java - Java 中的动态、反射 SignalHandler

Question

我如何安装信号处理逻辑 iff sun.misc.Signal可用吗？

背景
我的第一代代码假设信号处理可用，看起来像这样:

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

我相信我了解如何反射性地测试和使用信号处理程序 -- Class.forName("sun.misc.Signal") ，反射(reflection)性地调用 Signal.handle ，等等。

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

Answer 1

您需要使用 Dynamic Proxy实现 SignalHandler 接口(interface)。剩下的只是基本的反射(reflection)。

更新

这是你如何做到的。请注意，我省略了需要包装所有这些的 try-catch

        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);