Spring6-基于XML自动装配

news2025/6/9 23:02:22

一、介绍

自动装配：
根据指定的策略，在IOC容器中匹配某一个bean，自动为指定的bean中所依赖的类类型或接口类型属性赋值

二、创建controller

package com.wsy.auto.controller;

import com.wsy.auto.service.UserService;
import com.wsy.auto.service.UserServiceImpl;
import org.springframework.beans.factory.annotation.Autowired;

/**
 * @author within
 * @date 2023-02-09 11:01
 */
public class UserController {


    private UserService userService;

    public void setUserService(UserService userService) {
        this.userService = userService;
    }

    public void addUserController(){
        System.out.println("--UserController--");
//        原生写法
//        UserService userService = new UserServiceImpl();
//        userService.addUserService();

        userService.addUserService();
    }
}

三、创建service

package com.wsy.auto.service;

/**
 * @author within
 * @date 2023-02-09 11:09
 */
public interface UserService {
    public void addUserService();
}

四、创建类UserServiceImpl实现接口UserService

package com.wsy.auto.service;

import com.wsy.auto.dao.UserDao;
import com.wsy.auto.dao.UserDaoImpl;

/**
 * @author within
 * @date 2023-02-09 11:09
 */
public class UserServiceImpl implements UserService{

    private UserDao userDao;

    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }

    @Override
    public void addUserService() {
        System.out.println("--addUserService--");
//        UserDao userDao = new UserDaoImpl();
//        userDao.addUserDao();

        userDao.addUserDao();
    }
}

五、创建接口UserDao

package com.wsy.auto.dao;

/**
 * @author within
 * @date 2023-02-09 11:09
 */
public interface UserDao {
    public void addUserDao();
}

六、创建类UserDaoImpl实现接口UserDao

package com.wsy.auto.dao;

import com.wsy.factorybean.User;

/**
 * @author within
 * @date 2023-02-09 11:10
 */
public class UserDaoImpl implements UserDao {
    @Override
    public void addUserDao() {
        System.out.println("--addUserDao--");
    }
}

七、配置bean

使用bean标签的autowire属性设置自动装配效果
自动装配方式：byType
byType：根据类型匹配IOC容器中的某个兼容类型的bean，为属性自动赋值
若在IOC中，没有任何一个兼容类型的bean能够为属性赋值，则该属性不装配，即值为默认值null
若在IOC中，有多个兼容类型的bean能够为属性赋值，则抛出异常NoUniqueBeanDefinitionException

<?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">

<!--    根据类型自动装配-->
    <bean id="userController" class="com.wsy.auto.controller.UserController" autowire="byType">
    </bean>
    <bean id="userService" class="com.wsy.auto.service.UserServiceImpl" autowire="byType">
    </bean>
    <bean id="userDao" class="com.wsy.auto.dao.UserDaoImpl"/>
</beans>

自动装配方式：byName
byName：将自动装配的属性的属性名，作为bean的id在IOC容器中匹配相对应的bean进行赋值

<?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">

<!--    根据名称自动装配-->
    <bean id="userController" class="com.wsy.auto.controller.UserController" autowire="byName">
    </bean>
    <bean id="userService" class="com.wsy.auto.service.UserServiceImpl" autowire="byName">
    </bean>
    <bean id="userDao" class="com.wsy.auto.dao.UserDaoImpl"/>
</beans>

八、测试

class UserControllerTest {
    @Test
    public void testAutoByType(){
        ApplicationContext ac = new ClassPathXmlApplicationContext("bean-autoByType.xml");
        UserController userController = ac.getBean("userController",UserController.class);
        userController.addUserController();

    }

    @Test
    public void testAutoByName(){
        ApplicationContext ac = new ClassPathXmlApplicationContext("bean-autoByName.xml");
        UserController userController = ac.getBean("userController",UserController.class);
        userController.addUserController();

    }
}