spring自定义bean工厂模式解耦

在resources下创建bean.properties

accountService=cn.flypig666.service.impl.AccountServiceImpl
accountDao=cn.flypig666.dao.impl.AccountDaoImpl

创建工厂：BeanFactory.java

创建单例对象效果更好

创建Map<String,Object>类型的容器beans

 1 //定义一个Properties对象
 2     private static Properties props;
 3 
 4     //定义一个Map，用于存放我们要创建的对象，称之为容器
 5     private static Map<String,Object> beans;
 6 
 7     //使用静态代码块为Properties对象赋值
 8     static {
 9         try {
10             //实例化对象
11             props = new Properties();
12             //获取properties文件的流对象,创建在resources文件夹下的properties文件会成为类根路径下的文件，不用写包名
13             InputStream in = BeanFactory.class.getClassLoader().getResourceAsStream("bean.properties");
14             props.load(in);
15             //实例化容器
16             beans = new HashMap<String, Object>();
17             //取出配置文件中所有的 Key
18             Enumeration  keys = props.keys();
19             //遍历枚举
20             while (keys.hasMoreElements()){
21                 //取出每个key
22                 String key = keys.nextElement().toString();
23                 //根据key获取value
24                 String beanPath = props.getProperty(key);
25                 //反射创建对象
26                 Object value = Class.forName(beanPath).newInstance();
27                 //把key和value存入容器中
28                 beans.put(key,value);
29             }
30         } catch (Exception e) {
31             throw new ExceptionInInitializerError("初始化properties失败");
32         }
33     }
34 
35     public static Object getBean(String beanName){
36         return beans.get(beanName);
37     }

 1     /**
 2      * 根据Bean的名称获取bean对象
 3      * @param beanName
 4      * @return
 5      */
 6     public static Object getBean(String beanName){
 7         Object bean = null;
 8         try{
 9             String beanPath = props.getProperty(beanName);
10             System.out.println(beanPath);
11             bean = Class.forName(beanPath).newInstance();
12         }catch (Exception e){
13             e.printStackTrace();
14         }
15         return bean;
16     }
17 
18 }

通过反射获取对象

/**
 * 账户业务层实现类
 */
public class AccountServiceImpl implements IAccountService {

    //private IAccountDao accountDao = new AccountDaoImpl();
    private IAccountDao accountDao = (IAccountDao) BeanFactory.getBean("accountDao");

    public void saveAccount(){
        accountDao.saveAccount();
    }
}

/**
 * 模拟一个表现层，用于调用业务层
 */
public class Client {

    public static void main(String[] args) {
//        IAccountService accountService = new AccountServiceImpl();
        IAccountService accountService = (IAccountService) BeanFactory.getBean("accountService");
        accountService.saveAccount();
    }
}