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package reflection;
public interface HelloWorld {
    void sayHelloWorld();
    void testHello(String hello);
}
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package reflection;
public class HelloWorldImpl implements HelloWorld {
 public void sayHelloWorld() {
  System.out.println("Hello World!");
 }
 
 public void testHello(String hello) {
  System.out.println(hello);
 }
}
3¡¢ÊµÏÖ¶¯Ì¬´úÀíÀ࣬´ËÀà±ØÐëʵÏÖ½Ó¿ÚInvocationHandler£¬ÊµÏÖÏ´½Ó¿ÚµÄ·½·¨
invoke(Object proxy, Method method, Object[] args)
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package reflection;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
public class HelloWorldHandler implements InvocationHandler {
 // Òª´úÀíµÄԭʼ¶ÔÏó
 private Object objOriginal;
 /**
  * ¹¹Ô캯Êý¡£
  * @param obj Òª´úÀíµÄԭʼ¶ÔÏó¡£
  */
 public HelloWorldHandler(Object obj) {
  this.objOriginal = obj;
 }
 public Object invoke(Object proxy, Method method, Object[] args)
   throws Throwable {
  Object result;
  // ·½·¨µ÷ÓÃ֮ǰ
  doBefore();
  // µ÷ÓÃԭʼ¶ÔÏóµÄ·½·¨
  result = method.invoke(this.objOriginal, args);
  // ·½·¨µ÷ÓÃÖ®ºó
  doAfter();
  return result;
 }
 private void doBefore() {
  System.out.println("before method invoke!");
 }
 private void doAfter() {
  System.out.println("after method invoke!");
 }
}
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protected Proxy(InvocationHandler h)£º¹¹Ô캯Êý£¬ÓÃÓÚ¸øÄÚ²¿µÄh¸³Öµ¡£
static Class getProxyClass (ClassLoader loader, Class[] interfaces)£º»ñµÃÒ»¸ö´úÀíÀ࣬ÆäÖÐloaderÊÇÀà×°ÔØÆ÷£¬interfacesÊÇÕæʵÀàËùÓµÓеÄÈ«²¿½Ó¿ÚµÄÊý×é¡£
static Object newProxyInstance(