Spring

1. 入门案例：DI

class BookServiceImpl{ //之前开发：接口 = 实现类 （service和dao耦合） //private BookDao bookDao = new BookDaoImpl(); //spring之后 （解耦：service实现类使用dao接口，不知道具体的实现类） private BookDao bookDao; setter方法 } 模拟spring执行过程 创建service实例：BookService bookService = new BookServiceImpl() -->IoC <bean> 创建dao实例：BookDao bookDao = new BookDaoImple() -->IoC 将dao设置给service：bookService.setBookDao(bookDao); -->DI <property>

1.1 目标类

创建BookService接口和实现类 创建BookDao接口和实现类 将dao和service配置 xml文件 使用api测试

1.2 dao

public interface BookDao { public void save(); } public class BookDaoImpl implements BookDao { @Override public void save() { System.out.println("di add book"); } }

1.3service

public interface BookService { public abstract void addBook(); } public class BookServiceImpl implements BookService { // 方式1：之前，接口=实现类 // private BookDao bookDao = new BookDaoImpl(); // 方式2：接口 + setter private BookDao bookDao; public void setBookDao(BookDao bookDao) { this.bookDao = bookDao; } @Override public void addBook(){ this.bookDao.save(); } }

1.4 配置文件

<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <!-- 模拟spring执行过程 创建service实例：BookService bookService = new BookServiceImpl() IoC <bean> 创建dao实例：BookDao bookDao = new BookDaoImpl() IoC 将dao设置给service：bookService.setBookDao(bookDao); DI <property> <property> 用于进行属性注入 name： bean的属性名，通过setter方法获得 setBookDao ##> BookDao ##> bookDao ref ：另一个bean的id值的引用 --> <!-- 创建service --> <bean id="bookServiceId" class="com.itheima.b_di.BookServiceImpl"> <property name="bookDao" ref="bookDaoId"></property> </bean> <!-- 创建dao实例 --> <bean id="bookDaoId" class="com.itheima.b_di.BookDaoImpl"></bean> </beans>

1.5测试

@Test public void demo01(){ //从spring容器获得 String xmlPath = "com/itheima/b_di/beans.xml"; ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath); BookService bookService = (BookService) applicationContext.getBean("bookServiceId"); bookService.addBook(); }