手动创建代理实现AOP功能

我们在很多时候，并不能直接使用spring aop功能，需要自己实现代理对java代码进行aop操作。这里使用手动代理的方式对AOP进行处理。

一、定义一个注解用于需要特殊处理的方法

@documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface StepAnnotation {
    String name();
}

二、定义一个BeanPostProcessor 用于对需要特殊处理方法用代理代替原有类

@Configuration
public class StepBeanPostProcessor  implements BeanPostProcessor {
    @Override
    public Object postProcessBeforeInitialization(Object o, String beanName) throws BeansException {
        try {
            Method[] methods = o.getClass().getMethods();
            for (Method method : methods) {
                StepAnnotation annotation = method.getAnnotation(StepAnnotation.class);
                if (annotation != null) {
                    Object o1 = PluginStepProxyFactory.getInstance(o.getClass());
                    Field[] allFields = FieldUtils.getAllFields(o.getClass());
                    for (Field field : allFields) {
                        if (field.getDeclaredAnnotations().length == 0) {
                            continue;
                        }
                        field.setAccessible(true);
                        field.set(o1, field.get(o));
                    }
                    return o1;
                }
            }
        } catch (IllegalAccessException e) {
            CommonLogUtil.error("StepBeanPostProcessor.postProcessBeforeInitialization fail", e);
        }

        return o;
    }

    @Override
    public Object postProcessAfterInitialization(Object o, String beanName) throws BeansException {
        return o;
    }
}

三、具体创建代理实现类

public class PluginStepProxyFactory {

    
    public static  T getInstance(Class clazz) {
        Enhancer enhancer = new Enhancer();
        enhancer.setSuperclass(clazz);
        enhancer.setCallback((MethodInterceptor)(o,method,objects,methodProxy)->{
            StepAnnotation stepAnnotation = method.getAnnotation(StepAnnotation.class);
            if (stepAnnotation != null) {
                TimeInterval timer = DateUtil.timer();
                Object res = methodProxy.invokeSuper(o, objects);
                long interval = timer.intervalMs();
                CommonLogUtil.info("step " + stepAnnotation.name() + "time 消耗" + interval + "ms,result is:" + res);
                return res;
            }
            return methodProxy.invokeSuper(o, objects);
        });
        return (T) enhancer.create();
    }
}

四、使用test类进行测试

 public List getData(){
        LambdaQueryWrapper queryWrapper = new LambdaQueryWrapper<>();
        testStep();
       return testService.list(queryWrapper);
    }

    @StepAnnotation(name = "测试步骤")
    public String testStep() {
        try {
            CommonLogUtil.info("调用步骤111");
            Thread.sleep(1500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return "step--";

    }