actionlistenerinstaller.java

此文档包含有AOP

package test.annotation.coreTest;

import java.awt.event.*;
import java.lang.annotation.*;
import java.lang.reflect.*;

public class ActionListenerInstaller
{
    /**
       Processes all ActionListenerFor annotations in the given object.
      @param obj an object whose methods may have ActionListenerFor annotations
    */
    public static void processAnnotations(Object obj)
    {
       try
       {
          Class cl = obj.getClass();
          for (Method m : cl.getDeclaredMethods())
          {
             ActionListenerFor a = m.getAnnotation(ActionListenerFor.class);
             if (a != null)
             {
                Field f = cl.getDeclaredField(a.source());
                f.setAccessible(true);
                addListener(f.get(obj), obj, m);
             }
          }
       }
       catch (Exception e)
       {
          e.printStackTrace();
       }
    }

    /**
       Adds an action listener that calls a given method.
       @param source the event source to which an action listener is added
       @param param the implicit parameter of the method that the listener calls
       @param m the method that the listener calls
    */
    public static void addListener(Object source, final Object param, final Method m)
       throws NoSuchMethodException, IllegalAccessException, InvocationTargetException
    {
       InvocationHandler handler = new
          InvocationHandler()
          {
             public Object invoke(Object proxy, Method mm, Object[] args) throws Throwable
             {
                return m.invoke(param);
             }
          };

       Object listener = Proxy.newProxyInstance(null,
          new Class[] { java.awt.event.ActionListener.class },
          handler);
       Method adder = source.getClass().getMethod("addActionListener", ActionListener
.class);
       adder.invoke(source, listener);
    }
 }