自己写的一个 CGBLIB 动态代理【原创】

CGLIB代理类，用CGLIB来实现一个代理类。大致原理描述如下：

1、使用Enhancer类来生成一个继续于被代理类的子类，此子类会重写被代理类（父类）中所有的非final的public方法；

2、当调用代理类的某个方法时实际上通过一个MethodInterceptor委托来间接调用的；

3、MethodInterceptor的intercept方法会对被代理类的方法进行增强（增强的逻辑是通过Interceptor接口来实现的）并调用被代理类（super class）的相关方法。

调用过程如下图：

CglibProxy类实现核心代理逻辑，并提供一个Interceptor接口供客户端来实现增强逻辑。

package proxy;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import lombok.AccessLevel;

import lombok.RequiredArgsConstructor;

import net.sf.cglib.proxy.Enhancer;

import net.sf.cglib.proxy.MethodInterceptor;

import net.sf.cglib.proxy.MethodProxy;

/**

 * @author xfyou

 */

@RequiredArgsConstructor(access = AccessLevel.PRIVATE)

public class CglibProxy<T> {

  private final Class<T> targetClass;

  private final MethodInterceptor methodInterceptor;

  public static <T> CglibProxy<T> newInstance(Class<T> targetClass, Interceptor interceptor) {

    return new CglibProxy<>(targetClass, new MethodInterceptor() {

      @Override

      public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {

        interceptor.before(obj);

        Object invokeResult;

        try {

          invokeResult = proxy.invokeSuper(obj, args);

        } catch (Throwable e) {

          interceptor.exception(obj, e);

          throw new InvocationTargetException(e);

        }

        interceptor.after(obj);

        return invokeResult;

      }

    });

  }

  @SuppressWarnings("unchecked")

  public T createNewObj() {

    return (T) createNewEnhancer().create();

  }

  private Enhancer createNewEnhancer() {

    Enhancer enhancer = new Enhancer();

    enhancer.setSuperclass(targetClass);

    enhancer.setCallback(methodInterceptor);

    return enhancer;

  }

  public interface Interceptor {

    /**

     * Do something before invoke the super class method

     *

     * @param obj Instances of proxied objects

     */

    void before(Object obj);

    /**

     * Do something after invoked the super class method

     *

     * @param obj Instances of proxied objects

     */

    void after(Object obj);

    /**

     * Do something when exception occurred when invoke the super class method

     *

     * @param obj Instances of proxied objects

     * @param e Exception

     */

    void exception(Object obj, Throwable e);

  }

}

WorkProxy类用来对Work类进行代理，生成的是一个单例的代理类。

package proxy;

import proxy.CglibProxy.Interceptor;

/**

 * @author xfyou

 * @date 2019/10/15

 */

public class WorkProxy {

  private static Work proxyObject;

  private static Interceptor interceptor = new Interceptor() {

    @Override

    public void before(Object obj) {

      System.out.println("before");

    }

    @Override

    public void after(Object obj) {

      System.out.println("after");

    }

    @Override

    public void exception(Object obj, Throwable e) {

      System.out.println("exception");

    }

  };

  static {

    proxyObject = CglibProxy.newInstance(Work.class, interceptor).createNewObj();

  }

  public static Work get() {

    return proxyObject;

  }

}

被代理的Work类如下：

package proxy;

/**

 * Work

 */

public class Work {

    public void doWork() {

        System.out.println("Do work");

    }

}

测试代码：

package proxy;

/**

 * @author xfyou

 * @date 2019/10/15

 */

public class Test {

  public static void main(String[] args) {

    WorkProxy.get().doWork();

  }

}

巴特西

自己写的一个 CGBLIB 动态代理【原创】

最新文章

热门文章