<dependencies>
    <!--導入spring的坐標spring-context，對應版本是5.2.10.RELEASE-->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>5.2.10.RELEASE</version>
    </dependency>
</dependencies>

public interface BookDao {
    public void save();
}

public class BookDaoImpl implements BookDao {
    public void save() {
        System.out.println("book dao save ...");
    }
}

public interface BookService {
    public void save();
}

public class BookServiceImpl implements BookService {
    private BookDao bookDao = new BookDaoImpl();
    public void save() {
        System.out.println("book service save ...");
        bookDao.save();
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<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">
 
    <!--
		bean標簽：表示配置bean
    	id屬性：表示給bean起名字
    	class屬性：表示給bean定義類型
	-->
    <bean id="bookService" class="com.itheima.service.impl.BookServiceImpl"></bean>

</beans>

public class App {
    public static void main(String[] args) {
        //1.創(chuàng)建IoC容器對象，加載spring核心配置文件
        ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        //2 從IOC容器中獲取Bean對象(BookService對象)
        BookService bookService= (BookService)ctx.getBean("bookService");
        //3 調(diào)用Bean對象(BookService對象)的方法
        bookService.save();
    }
}

public class BookServiceImpl implements BookService {
    private BookDao bookDao;  //【第一步】刪除使用new的形式創(chuàng)建對象的代碼
    public void save() {
        System.out.println("book service save ...");
        bookDao.save();
    }
}

public class BookServiceImpl implements BookService {
    private BookDao bookDao;
    public void save() {
        System.out.println("book service save ...");
        bookDao.save();
    }
    //【第二步】提供依賴對象對應的setter方法
    public void setBookDao(BookDao bookDao) {
        this.bookDao = bookDao;
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<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">
    <!--
		bean標簽：表示配置bean
    	id屬性：表示給bean起名字
    	class屬性：表示給bean定義類型
	-->
    <bean id="bookDao" class="com.itheima.dao.impl.BookDaoImpl"/>

    <bean id="bookService" class="com.itheima.service.impl.BookServiceImpl">
        <!--配置server與dao的關系
			property標簽：表示配置當前bean的屬性
        	name屬性：表示配置哪一個具體的屬性
        	ref屬性：表示參照哪一個bean
		-->
        <property name="bookDao" ref="bookDao"/>
    </bean>
</beans>