概述:
UncaughtExceptionHandler是为了捕获没有被捕获的异常,包括运行时异常,执行错误(内存溢出等),子线程抛出的异常等,你可以在uncaughtException(xx)里对后续做处理包括资源释放等
用法:
Runnable实现:
class YourRunable implements Runnable {
public void run() {
throw new RuntimeException("YourRunable");
}
}
UncaughtExceptionHandler实现:
class YourUncaughtExceptionHandler implements UncaughtExceptionHandler {
public void uncaughtException(Thread t, Throwable e) {
System.out.println(t.getName());
System.out.println("*****************");
}
}
测试代码:
public static void main(String[] args) {
Thread.setDefaultUncaughtExceptionHandler(new YourUncaughtExceptionHandler());
try {
Thread yourThread = new Thread(new YourRunable());
yourThread.start();
} catch (Exception e) {
e.printStackTrace();
} try {
throw new RuntimeException("main");
} catch (Exception e) {
e.printStackTrace();
}
throw new RuntimeException("main end");
}
输出:
Thread-0
*****************
java.lang.RuntimeException: main
at org.apache.tools.onest.crawler.nun.TestUncaughtExceptionHandler.main(TestUncaughtExceptionHandler.java:20)
main
*****************
结论:
1.已经被捕获的异常不会被Handler
2.主线程通过Handler来操作子线程产生的异常,而不能直接try catch
3.主线程未被捕获的异常可以在此被Handler
ps:
主线程获取子线程的方式还可以通过子线程的标记位形式来操作,如封装异常类等