Spring IOC 注解方式

1.注解方式注入对象

在applicationContext.xml中添加<context:annotation-config/>，注入对象部分可以注释掉。

<?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:aop="http://www.springframework.org/schema/aop"
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
   http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
   http://www.springframework.org/schema/aop
   http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
   http://www.springframework.org/schema/tx
   http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
   http://www.springframework.org/schema/context     
   http://www.springframework.org/schema/context/spring-context-3.0.xsd">
  
    <context:annotation-config/>
    <bean name="c" class="com.how2java.pojo.Category">
        <property name="name" value="category 1" />
    </bean>
    <bean name="p" class="com.how2java.pojo.Product">
        <property name="name" value="product1" />
<!--         <property name="category" ref="c" /> -->
    </bean>
  
</beans>

然后在Bean类中对象前加入@Autowired就ok了。

此外，还可以用@Resource(name="")实现，用法和@Autowired一样，只不过需要加name参数，name=“bean name”，比如@Resource(name="c")，即注入category对象。

2.对Bean的注解

修改applicationContext.xml，什么都去掉，只新增：<context:component-scan base-package="com.how2java.pojo"/>，其作用是告诉Spring，bean都放在com.how2java.pojo这个包下。

<?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:aop="http://www.springframework.org/schema/aop"
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
   http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
   http://www.springframework.org/schema/aop
   http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
   http://www.springframework.org/schema/tx
   http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
   http://www.springframework.org/schema/context     
   http://www.springframework.org/schema/context/spring-context-3.0.xsd">
  
    <context:component-scan base-package="com.how2java.pojo"/>
     
</beans>

为类加上@Component注解，即表明此类是bean，此时就需要给变量赋值。在这里，还是为Product类注入Category对象。

public class TestSpring {

	public static void main(String[] args) {
		ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
		Product p=(Product)context.getBean("p");
		System.out.println(p.getCategory().getName());
	}
}

运行结果：