java动态代理+自定义注解，实现改变目标方法行为（不入侵方法本身）

package refactor; import net.sf.cglib.proxy.MethodProxy; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; public class DemoMethodInterceptor implements MyMethodInterceptor { public Object methodPreInvoke(Class<?> clazz, Method preMethod, Object... preMethodArgs) throws InvocationTargetException, IllegalAccessException { preMethod.setAccessible(true); return preMethod.invoke(MyMethodInterceptor.getProxy(clazz), preMethodArgs); } public Object methodPostInvoke(Class<?> clazz, Method postMethod, Object... postMethodArgs) throws InvocationTargetException, IllegalAccessException { postMethod.setAccessible(true); return postMethod.invoke(MyMethodInterceptor.getProxy(clazz), postMethodArgs); } @Override public Object intercept(Object o, Method method, Object[] args, MethodProxy methodProxy) throws Throwable { //o表示目标类，method目标类的方法，args目标类方法需要的形参，methodProxy表示代理类+目标方法。 //执行前置方法 if (method.isAnnotationPresent(MethodPreWrapper.class)) { MethodPreWrapper methodPreWrapper = method.getAnnotation(MethodPreWrapper.class); if (methodPreWrapper.argProviderClazz() == ArgNull.class) { methodPostInvoke(methodPreWrapper.clazz(), getMethod(methodPreWrapper.clazz(), methodPreWrapper.methodName())); } else if (!methodPreWrapper.argProviderMethodName().equals("")) { methodPreInvoke(methodPreWrapper.clazz(), getMethod(methodPreWrapper.clazz(), methodPreWrapper.methodName()), (Object[]) methodPreInvoke(methodPreWrapper.clazz(), getMethod(methodPreWrapper.argProviderClazz(), methodPreWrapper.argProviderMethodName()))); } } //执行目标类的方法。 Object result = methodProxy.invokeSuper(o, args); if (method.isAnnotationPresent(MethodPostWrapper.class)) { //执行后置方法 MethodPostWrapper methodPostWrapper = method.getAnnotation(MethodPostWrapper.class); if (methodPostWrapper.argProviderClazz() == ArgNull.class) { methodPostInvoke(methodPostWrapper.clazz(), getMethod(methodPostWrapper.clazz(), methodPostWrapper.methodName())); } else if (!methodPostWrapper.argProviderMethodName().equals("")) { methodPreInvoke(methodPostWrapper.clazz(), getMethod(methodPostWrapper.clazz(), methodPostWrapper.methodName()), (Object[]) methodPreInvoke(methodPostWrapper.clazz(), getMethod(methodPostWrapper.argProviderClazz(), methodPostWrapper.argProviderMethodName()))); } } return result; } private Method getMethod(Class<?> clazz, String methodName) throws NoSuchMethodException { Method[] methods = clazz.getDeclaredMethods(); for (Method method : methods) { if (method.getName().equals(methodName)) { return method; } } throw new NoSuchMethodException(String.format("java.lang.NoSuchMethodException: %s.%s", clazz.getName(), methodName)); } }