一、自动装配

1.1、BookDao接口和实现类

java 复制代码

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

1.2、BookService接口和实现类

java 复制代码

public interface BookService {
    void save();
}
public class BookServiceImpl implements BookService {
    private BookDao bookDao;
    public void setBookDao(BookDao bookDao) {
        this.bookDao = bookDao;
    }
    public void save(){
        bookDao.save();
    }
}

1.3、配置文件

XML 复制代码

<?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 id="bookDao" class="com.itheima.dao.impl.BookDaoImpl" ></bean>
    <bean id="bookService" name="service" class="com.itheima.service.impl.BookServiceImpl" autowire="byType"></bean>
</beans>

1.4、使用方法

java 复制代码

public static void main(String[] args) {
        ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        BookService bookService = (BookService) ctx.getBean("service");
        bookService.save();
    }

1.5、总结

在配置文件中添加autowire属性为byType
spring会按照BookDao类型找到对应的Bean实现注入