
DIEA
TA貢獻(xiàn)1820條經(jīng)驗(yàn) 獲得超3個(gè)贊
一種方法是使用java鎖定方法。例如：
private AtomicBoolean processed = new AtomicBoolean(true) ;
private String result = null ;
public String doAndWait()
{
synchronized(processed) {
doSomethingAsync() ;
processed.wait();
}
return result ;
}
public void doSomethingAsync()
{
...
result="OK";
synchronized(processed) {
processed.notify();
}
}
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