Spring 使用配置文件+反射机制+工厂模式模拟IOC解耦（单例）案例

使用配置文件+反射机制+工厂模式模拟IOC解耦（单例）案例

（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

表示感谢！！