java - java.lang.reflect.InitationHandler 的调用方法参数列表中的 "proxy"对象代表什么？

Question

我对这种情况有点困惑:

我有一个类，它实现了标题中提到的 InvocableHandler 接口(interface)，该类如下所示:

class SimpleProxy implements InvocationHandler{
    
    private Object proxied;
    
    public SimpleProxy(Object proxied) {
        this.proxied = proxied;
    }
    
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        
        System.out.println(proxy);
        return method.invoke(proxied, args);
        
    }
    
}

并且可以说在我的“主要”方法中我有:

public static void main(String[] args) {
        
        consumer(new RealObject());
        
        MyInterface proxy = (MyInterface)Proxy.newProxyInstance(MainClass.class.getClassLoader(), new Class[]{MyInterface.class}, new SimpleProxy(new MyInterfaceImpl()));
        
        proxy.methodFromMyInterface();
        
    }

现在的问题是“invoke”抛出如下错误:

...

at rtti.SimpleProxy.invoke(MainClass.java:81)

at rtti.$Proxy0.toString(Unknown Source)

at java.lang.String.valueOf(String.java:2826)

at java.io.PrintStream.println(PrintStream.java:771)

at rtti.SimpleProxy.invoke(MainClass.java:81)

at rtti.$Proxy0.toString(Unknown Source)

at java.lang.String.valueOf(String.java:2826)

at java.io.PrintStream.println(PrintStream.java:771)

...

因为这一行:

System.out.println(proxy);

如果我评论这一行，一切都会正常。

谁能帮我解释一下这是什么问题吗？

注意在 Java 文档中，它介绍了 InvocableHandler 的调用方法:

Processes a method invocation on a proxy instance and returns the result. This method will be invoked on an invocation handler when a method is invoked on a proxy instance that it is associated with.

Parameters:proxy - the proxy instance that the method was invoked on

...所以我不明白为什么会出错...

Answer 1

System.out.println(proxy); 将隐式调用代理上的 toString()，即调用代理方法。