自定義一個介面 和一個接實現類

public interface Hello {
    void setInfo(String a,String b);
    String getInfo();
    void hah(String s);
}

/**
 * Created by likailong on 2016/9/29.
 */
public class HelloIml implements Hello {
    private String a;
    private String b;
    public void setInfo(String a, String b){
        this.a=a;
        this.b=b;
    }
    @Override
    public String getInfo() {
        return a;
    }

    public void hah(String s){
        System.out.print("ssss"+s);
    }
}
 

package cn.itcast.shujujiegou.StructuresAnalysis;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;

/**
 * Created by likailong on 2016/9/29.
 */
public class AopHandler implements InvocationHandler {
    private Object target;
    public AopHandler(Object target){
        this.target=target;
    }
    public void println(String str,Object...args){
        System.out.println(str);
        if(args==null){
            System.out.println("沒有傳遞任何值");
        }else{
            for(Object obj:args){
                System.out.println(obj);
            }
        }
    }
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("\n\n======呼叫方法名"+method.getName());
        Class<?>[] variables=method.getParameterTypes();
        System.out.println("\n\t 引數列表：\n");
        for(Class<?> typevariables:variables){
            System.out.println("\t\t\t"+typevariables.getName());
        }
        println("\n\n\t 傳入引數值為：\n");
        for(Object arg:args){
            System.out.println("\t\t\t"+arg);
        }
        Object result=method.invoke(target,args);
        println("返回的引數為",result);
        println("返回的型別為",method.getReturnType());
        return result;
    }
}
 

public class MethodInvokeSample {
    public static void main(String [] args) throws Exception {
        Method method=MethodInvokeSample.class.getDeclaredMethod("test",String.class,int.class);
        String result=(String)method.invoke(null,"fuck",21);
        System.out.println(result);
    }
    public static String test(String a,int b){
        return "傳入引數："+a+"傳入引數："+b;
    }
}
 

動態將方法執行並且傳入引數。但是上面沒有展現出面向切面只是動態傳入了一個值下面自定義BeanFactory

package cn.itcast.shujujiegou.StructuresAnalysis;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Proxy;

/**
 * Created by likailong on 2016/9/29.
 */
public class BeanFactory {
    public static Object getBean(String classname) throws ClassNotFoundException, IllegalAccessException, InstantiationException {
        Object obj=Class.forName(classname).newInstance();
        InvocationHandler handle = new AopHandler(obj);
        return Proxy.newProxyInstance(obj.getClass().getClassLoader(),obj.getClass().getInterfaces(),handle);
    }
    public static<T> T getBean(String classname,Class<T> clazz) throws IllegalAccessException, InstantiationException, ClassNotFoundException {
        return (T)getBean(classname);
    }
}

package cn.itcast.shujujiegou.StructuresAnalysis;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 * Created by likailong on 2016/9/29.
 */
public class BeanfatoryTest {
    public static void main(String [] args) throws IllegalAccessException, ClassNotFoundException, InstantiationException, NoSuchMethodException, InvocationTargetException {
        Hello aa = BeanFactory.getBean("cn.itcast.shujujiegou.StructuresAnalysis.HelloIml", HelloIml.class);
       aa.setInfo("hjaslg","sldkjgs");
        Method method = Hello.class.getDeclaredMethod("setInfo", String.class, String.class);
        method.invoke(new HelloIml(),"aaa","bbb");
    }
}

分析newinstance實際原理

從圖看出hello介面是代理指向因此代理物件與實現類無關用了位元組碼增強技術，故代理物件指向介面