spring ioc container
只是转载bean的容器，
IoC , DI,
DI的方式
- through constructor arguments 构造函数
- arguments to a factory method, 工厂方式
- properties that are set, 属性注入
IoC 容器
- BeanFactory
- ApplicationContext
- WebApplicationCotext
- DefaultListableBeanFactory
- ClassPathXmlApplicationContext
- FileSystemXmlApplicationContext
ApplicationContext与BeanFactory的区别
- Easier integration with Spring’s AOP features，aop特性
- Message resource handling (for use in internationalization), 消息处理，主要是国际化
- Event publication , 事件发布, ApplicationEvent
- Application-layer specific contexts such as the WebApplicationContext for use in web applications. 扩展web的容器
spring ioc container
image.png
构建应用上下文的方式
- xml
- java
- java config
xml如何构建上下文
- 编写xml文件---services.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
https://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="..." class="...">
<!-- collaborators and configuration for this bean go here -->
</bean>
<bean id="..." class="...">
<!-- collaborators and configuration for this bean go here -->
</bean>
<!-- more bean definitions go here -->
</beans>
- 使用ClassPathXmlApplicationContext
// 支持多个xml资源, 拼接上去就可以了
ApplicationContext context = new ClassPathXmlApplicationContext("services.xml", "daos.xml");
// 构建2： classpath, 这个文件在resource文件夹下
ApplicationContext context = new ClassPathXmlApplicationContext("classpath:services.xml");
另一种写法
GenericApplicationContext context = new GenericApplicationContext();
new XmlBeanDefinitionReader(context).loadBeanDefinitions("services.xml", "daos.xml");
context.refresh();
java config构建
ApplicationContext context = new AnnotationConfigApplicationContext();
后台会将该类所在的路径作为基础扫描路径，当然包括本类会被扫描进。
还会扫描对应的注解@Configuration, @Bean, @Component, @Import, @DependsOn
另一种写法
public class JavaConfigTest {
public static void main(String[] arg) {
AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
ctx.register(AppConfig.class); // 将本类注入到IoC中
ctx.refresh(); // 刷新上下文，扫描并读取对应的class到beanDefinition中，完成上下文构建的工作
}
}
配置元数据
- Java-based configuration:
@Configuration, @Bean, @Import, and @DependsOn annotations. - Annotation-based configuration:
@Autowired,@Resource, @Inject - xml properties
<beans>, <bean>,
<property name="accountDao" ref="accountDao"/>
<import resource="resources/messageSource.xml"/>
例子
<beans>
// 注入其他xml文件
<import resource="services.xml"/>
<import resource="resources/messageSource.xml"/>
<import resource="/resources/themeSource.xml"/>
<bean id="bean1" class="..."/>
<bean id="bean2" class="..."/>
<bean id="petStore" class="org.springframework.samples.jpetstore.services.PetStoreServiceImpl">
// 注入其他属性
<property name="accountDao" ref="accountDao"/>
<property name="itemDao" ref="itemDao"/>
<!-- additional collaborators and configuration for this bean go here -->
</bean>
</beans>
获取Bean
简答方式就是通过getBean的方式
例子
T getBean(String name, Class<T> requiredType)
--------------------------------------------------------
// create and configure beans
ApplicationContext context = new ClassPathXmlApplicationContext("services.xml", "daos.xml");
// retrieve configured instance
PetStoreService service = context.getBean("petStore", PetStoreService.class);
// use configured instance
List<String> userList = service.getUsernameList();
写于 2020-08-12 23:42:11
PS: 若你觉得可以、还行、过得去、甚至不太差的话，可以“关注”一下，就此谢过!
