Proxy代理代码示例

jdk动态代理

/**
 * 代理类
 */
public interface IDao {
    String doThings(String metarita);
}

/**
 * 被代理类
 */
public class DaoImpl implements IDao {
    @Override
    public String doThings(String metarita) {
        System.out.println("原材料：" + metarita);
        System.out.println("我是A，我在doThings");
        return "成品";
    }
}

/**
 * 动态代理工厂
 */
public class ProxyFactory {

    private Object target;

    public ProxyFactory(Object target) {
        this.target = target;
    }

    public Object getProxyInstance() {
        return Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(),
                new InvocationHandler() {
                    @Override
                    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                        System.out.println("代理类干活前我先干的......");
                        Object invoke = method.invoke(target, args);
                        System.out.println("代理类干完活我先后的......");
                        return invoke;
                    }
                }
        );
    }
}

/**
 * 测试main
 */
class Test {
    public static void main(String[] args) {
        IDao target = new DaoImpl();
        // 输出目标对象信息
        System.out.println(target.getClass());
        IDao proxy = (IDao) new ProxyFactory(target).getProxyInstance();
        // 输出代理对象信息
        System.out.println(proxy.getClass());
        // 执行代理方法
        String things = proxy.doThings("000000000");
        System.out.println(things);
    }
}

cglib动态代理

<dependency>
    <groupId>cglib</groupId>
    <artifactId>cglib</artifactId>
    <version>3.2.5</version>
</dependency>

/**
 * 被代理类
 */
public class Dao {

    public String doThings(String metarita) {
        System.out.println("原材料：" + metarita);
        System.out.println("我是A，我在doThings");
        return "成品";
    }
}


import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;

import java.lang.reflect.Method;

/**
 * 代理工厂
 */
public class ProxyFactory implements MethodInterceptor {

    private Object target;

    public ProxyFactory(Object target) {
        this.target = target;
    }

    /**
     * 生成代理类
     * @return
     */
    public Object getProxyInstance() {
        Enhancer enhancer = new Enhancer();
        enhancer.setSuperclass(target.getClass());
        enhancer.setCallback(this);
        return enhancer.create();
    }

    @Override
    public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {

        System.out.println("干活前");
        // 注意不能使用o,会死循环
        Object invoke = method.invoke(this.target, objects);
        System.out.println("干活后");

        return invoke;
    }
}

/**
 * 测试main
 */
class Test {
    public static void main(String[] args) {
        //目标对象
        Dao target = new Dao();
        System.out.println(target.getClass());
        //代理对象
        Dao proxy = (Dao) new ProxyFactory(target).getProxyInstance();
        System.out.println(proxy.getClass());
        //执行代理对象方法
        String things = proxy.doThings("0000000");
        System.out.println(things);
    }
}

• jdk动态代理对象必须实现接口
• cglib使用字节码处理框架ASM，通过生成被代理对象的子类方式实现
• cglib无法代理final类