反射注入失败问题解决

淡淡的烟草味﹌ 2021-07-24 17:34 513阅读 0赞

# 一 问题提出 #

当使用反射机制，会使得类中注入对象为空，注入失效。

# 二 解决方式 #

使用Spring的ApplicationContext可以解决注入失败问题。

# 三 代码 #

1 工具类

/**
    * Copyright (C), 2020-2020, 软件公司
    * FileName: ApplicationContextHelper.java
    * Author:   cakin
    * Date:     2020/8/5
    * Description: 获取环境中的bean
    */
    package com.project.common.util;
    
    
    import org.springframework.beans.BeansException;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.ApplicationContextAware;
    import org.springframework.stereotype.Service;
    
    
    /**
    * @className: ApplicationContextHelper
    * @description: 获取环境中的bean
    * @date: 2020/8/5
    * @author: cakin
    */
    @Service
    public class ApplicationContextHelper implements ApplicationContextAware {
    
    
        /**
         * 应用上下文
         */
        private static ApplicationContext applicationContext;
    
    
        @Override
        public void setApplicationContext(ApplicationContext context) throws BeansException {
    
    
            applicationContext = context;
        }
    
    
        /**
         * 获取bean
         *
         * @param clazz bean所属的类
         * @return T 返回的bean
         */
        public static <T> T popBean(Class<T> clazz) {
            //先判断是否为空
            if (applicationContext == null) {
                return null;
            }
            return applicationContext.getBean(clazz);
        }
    
    
        /**
         * 获取bean
         *
         * @param clazz bean所属的类
         * @param name bean的name
         * @return T 返回的bean
         */
        public static <T> T popBean(String name, Class<T> clazz) {
            if (applicationContext == null) {
                return null;
            }
            return applicationContext.getBean(name, clazz);
        }
    }

2 PersonInvoiceServiceImpl类

/**
    * Copyright (C), 2020-2020, 软件公司
    * FileName: PersonInvoiceServiceImpl.java
    * Author:   cakin
    * Date:     2020/7/24
    * Description: 实现类
    */
    //  如果使用反射，PersonInvoiceServiceImpl注入personInvoiceDao会失败
    @Service
    public class PersonInvoiceServiceImpl extends BaseServiceImpl<PersonInvoice> implements PersonInvoiceService {
    
    
        Logger logger = LogManager.getLogger(this.getClass());
    
    
        @Autowired
        private PersonInvoiceDao personInvoiceDao; // 通过反射机制，这里是无法注入成功的，因为反射是动态生成的，在系统初始化时，没法完成注入
    
        public boolean updatePersonInvoice(PersonInvoice personInvoice) {
        PersonInvoice oldPersonInvoice = personInvoiceDao.findOne(personInvoice.getId());
        if (oldPersonInvoice != null) {
            try {
                MyBeanUtils.copyBeanNotNull2Bean(personInvoice, oldPersonInvoice);
            } catch (Exception e) {
                e.printStackTrace();
            }
            oldPersonInvoice.setUpdateTime(new Date());
            personInvoiceDao.saveAndFlush(oldPersonInvoice);
            logger.debug(oldPersonInvoice.toString());
            return true;
        } else {
            logger.error("data doesn't exist:" + personInvoice.toString());
            return false;
        }
    }

3 调用点

Class className = Class.forName(CLASSNAME);
    personInvoiceService = (PersonInvoiceServiceImpl) ApplicationContextHelper.popBean("com.project.service.impl.PersonInvoiceServiceImpl"); // 获得系统初始化时注入的bean
    personInvoiceService.updatePersonInvoice(personInvoice); // 这样就可以调用PersonInvoiceServiceImpl中的方法updatePersonInvoice，因为方法中的personInvoiceDao在系统初始化时就已经注入了，不会出现无法注入问题