public interface UserDao {    void save();}public class UserDaoImpl implements UserDao {    private String name;        public void save() {        System.out.println("save() is called, name: "+name);    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    }

package com.maple.util;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;import com.maple.dao.UserDao;import com.maple.dao.impl.UserDaoImpl;public class ProxyFactory implements InvocationHandler {    private Object target;        public Object createUserDao(Object target){        this.target=target;        return Proxy.newProxyInstance(this.target.getClass().getClassLoader(),                        this.target.getClass().getInterfaces(), this);    }    @Override    public Object invoke(Object proxy, Method method, Object[] args)            throws Throwable {        System.out.println(proxy.getClass().getName());        Object result=null;        UserDaoImpl userDao=(UserDaoImpl)this.target;        if(userDao.getName()!=null){            result=method.invoke(userDao, args);        }else{            System.out.println("the name is null");        }        return result;    }}

@Test    public void test() {        ProxyFactory pf=new ProxyFactory();        UserDaoImpl u=new UserDaoImpl();        u.setName("maple");        UserDao userDao=(UserDao) pf.createUserDao(u);        userDao.save();    }

package com.maple.dao.impl;public class UserDaoImpl2{    private String name;        public void save() throws InterruptedException {        Thread.sleep(3000);        System.out.println("save() is called, name: "+name);    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public void raiseException(){        throw new RuntimeException("this is test");    }    }

package com.maple.util;import java.lang.reflect.Method;import com.maple.dao.impl.UserDaoImpl2;import net.sf.cglib.proxy.Enhancer;import net.sf.cglib.proxy.MethodInterceptor;import net.sf.cglib.proxy.MethodProxy;public class CglibFactory implements MethodInterceptor {    private Object target;    public Object createUserDao(Object target){        this.target=target;        Enhancer enhancer=new Enhancer();        enhancer.setSuperclass(target.getClass());        enhancer.setCallback(this);        return enhancer.create();    }        @Override    public Object intercept(Object proxy, Method method, Object[] args,            MethodProxy methodProxy) throws Throwable {        UserDaoImpl2 userDao=(UserDaoImpl2)target;        System.out.println("begin");        if(userDao.getName()!=null){            method.invoke(target, args);        }else{            System.out.println("the name is null");        }        System.out.println("end");        return null;    }}

@Test    public void test2() throws InterruptedException{        CglibFactory cf=new CglibFactory();        UserDaoImpl2 temp=new UserDaoImpl2();        UserDaoImpl2 userDao=(UserDaoImpl2)cf.createUserDao(temp);        userDao.save();        temp.setName("aa");        userDao=(UserDaoImpl2)cf.createUserDao(temp);        userDao.save();    }