Spring之@Autowired问题
?Spring2之后，出现很多注解，这些注解让Spring的配置变得混乱起来，因此，别人力排Spring的注解。?注解引发的问题：1、缺乏明确的配置导致程序的依赖注入关系不明确。2、不利于模块化的装配。3、给维护带来麻烦，因为你要根据源代码找到依赖关系。4、通用性不好。如果你哪天抛开了Spring，换了别的Ioc容器，那么你的注解要一个个的删除。?但是很多傻X级的程序员还偶尔给你用点，或半用半不用，当你问及的时候，还一本正经的说某某某书上就是这么用的！！！如果你接手他的代码，会很郁闷。?这里写个例子，为的是看懂带注解的代码，不是推崇注解有多高级，真没必要。?package?lavasoft.springstu.anno;?
/**?
* 一个普通的Bean?
*?
* @author leizhimin 2009-12-23 10:40:38?
*/?
public?class?Foo {?
????????private?String name;?
????????public?Foo(String name) {?
????????????????this.name = name;?
????????}?
????????public?String getName() {?
????????????????return?name;?
????????}?
????????public?void?setName(String name) {?
????????????????this.name = name;?
????????}?
}?package?lavasoft.springstu.anno;?
import?org.springframework.beans.factory.annotation.Autowired;?
/**?
* Spring自动装配的注解?
*?
* @author leizhimin 2009-12-23 10:41:55?
*/?
public?class?Bar {?
????????@Autowired(required =?true)?
????????private?Foo foo;?
????????public?void?f1() {?
????????????????System.out.println(foo.getName());?
????????}?
}?<?xml?version="1.0"?encoding="UTF-8"?>?
<beans?xmlns="http://www.springframework.org/schema/beans"?
?????????????xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"?
?????????????xmlns:context="http://www.springframework.org/schema/context"?
???????????? xsi:schemaLocation="http://www.springframework.org/schema/beans?
???????????????????? http://www.springframework.org/schema/beans/spring-beans-2.5.xsd?
???????????????????? http://www.springframework.org/schema/context?
???????????????????? http://www.springframework.org/schema/context/spring-context-2.5.xsd">?
????????<!--?引用@Autowired必须定义这个bean?-->?
????????<bean?class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor"/>?
????????<!--?通过构造方法装配的Bean?-->?
????????<bean?id="foo"?class="lavasoft.springstu.anno.Foo">?
????????????????<constructor-arg?index="0"?type="java.lang.String"?value="aaaa"/>?
????????</bean>?
????????<!--?通过注解装配的Bean，我还以为它和Foo没关系呢?-->?
????????<bean?id="bar"?class="lavasoft.springstu.anno.Bar"/>?
</beans>?package?lavasoft.springstu.anno;?
import?org.springframework.context.ApplicationContext;?
import?org.springframework.context.support.ClassPathXmlApplicationContext;?
/**?
* 测试自动装配Bean?
*?
* @author leizhimin 2009-12-23 10:55:35?
*/?
public?class?Test1 {?
????????public?static?void?main(String[] args) {?
????????????????ApplicationContext ctx =?new?ClassPathXmlApplicationContext("lavasoft/springstu/anno/cfg1.xml");?
????????????????Bar bar = (Bar) ctx.getBean("bar");?
????????????????bar.f1();?
????????}?
}?运行结果：aaaa?
Process finished with exit code 0?从上面的代码中看到，Spring的注解使得配置文件的逻辑很混乱，如果项目中有大量的类似注解，那维护起来就很困难了。
