动态的，反射的SignalHandler

Question

我如何安装信号处理逻辑当sun.misc.Signal是可用的？

假定信号处理可用的背景第一代代码如下所示：

class MyApp {
    public static void main(String[] args) {
        ...
        Signal.handle(term_sig, new SignalHandler() {
            public void handle(Signal sig) { ... }
        });
        ...
    }
}

我相信我理解如何对信号处理程序进行反射测试和使用-- Class.forName("sun.misc.Signal")、反射调用Signal.handle等等。

我的冲动只是用动态获得的SignalHandler类实例化另一个匿名内部类，但我认为这只是一厢情愿的语法。

Answer 1

您需要使用动态代理来实现SignalHandler接口。其余的只是基本的反映。

更新

这是你怎么做的。注意，我忽略了试图捕获，它需要包装所有这些。

        Class<?> handlerCl = Class.forName("sun.misc.SignalHandler");
        Class<?> signalCl = Class.forName("sun.misc.Signal");

        Constructor signalCtor = signalCl.getConstructor(String.class);
        Method signalHandle = signalCl.getMethod("handle", signalCl, handlerCl);

        // Create a proxy class that implements SignalHandler
        Class<?> proxyClass = Proxy.getProxyClass(signalCl.getClassLoader(),
            handlerCl);

        // This is used by the instance of proxyClass to dispatch method calls
        InvocationHandler invHandler = new InvocationHandler()
        {
            public Object invoke(Object proxy,
                Method method, Object[] args) throws Throwable
            {
                // proxy is the SignalHandler's "this" rederence
                // method will be the handle(Signal) method
                // args[0] will be an instance of Signal
                // If you're using this object for multiple signals, you'll
                // you'll need to use the "getName" method to determine which
                // signal you have caught.
                return null;
            }
        };

        // Get the constructor and create an instance of proxyClass
        Constructor<?> proxyCtor = proxyClass.getConstructor(InvocationHandler.class);
        Object handler = proxyCtor.newInstance(invHandler);

        // Create the signal and call Signal.handle to bind handler to signal
        Object signal = signalCtor.newInstance("TERM");
        signalHandle.invoke(null, signal, handler);