如何为线程组设置 UncaughtExceptionHandler

Question

假设我有 5 个线程属于名为 "Fruits-group" 的线程组。

如何一次性将UncaughtExceptionHandler分配给Fruits-group的所有线程？

我知道我们可以为所有线程定义一个全局 UncaughtExceptionHandler。我正在寻找的是将 UncaughtExceptionHandler 分配给整个线程组？

Answer 1

TL;DR 继承 ThreadGroup 并重写 uncaughtException() 方法。

一个ThreadGroup is an UncaughtExceptionHandler, implementing the uncaughtException(Thread t, Throwable e)方法：

Called by the Java Virtual Machine when a thread in this thread group stops because of an uncaught exception, and the thread does not have a specific Thread.UncaughtExceptionHandler installed.

The uncaughtException method of ThreadGroup does the following:

If this thread group has a parent thread group, the uncaughtException method of that parent is called with the same two arguments.

Otherwise, this method checks to see if there is a default uncaught exception handler installed, and if so, its uncaughtException method is called with the same two arguments.

Otherwise, this method determines if the Throwable argument is an instance of ThreadDeath. If so, nothing special is done. Otherwise, a message containing the thread's name, as returned from the thread's getName method, and a stack backtrace, using the Throwable's printStackTrace method, is printed to the standard error stream.

Applications can override this method in subclasses of ThreadGroup to provide alternative handling of uncaught exceptions.

更新

如果您希望能够为ThreadGroup设置一个UncaughtExceptionHandler，您可以创建一个委托子类：

public class ExceptionHandlingThreadGroup extends ThreadGroup {
    private UncaughtExceptionHandler uncaughtExceptionHandler;
    
    public ExceptionHandlingThreadGroup(String name) {
        super(name);
    }
    public ExceptionHandlingThreadGroup(ThreadGroup parent, String name) {
        super(parent, name);
    }
    
    public UncaughtExceptionHandler getUncaughtExceptionHandler() {
        return this.uncaughtExceptionHandler;
    }
    public void setUncaughtExceptionHandler(UncaughtExceptionHandler uncaughtExceptionHandler) {
        this.uncaughtExceptionHandler = uncaughtExceptionHandler;
    }
    
    @Override
    public void uncaughtException(Thread t, Throwable e) {
        if (this.uncaughtExceptionHandler != null)
            this.uncaughtExceptionHandler.uncaughtException(t, e);
        else
            super.uncaughtException(t, e);
    }
}

虽然，一般来说，直接在子类中实现异常处理逻辑可能会更好，但是这样，您可以使用现有的UncaughtExceptionHandler 实施。

如何为线程组设置 UncaughtExceptionHandler

How to set UncaughtExceptionHandler for a thread group

java

multithreading

threadgroup