Spring中的工厂类

目录

1.ApplicationContext

4.2.BeanFactory

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1.ApplicationContext

ApplicationContext的实现类，如下图：

• ClassPathXmlApplicationContext：加载类路径下 Spring 的配置文件

• FileSystemXmlApplicationContext：加载本地磁盘下 Spring 的配置文件

4.2.BeanFactory

• spring中工厂的类结构图

配置文件pom.xml：

<dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>5.1.8.RELEASE</version></dependency><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-log4j12</artifactId><version>1.7.30</version></dependency></dependencies>

• 区别：

  • ApplicationContext：只要一读取配置文件，默认情况下就会创建对象。

/*** 业务层实现类*/
public class UserServiceImpl implements UserService {private UserDao userDao;public UserServiceImpl() {System.out.println("UserServiceImpl对象创建了...");}public UserServiceImpl(UserDaoImpl userDao) {this.userDao = userDao;}public void addUser(){userDao.addUser();}
}

/*** 模拟表现层*/
public class Client {public static void main(String[] args) {new ClassPathXmlApplicationContext("applicationContext.xml");System.out.println("Spring IOC容器创建好了");}
}

BeanFactory：是在 getBean 的时候才会创建对象。

/*** 业务层实现类*/
public class UserServiceImpl implements UserService {private UserDao userDao;public UserServiceImpl() {System.out.println("UserServiceImpl对象创建了...");}public void setUserDao(UserDao userDao) {this.userDao = userDao;}public void addUser(){userDao.addUser();}
}

 /*** 模拟表现层*/public class Client {public static void main(String[] args) {new XmlBeanFactory(new ClassPathResource("applicationContext.xml"));System.out.println("Spring IOC容器创建好了");}}