Java程序可以检测到它的堆空间不足吗？

您可以注册一个javax.management.NotificationListener，当达到某个阈值时调用该方法。

就像是

final MemoryMXBean memBean = ManagementFactory.getMemoryMXBean();final NotificationEmitter ne = (NotificationEmitter) memBean;ne.addNotificationListener(listener, null, null);final List<MemoryPoolMXBean> memPools = ManagementFactory    .getMemoryPoolMXBeans();for (final MemoryPoolMXBean mp : memPools) {  if (mp.isUsageThresholdSupported()) {    final MemoryUsage mu = mp.getUsage();    final long max = mu.getMax();    final long alert = (max * threshold) / 100;    mp.setUsageThreshold(alert);  }}

侦听器是您自己的NotificationListener实现。