我有一个 SwingWorker,它启动一个 LinkedBlockingQueue,将它传递给另一个方法(下面的 PortalDriver),然后在 doInBackground() 方法中读取它。 LinkedBlockingQueue 持有自定义对象的 future (并且它肯定被正确填充)。作为检查,我正在创建的对象(通过 ExecutorService)在构造函数的末尾有一个 println(this),所以我知道它们何时被创建。
问题是,通过 println() 调用(在 doInBackground 和构造函数中),在 doInBackground 的 while 循环中多次成功迭代后,行
System.out.println("future.isDone before get(): " + futureListing.isDone());
打印 true,即使构造函数没有打印它已被创建(这仅通过计数就很清楚)。 while 循环永久阻塞,即使其余对象已创建。
private class ReadSchedWorker extends SwingWorker<Void, Listing> {
private ChromeOptions options = new ChromeOptions();
private WebDriver driver;
private LinkedBlockingQueue<Future<Listing>> listingQueue;
private LoginFactory loginFactory;
private int year;
private int month;
private int day;
public ReadSchedWorker(Login mediasiteLogin, Login tmsLogin,
int year, int month, int day) {
System.setProperty("webdriver.chrome.driver", "\\\\private\\Home\\Desktop\\chromedriver.exe");
listingQueue = new LinkedBlockingQueue<>();
loginFactory = new LoginFactory(mediasiteLogin, tmsLogin);
this.year = year;
this.month = month;
this.day = day;
}
@Override
protected Void doInBackground() throws Exception {
this.options.addArguments("--disable-extensions");
driver = new ChromeDriver(options);
String portalUsername = loginFactory.getPortalUsername();
String portalPassword = loginFactory.getPortalPassword();
PortalDriver portalDriver = new PortalDriver(driver, listingQueue);
portalDriver.getScheduleElements(portalUsername, portalPassword, year, month, day);
while (!listingQueue.isEmpty()) {
System.out.println("beginning");
Future<Listing> futureListing = listingQueue.take();
System.out.println("future.isDone before get(): " + futureListing.isDone());
Listing listing = futureListing.get();
System.out.println("future.isDone after get(): " + futureListing.isDone());
System.out.println("before publish");
publish(listing);
System.out.println("after publish");
}
return null;
}
@Override
protected void process(List<Listing> listings) {
for (Listing listingItem : listings) {
listingListModel.addElement(listingItem);
}
}
}
只是为了完成,这里是 getScheduleElements,它填充了 LinkedBlockingQueue:
public void getScheduleElements(String username, String password, int year, int month, int day) {
driver.get("https://rxsecure.umaryland.edu/apps/schedules/view/?type=search&searchtype=resource&id=100&start=" +
year + "-" + month + "-" + day + "&scope=week");
PortalLoginPage loginPage = PageFactory.initElements(driver, PortalLoginPage.class);
PortalScheduleEventsWeekPage scheduleEventsWeekPage = loginPage.login(username, password);
webElementsQueue = scheduleEventsWeekPage.initEventsQueue();
// doesn't need to be a queue...
// this is sequential....
// could do a parallel stream
while (webElementsQueue.peek() != null) {
Callable<Listing> callable = new PortalListingCallable(webElementsQueue.poll());
Future<Listing> future = executor.submit(callable);
listingQueue.offer(future);
}
executor.shutdown();
}
编辑: 我的意思的一个例子( future 没有完成,但通过 doInBackground() 中的 println()s 报告它是):
beginning
future.isDone before get(): true //the future says it done, but the object being created is below
in listing contructor: PHAR580 Pharmacy Law;Specialty Pharmacy 2;Recorded in Mediasite PH S201 2015-04-27T10:00:00.000-04:00 2015-04-27T11:50:00.000-04:00
最佳答案
prints true, even though the constructor hasn't printed that it has been created
很可能您收到了您没有看到的异常或错误。您必须调用 Future.get() 才能看到它。
同时我建议你改变
Future<Listing> future = executor.submit(callable);
到
Future<Listing> future = executor.submit(new Callable<Listing>() {
public Listing call() throws Throwable {
try {
return callable.call();
} catch (Throwable t) {
t.printStackTrace();
throw t;
}
}
});
关于Java Future.isDone 返回 true,即使它不应该返回 true,这会停止程序进程,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/30674020/