动态代理 | Brust’Blog

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Mar 11, 2023

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Java 动态代理一般分为 JDK 动态代理和 CGLIB 动态代理，二者的区别如下：

JDK 动态代理是基于接口的代理，只能代理实现了接口的类，而 CGLIB 动态代理是基于继承的代理，可以代理未实现接口的类。

JDK 动态代理生成的代理对象性能较低，因为每次生成代理对象时都需要通过反射来进行，而 CGLIB 动态代理在生成代理对象时会使用代码生成技术，性能更高。

以下是 JDK 动态代理和 CGLIB 动态代理的代码实现：

JDK 动态代理：


public interface Subject {
    void request();
}

public class RealSubject implements Subject {
    @Override
    public void request() {
        System.out.println("RealSubject is running...");
    }
}

public class JDKProxyHandler implements InvocationHandler {
    private Object target;

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

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("JDKProxyHandler is running...");
        Object result = method.invoke(target, args);
        return result;
    }
}

public class ProxyTest {
    public static void main(String[] args) {
        RealSubject realSubject = new RealSubject();
        Subject proxySubject = (Subject) Proxy.newProxyInstance(
                realSubject.getClass().getClassLoader(),
                realSubject.getClass().getInterfaces(),
                new JDKProxyHandler(realSubject)
        );
        proxySubject.request();
    }
}

CGLIB 动态代理：


public class RealSubject {
    public void request() {
        System.out.println("RealSubject is running...");
    }
}

public class CGLIBProxyHandler implements MethodInterceptor {
    @Override
    public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
        System.out.println("CGLIBProxyHandler is running...");
        Object result = methodProxy.invokeSuper(o, objects);
        return result;
    }
}

public class ProxyTest {
    public static void main(String[] args) {
        Enhancer enhancer = new Enhancer();
        enhancer.setSuperclass(RealSubject.class);
        enhancer.setCallback(new CGLIBProxyHandler());
        RealSubject proxySubject = (RealSubject) enhancer.create();
        proxySubject.request();
    }
}