How to get method arguments using reflection

Question

This method is first checked by beanDefintirions for the original Beans (Configureablelistablebeanfactory beanFactory is used; ).

ConfigurableListableBeanFactory beanFactory; injected.

Then all the methods of the original bean, which was obtained from the BeanFactory, are iterated over. After searching over the methods of a certain annotation, we get the Bean from the Applicationcontext.

This Bean is a proxy wrapper over the original Bean, which was formed at the - > postProcessBeforeInitialization() stage. Now through this bean, I call a method that has been marked with the annotation I need, but it requires another argument Obj ..args.

How do I get the missing argument ?

Использую Srping 5.x, java 11

private void runMethodWithPostProxyThirdPhaseAnnotation(String beanName, ApplicationContext applicationContext) {

      BeanDefinition beanDefinition = beanFactory.getBeanDefinition(beanName);


      try {
          String originalBeanClassName = beanDefinition.getBeanClassName();

          if (originalBeanClassName != null) {
              Class<?> originalClass = Class.forName(originalBeanClassName);
              Method[] methods = originalClass.getMethods();

              for (Method method : methods) {
                  if (method.isAnnotationPresent(PostProxyThirdPhase.class)) {
                      

                      String originalMethodName = method.getName();
                      Class<?>[] parameterTypesFromOriginalMethod = method.getParameterTypes();

                      Object beanAfterProxy = applicationContext.getBean(beanName);

                      Method methodFromProxyBean = beanAfterProxy
                              .getClass()
                              .getMethod(originalMethodName, parameterTypesFromOriginalMethod);

                      methodFromProxyBean.invoke(beanAfterProxy, ?);
                  }
              }
          }

      } catch (ClassNotFoundException | NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
          e.printStackTrace();
      }

}

skyho · Accepted Answer · 2021-12-27 18:02:31Z

Solution

three-phase constructor (implementation).

The answer was in the documentation for the method :

public Object invoke(Object obj, Object... args)

@param args the arguments used for the method call


import bean.post.process.annotation.PostProxyThirdPhase;
import bean.post.process.bean.Quoter;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationListener;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.stereotype.Component;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;

@Component
public class PostProxyInvokerContextListener implements ApplicationListener<ContextRefreshedEvent> {

    private final ConfigurableListableBeanFactory beanFactory;

    private final Quoter quoter;

    public PostProxyInvokerContextListener(ConfigurableListableBeanFactory beanFactory, Quoter quoter) {
        this.beanFactory = beanFactory;
        this.quoter = quoter;
    }


    @Override
    public void onApplicationEvent(ContextRefreshedEvent event) {
        ApplicationContext applicationContext = event.getApplicationContext();

        String[] beanDefinitionNames = applicationContext.getBeanDefinitionNames();

        Arrays.stream(beanDefinitionNames)
                .forEach(beanName -> runMethodWithPostProxyThirdPhaseAnnotation(beanName, applicationContext));
    }


    private void runMethodWithPostProxyThirdPhaseAnnotation(String beanName, ApplicationContext applicationContext) {

        BeanDefinition beanDefinition = beanFactory.getBeanDefinition(beanName);

        try {
            String originalBeanClassName = beanDefinition.getBeanClassName();

            if (originalBeanClassName != null) {
                Class<?> originalClass = Class.forName(originalBeanClassName);
                Method[] methods = originalClass.getMethods();

                for (Method method : methods) {
                    if (method.isAnnotationPresent(PostProxyThirdPhase.class)) {

                        String originalMethodName = method.getName();
                        Class<?>[] parameterTypesFromOriginalMethod = method.getParameterTypes();

                        Object beanAfterProxy = applicationContext.getBean(beanName);

                        Method methodFromProxyBean = beanAfterProxy
                                .getClass()
                                .getMethod(originalMethodName, parameterTypesFromOriginalMethod);

                        Object[] args = new Object[]{quoter};

                        methodFromProxyBean.invoke(beanAfterProxy, args);
                    }
                }
            }

        } catch (ClassNotFoundException | NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
            e.printStackTrace();
        }

    }
}

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