rue;
} catch (Throwable ex) {
//出现异常 封装到FutureTask
result = null;
ran = false;
setException(ex);
}
//..
}
等到执行get时，先阻塞、直到完成任务再来判断状态，如果状态不正常则抛出封装的异常
private V report(int s) throws ExecutionException {
Object x = outcome;
if (s == NORMAL)
return (V)x;
if (s >= CANCELLED)
throw new CancellationException();
throw new ExecutionException((Throwable)x);
}
因此在处理Callable任务时，可以对任务进行捕获也可以对get进行捕获
//捕获任务
Future<?> f = threadPool.submit(() -> {
try {
int i = 1;
int j = 0;
return i / j;
} catch (Exception e) {
System.out.println(e);
} finally {
return null;
}
});
?
//捕获get
Future<Integer> future = threadPool.submit(() -> {
int i = 1;
int j = 0;
return i / j;
});
?
try {
Integer integer = future.get();
} catch (Exception e) {
System.out.println(e);
}
afterExecutor
还记得线程池的runWorker吗？
它在循环中不停的获取阻塞队列中的任务执行，在执行前后预留钩子方法
继承ThreadPoolExecutor来重写执行后的钩子方法，记录执行完是否发生异常，如果有异常则进行日志记录，作一层兜底方案
public class MyThreadPool extends ThreadPoolExecutor {
//...
@Override
protected void afterExecute(Runnable r, Throwable t) {
//Throwable为空 可能是submit提交 如果runnable为future 则捕获get
if (Objects.isNull(t) && r instanceof Future<?>) {
try {
Object res = ((Future<?>) r).get();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
} catch (ExecutionException e) {
t = e;
}
}
?
if (Objects.nonNul