context:annotation-config

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    <!-- enable processing of annotations such as @Autowired and @Configuration -->
    <context:annotation-config/>

Activates various annotations to be detected in bean classes: Spring‘s @Required and @Autowired, as well as JSR 250‘s @PostConstruct, @PreDestroy and @Resource (if available), JAX-WS‘s @WebServiceRef (if available), EJB3‘s @EJB (if available), and JPA‘s @PersistenceContext and @PersistenceUnit (if available). Alternatively, you may choose to activate the individual BeanPostProcessors for those annotations. Note: This tag does not activate processing of Spring‘s @Transactional or EJB3‘s @TransactionAttribute annotation. Consider the use of the <tx:annotation-driven> tag for that purpose. See javadoc for org.springframework.context.annotation.AnnotationConfigApplicationContext for information on code-based alternatives to bootstrapping annotation-driven support. from XML.

• @Required
• @Autowired
• @PostConstruct
• @PreDestroy
• @Resource
• @WebServiceRef
• @EJB
• @PersistenceContext
• @PersistenceUnit

JSR  Java Specification Request

EJB Enterprise JavaBeans

用途

激活注解类

注解类

@AutoWired

1. 使用spring的bean
2. required = true 是指必须在bean文件中存在
3. bean文件中的bean通过property为bean设值，java文件中必须存在setter
4. bean文件中的bean通过构造参数为bean设置时，不需要setter
5. 获取spring的某bean时，如果发现这个类中有AutoWired 则会在spring bean 资源中查找并注入，不需要setter

总结：

1. spring bean 相当于资源库，里面的资源存在依赖关系，依赖关系在java类中通过@AutoWired声明，强依赖的required=true ，弱依赖的required=false 。
2. spring bean 要达到的效果就是，依赖的反转控制 。 不需要new 不需要setter。

属性必须注入

@Required

　　@Required
    public void setName(String name) {
        this.name = name;
    }

　　<bean class="cn.zno.Person">
        <property name="name" value="xiaoming"></property>
    </bean>

context:annotation-config

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原文地址：http://www.cnblogs.com/zno2/p/4689681.html