Spring 使用配置文件+反射机制+工厂模式模拟IOC解耦（单例）案例

绝地灬酷狼 2023-02-11 15:30 118阅读 0赞

使用配置文件+反射机制+工厂模式模拟IOC解耦（单例）案例

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2d1YW5tYW80MzIy_size_16_color_FFFFFF_t_70][]

（1）客户端：

package com.njau.UI;
    
    import com.njau.Util.BeanFactory;
    import com.njau.service.AccountService;
    
    public class Client {
    
    
        public static void main(String[] args) {
    
            //AccountService accountService = new AccountServiceImpl();
    
            AccountService accountService = (AccountService)BeanFactory.getBean("accountService");
            accountService.saveData();
    
        }
    }

（2）service接口

package com.njau.service;
    
    public interface AccountService {
        //模拟保存数据
        void saveData();
    }

service接口实现类

package com.njau.service.serviceImpl;
    
    import com.njau.Util.BeanFactory;
    import com.njau.dao.AccountDao;
    import com.njau.dao.daoimpl.AccountDaoImpl;
    import com.njau.service.AccountService;
    
    public class AccountServiceImpl implements AccountService {
    
        //private AccountDao accountDao = new AccountDaoImpl();
    
        private AccountDao accountDao = (AccountDao)BeanFactory.getBean("accountDao");
        @Override
        public void saveData() {
            accountDao.saveData();
        }
    }

（3）dao接口

package com.njau.dao;
    
    public interface AccountDao {
        //模拟保存数据
        void saveData();
    }

dao接口实现类

package com.njau.dao.daoimpl;
    
    import com.njau.dao.AccountDao;
    
    public class AccountDaoImpl implements AccountDao {
        @Override
        public void saveData() {
            System.out.println("保存成功！！");
        }
    }

（4）配置文件解析（含反射机制与工厂模式）

package com.njau.Util;
    
    import java.io.IOException;
    import java.io.InputStream;
    import java.util.Enumeration;
    import java.util.HashMap;
    import java.util.Map;
    import java.util.Properties;
    
    public class BeanFactory {
        //定义一个Properties对象
        private static Properties properties;
    
        //定义一个Map，用于存放我们要创建的对象，我们把它称之为容器
        private static Map<String,Object> beans;
    
        //使用静态代码块为Properties对象赋值
        static {
            //实例化对象
            properties = new Properties();
            //获取properties对象的流对象
            InputStream inputStream = BeanFactory.class.getClassLoader().getResourceAsStream("bean.properties");
            try {
                properties.load(inputStream);
                //实例化容器
                beans = new HashMap<String, Object>();
                //取出配置文件中所有的key
                Enumeration<Object> keys = properties.keys();
                //遍历枚举
                while (keys.hasMoreElements()){
                    //从枚举中取出所有的key
                    String key = keys.nextElement().toString();
                    System.out.println(key);
                    //通过key，取出配置文件中对应的值，即全限定类名
                    String beanPath = properties.getProperty(key);
                    //通过全限定类名用反射的方式创建实例
                    Object instance = Class.forName(beanPath).newInstance();
                    //将key和实例存入map集合中，即存入beans中
                    beans.put(key,instance);
                }
            } catch (IOException e) {
                e.printStackTrace();
                //初始化异常
                throw new ExceptionInInitializerError("读取bean配置文件出错");
            } catch (Exception e) {
                e.printStackTrace();
                System.out.println("在遍历keys时，可能出现了异常");
            }
        }
    
        /**
         * 通过beanName获取对象（单例）
         * @param beanName
         * @return
         */
        public static Object getBean(String beanName){
            Object bean = beans.get(beanName);
            return bean;
        }
    
    }

（5）配置文件

accountService=com.njau.service.serviceImpl.AccountServiceImpl
    accountDao=com.njau.dao.daoimpl.AccountDaoImpl

参考：

[https://blog.csdn.net/weixin\_44268792/article/details/99207563][https_blog.csdn.net_weixin_44268792_article_details_99207563]

表示感谢！！

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[https_blog.csdn.net_weixin_44268792_article_details_99207563]: https://blog.csdn.net/weixin_44268792/article/details/99207563