第一章 Spring的基本应用.html

配置文件ApplicationContext.xml要放在src下，其作用是：将指定的类配置给Spring，让Spring创建其对象的实例。

ApplicationContext.xml

<?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">
        <!-- 将指定的类配置给Spring，让Spring创建其对象的实例 -->
        <bean id="userDao" class="com.yang.ioc.UserDaoImpl"></bean>
        <bean id="userService" class="com.yang.ioc.UserServiceImpl">
        <!-- propert用于调用bean实例中的setUserDao()完成属性赋值，从而实现依赖注入 -->
        <property name="userDao" ref="userDao"></property>
        </bean>
</beans>

样例一： 

UserDao.java

public interface UserDao {
    public void say();
}

UserDaoImpl .java

public class UserDaoImpl implements UserDao {

    public void say() {    
        System.out.println("Hello");
    }
}

TestIoc.java

public class TestIoc {
    /**
     * 测试类
     */
    public static void main(String[] args) {
        //1.初始化spring容器，加载配置文件
         ApplicationContext applicationContext=new ClassPathXmlApplicationContext("ApplicationContext.xml");
         //2.通过容器获取userDao实例
         UserDao userDao= (UserDao) applicationContext.getBean("userDao");
         //3.通过实例中的say()方法
         userDao.say();
    }
}

样例二： 

UserService.java

public interface UserService {
    public void say();
}

UserServiceImpl.java

public class UserServiceImpl implements UserService{
    //声明UserDao属性
    private UserDao userDao;
    //添加UserDao属性的setter方法，用于实现依赖注入
    public void setUserDao(UserDao userDao){
        this.userDao=userDao;
    }
    //实现接口中的方法
    public void say(){
        this.userDao.say();
        System.out.println("UserService hello");
    }
}

TestDi.java

public class TestDi {
    /**
     * 测试类
     */
    public static void main(String[] args) {
    //1.初始化spring容器，加载配置文件
     ApplicationContext applicationContext=new ClassPathXmlApplicationContext("ApplicationContext.xml");
     //2.通过容器获取UserService实例
     UserService userService= (UserService) applicationContext.getBean("userService");
     //3.通过实例中的say()方法
     userService.say();
    }
}