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