Spring基于xml实现自动装配流程详解
热爱编程的小白白 人气:0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
①场景模拟
创建类 UserController
public class UserController { private UserService userService; public void setUserService(UserService userService) { this.userService = userService; } public void saveUser(){ userService.saveUser(); } }
创建接口 UserService
public interface UserService { void saveUser(); }
创建类 UserServiceImpl 实现接口 UserService
public class UserServiceImpl implements UserService { private UserDao userDao; public void setUserDao(UserDao userDao) { this.userDao = userDao; } @Override public void saveUser(){ userDao.saveUser(); } }
创建接口 UserDao
public interface UserDao { void saveUser(); }
创建类 UserDaoImpl 实现接口 UserDao
public class UserDaoImpl implements UserDao { @Override public void saveUser() { System.out.println("保存成功"); } }
②配置 bean
<bean id="userController" class="com.atguigu.spring.Controller.UserController"> <property name="userService" ref="userService"></property> </bean> <bean id="userService" class="com.atguigu.spring.Service.impl.UserServiceImpl"> <property name="userDao" ref="userDao"></property> </bean> <bean id="userDao" class="com.atguigu.spring.Dao.impl.UserDaoImpl"></bean>
③测试
@Test public void test2(){ ConfigurableApplicationContext ioc = new ClassPathXmlApplicationContext("spring-autowire-xml.xml"); UserController userController = ioc.getBean("userController", UserController.class); userController.saveUser(); }
④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
<bean id="userController" class="com.atguigu.spring.Controller.UserController" autowire="byType"> <!-- <property name="userService" ref="userService"></property>--> </bean> <bean id="userService" class="com.atguigu.spring.Service.impl.UserServiceImpl" autowire="byType"> <!-- <property name="userDao" ref="userDao"></property>--> </bean> <bean id="userDao" class="com.atguigu.spring.Dao.impl.UserDaoImpl"></bean>
⑤测试
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
<bean id="userController" class="com.atguigu.spring.Controller.UserController" autowire="byName"> <!-- <property name="userService" ref="userService"></property>--> </bean> <bean id="userService" class="com.atguigu.spring.Service.impl.UserServiceImpl" autowire="byName"> <!-- <property name="userDao" ref="userDao"></property>--> </bean> <bean id="userDao" class="com.atguigu.spring.Dao.impl.UserDaoImpl"></bean>
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