Spring ioc 有依赖查找和依赖注入，之前不太明白依赖查找是什么意思，翻了一大堆博客看了好多定义也不太清楚 ，后来看了小马哥视频，他通过代码演示，清楚地讲解了什么是 依赖查找以及几种依赖查找的方法，本文结合代码浅析一下Spring ioc的依赖查找，通过代码来更加形象的理解依赖查找。
1.根据bean名称查找：
-
实时查找
-
延时查找
1.配置xml文件 1 <beans xmlns="http://www.springframework.org/schema/beans"
2 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
3 xsi:schemaLocation="http://www.springframework.org/schema/beans
4 http://www.springframework.org/schema/beans/spring-beans.xsd
5 ">
6 <!--实时查找-->
7 <bean id="User" class="thinking.in.spring.ioc.overview.domain.User">
8 <property name="id" value="1"/>
9 <property name="name" value="小明"/>
10 </bean>
11 <!--延时查找-->
12 <bean id="objectFactory" class="org.springframework.beans.factory.config.ObjectFactoryCreatingFactoryBean">
13 <property name="targetBeanName" value="User"/>
14 </bean>
15 </beans>
2.启动spring应用上下文 1 public class DenpendencyLookupDemo {
2 public static void main(String[] args) {
3 BeanFactory beanFactory=new ClassPathXmlApplicationContext("META-INF/dependency-Lookup-context.xml");
4 //时实查找
5 User user=(User) beanFactory.getBean("User");
6 System.out.println("实时查找"+user.toString());
7 //延时查找
8 ObjectFactory<User> objectFactory= (ObjectFactory<User>)beanFactory.getBean("objectFactory");
9 User user1=objectFactory.getObject();
10 System.out.println("延时查找"+user1.toString());
11 }
12 }
输出：
2.通过类型查找
-
单个Bean对象
-
集合Bean对象
1 /**
2 * 根据类型查找单个bean
3 * @param beanFactory
4 */
5 private static void lookupSingleByType(BeanFactory beanFactory){
6
7 User user2 = beanFactory.getBean(User.class);
8 System.out.println("根据类型时实查找单一" + user2.toString());
9 }
10 /**
11 * 查找多个bean
12 */
13 private static void lookupCollectionBtType (BeanFactory beanFactory){
14 if (beanFactory instanceof ListableBeanFactory) {
15 ListableBeanFactory listableBeanFactory = (ListableBeanFactory) beanFactory;
16 Map<String, User> users = listableBeanFactory.getBeansOfType(User.class);
17 System.out.println("查找多个bean" + users);
18 }
19 }输出：
3.通过注解查找
1 <beans xmlns="http://www.springframework.org/schema/beans"
2 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
3 xsi:schemaLocation="http://www.springframework.org/schema/beans
4 http://www.springframework.org/schema/beans/spring-beans.xsd
5 ">
6 <!--实时查找-->
7 <bean id="User" class="thinking.in.spring.ioc.overview.domain.User">
8 <property name="id" value="1"/>
9 <property name="name" value="小明"/>
10 </bean>
11 <!--延时查找-->
12 <bean id="objectFactory" class="org.springframework.beans.factory.config.ObjectFactoryCreatingFactoryBean">
13 <property name="targetBeanName" value="User"/>
14 </bean>
15 <bean id="superUser" class="thinking.in.spring.ioc.overview.domain.SuperUser" parent="User" primary="true">
16 <property name="number" value="1"/>
17 </bean>
18 </beans>
@Super注解
1 @Target({ElementType.TYPE}) 2 @Retention(RetentionPolicy.RUNTIME) 3 public @interface Super { 4 }
SuperUser类
@Super
public class SuperUser extends User{
private String number;
public String getNumber() {
return number;
}
public void setNumber(String number) {
this.number = number;
}
@Override
public String toString() {
return "SuperUser{" +
"number='" + number + '\'' +
"} " + super.toString();
}
}
用法
1 /**
2 * 通过注解查找
3 * @param beanFactory
4 */
5 private static void lookupByAnnotatonType(BeanFactory beanFactory){
6 if(beanFactory instanceof ListableBeanFactory){
7 ListableBeanFactory listableBeanFactory=(ListableBeanFactory)beanFactory;
//根据注解查找
8 Map<String,User> users=( Map)listableBeanFactory.getBeansWithAnnotation(Super.class);
9 System.out.println("查找标注@Super 所有的User集合对象"+users);
10 }
11 }输出：
只查找出标注了@Super注解且是User类型的Bean
原文出处：https://www.cnblogs.com/Sherlockmmc/p/12494747.html
