Spring组件开发模式支持SPEL表达式

import org.springframework.aop.support.AopUtils;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.*;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.expression.StandardBeanExpressionResolver;
import org.springframework.core.annotation.AnnotationUtils;
import java.lang.reflect.Method;
/**
 * 针对 Spring 实现某些特殊逻辑时，支持 SPEL 表达式
 * @author liuzh
 */
public class SpelUtil implements ApplicationContextAware {
  /**
   * 通过 ApplicationContext 处理时
   * @param applicationContext
   * @throws BeansException
   */
  @Override
  public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
    if (applicationContext instanceof ConfigurableApplicationContext) {
      ConfigurableApplicationContext context = (ConfigurableApplicationContext)applicationContext;
      ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
      StandardBeanExpressionResolver expressionResolver = new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader());
      for (String definitionName : applicationContext.getBeanDefinitionNames()) {
        BeanDefinition definition = beanFactory.getBeanDefinition(definitionName);
        Scope scope = (definition != null ? beanFactory.getRegisteredScope(definition.getScope()) : null);
        //根据自己逻辑处理
        //例如获取 bean
        Object bean = applicationContext.getBean(definitionName);
        //获取实际类型
        Class<?> targetClass = AopUtils.getTargetClass(bean);
        //获取所有方法
        for (Method method : targetClass.getDeclaredMethods()) {
          //获取自定义的注解(Bean是个例子）
          Bean annotation = AnnotationUtils.findAnnotation(method, Bean.class);
          //假设下面的 value 支持 SPEL
          for (String val : annotation.value()) {
            //解析 ${} 方式的值
            val = beanFactory.resolveEmbeddedValue(val);
            //解析 SPEL 表达式
            Object value = expressionResolver.evaluate(val, new BeanExpressionContext(beanFactory, scope));
            //TODO 其他逻辑
          }
        }
      }
    }
  }
}

import org.springframework.aop.support.AopUtils;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.config.*;
import org.springframework.context.annotation.Bean;
import org.springframework.context.expression.StandardBeanExpressionResolver;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.util.ReflectionUtils;
/**
 * 针对 Spring 实现某些特殊逻辑时，支持 SPEL 表达式
 * @author liuzh
 */
public class SpelUtil2 implements BeanPostProcessor, BeanFactoryAware, BeanClassLoaderAware {
  private BeanFactory beanFactory;
  private BeanExpressionResolver resolver;
  private BeanExpressionContext expressionContext;
  /**
   * 解析 SPEL
   * @param value
   * @return
   */
  private Object resolveExpression(String value){
    String resolvedValue = resolve(value);
    if (!(resolvedValue.startsWith("#{") && value.endsWith("}"))) {
      return resolvedValue;
    }
    return this.resolver.evaluate(resolvedValue, this.expressionContext);
  }
  /**
   * 解析 ${}
   * @param value
   * @return
   */
  private String resolve(String value){
    if (this.beanFactory != null && this.beanFactory instanceof ConfigurableBeanFactory) {
      return ((ConfigurableBeanFactory) this.beanFactory).resolveEmbeddedValue(value);
    }
    return value;
  }
  @Override
  public void setBeanClassLoader(ClassLoader classLoader) {
    this.resolver = new StandardBeanExpressionResolver(classLoader);
  }
  @Override
  public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
    this.beanFactory = beanFactory;
    if(beanFactory instanceof ConfigurableListableBeanFactory){
      this.resolver = ((ConfigurableListableBeanFactory) beanFactory).getBeanExpressionResolver();
      this.expressionContext = new BeanExpressionContext((ConfigurableListableBeanFactory) beanFactory, null);
    }
  }
  @Override
  public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
    return bean;
  }
  /**
   * 对 bean 的后置处理
   * @param bean
   * @param beanName
   * @return
   * @throws BeansException
   */
  @Override
  public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
    //获取实际类型
    Class<?> targetClass = AopUtils.getTargetClass(bean);
    //获取所有方法
    ReflectionUtils.doWithMethods(targetClass, method -> {
      //获取自定义的注解(Bean是个例子）
      Bean annotation = AnnotationUtils.findAnnotation(method, Bean.class);
      //假设下面的 value 支持 SPEL
      for (String val : annotation.value()) {
        //解析表达式
        Object value = resolveExpression(val);
        //TODO 其他逻辑
      }
    }, method -> {
      //TODO 过滤方法
      return true;
    });
    return null;
  }
}