jdk动态代理和cglib动态代理-蒲公英云

jdk动态代理和cglib动态代理

小灰灰 2022-07-28 01:09 372阅读 0赞

前言：动态代理作为代理模式的一种扩展形式，广泛应用于框架（尤其是基于AOP的框架）的设计与开发。

jdk动态代理

下面将代码实例展示

package cn.mode.proxy;
/** * 接口类 * @author zzh * */
public interface People { 
    void say(int i);
}
package cn.mode.proxy;
/** * 实现类 * @author zzh * */
public class Girl implements People { 
    @Override
    public void say(int i) {
        if (i == 1) {
            System.out.println("我在吃饭");
        } else {
            System.out.println("我什么事都没做");
        }
    }
}
package cn.mode.proxy;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.util.Date;
/** * 代理类 * @author zzh * */
public class SayHandler implements InvocationHandler { 
    private Object obj;
    //构造方法传入代理
    public SayHandler(Object obj) {
        this.obj = obj;
    }
    public SayHandler() {
    }
    @Override
    public Object invoke(Object proxy, Method method, Object[] args)
            throws Throwable {
        System.out.println("开始代理，时间：" + new Date());
        Object result = method.invoke(obj, args);
        System.out.println("代理结束");
        return result;
    }
}
package cn.mode.proxy;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Proxy;
/** * 测试类 * @author zzh * */
public class Test { 
    public static void main(String[] args) {
        People people = new Girl();
        //代理类
        InvocationHandler handler = new SayHandler(people);
        //代理对象
        People proxy = (People) Proxy.newProxyInstance(People.class.getClassLoader(), new Class[]{People.class}, handler);
        proxy.say(1);
    }
}

输出：
开始代理，时间：Sun Mar 27 21:24:58 CST 2016
我在吃饭
代理结束

jdk动态代理只能代理一个或多个接口，如果需要动态代理具体类或抽象类，可以使用cglib动态代理。

cglib动态代理

看一个例子

package cn.mode.proxy.cglib;
public class People {
    public void say() {
        System.out.println("吃吃");
    }
}
package cn.mode.proxy.cglib;
public class Girl extends People { 
    @Override
    public void say() {
        System.out.println("我在吃饭");
    }
}
package cn.mode.proxy.cglib;
import java.lang.reflect.Method;
import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;
public class PeopleProxy implements MethodInterceptor { 
    private Enhancer enhancer = new Enhancer();  
    public Object getProxy(Class<?> clazz){  
        //设置需要创建子类的类 
        enhancer.setSuperclass(clazz); 
        //回调
        enhancer.setCallback(this);  
        //通过字节码技术动态创建子类实例 
        return enhancer.create();  
    } 
    @Override
    public Object intercept(Object obj, Method method, Object[] args,
            MethodProxy proxy) throws Throwable {
        System.out.println("代理前");
        Object object = proxy.invokeSuper(obj, args);
        System.out.println("代理后");
        return object;
    }
}
package cn.mode.proxy.cglib;
public class Test {
    public static void main(String[] args) {
        PeopleProxy proxy = new PeopleProxy();
        People people = (People) proxy.getProxy(Girl.class);
        people.say();
    }
}