Spring Ioc 依赖查找

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

 <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

         http://www.springframework.org/schema/beans/spring-beans.xsd

       ">

     <!--实时查找-->

     <bean id="User" class="thinking.in.spring.ioc.overview.domain.User">

         <property name="id" value="1"/>

         <property name="name" value="小明"/>

     </bean>

     <!--延时查找-->

     <bean id="objectFactory" class="org.springframework.beans.factory.config.ObjectFactoryCreatingFactoryBean">

         <property name="targetBeanName" value="User"/>

     </bean>

 </beans>

2.启动spring应用上下文

 public class DenpendencyLookupDemo {

     public static void main(String[] args) {

         BeanFactory beanFactory=new ClassPathXmlApplicationContext("META-INF/dependency-Lookup-context.xml");

       //时实查找

         User user=(User) beanFactory.getBean("User");

         System.out.println("实时查找"+user.toString());

         //延时查找

       ObjectFactory<User>  objectFactory= (ObjectFactory<User>)beanFactory.getBean("objectFactory");

       User user1=objectFactory.getObject();

         System.out.println("延时查找"+user1.toString());

     }

 }

输出：

2.通过类型查找

单个Bean对象

集合Bean对象

 /**

      * 根据类型查找单个bean

      * @param beanFactory

      */

     private static void lookupSingleByType(BeanFactory beanFactory){

         User user2 = beanFactory.getBean(User.class);

         System.out.println("根据类型时实查找单一" + user2.toString());

     }

     /**

      * 查找多个bean

      */

     private static void lookupCollectionBtType (BeanFactory beanFactory){

         if (beanFactory instanceof ListableBeanFactory) {

             ListableBeanFactory listableBeanFactory = (ListableBeanFactory) beanFactory;

             Map<String, User> users = listableBeanFactory.getBeansOfType(User.class);

             System.out.println("查找多个bean" + users);

         }

     }

输出：

3.通过注解查找

 <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

         http://www.springframework.org/schema/beans/spring-beans.xsd

       ">

     <!--实时查找-->

     <bean id="User" class="thinking.in.spring.ioc.overview.domain.User">

         <property name="id" value="1"/>

         <property name="name" value="小明"/>

     </bean>

     <!--延时查找-->

     <bean id="objectFactory" class="org.springframework.beans.factory.config.ObjectFactoryCreatingFactoryBean">

         <property name="targetBeanName" value="User"/>

     </bean>

     <bean id="superUser" class="thinking.in.spring.ioc.overview.domain.SuperUser" parent="User" primary="true">

         <property name="number" value="1"/>

     </bean>

 </beans>

@Super注解

@Target({ElementType.TYPE}) @Retention(RetentionPolicy.RUNTIME) public @interface Super { }

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

 /**

      * 通过注解查找

      * @param beanFactory

      */

     private static  void lookupByAnnotatonType(BeanFactory beanFactory){

         if(beanFactory instanceof ListableBeanFactory){

             ListableBeanFactory listableBeanFactory=(ListableBeanFactory)beanFactory;
                       //根据注解查找

             Map<String,User> users=( Map)listableBeanFactory.getBeansWithAnnotation(Super.class);

             System.out.println("查找标注@Super 所有的User集合对象"+users);

         }

     }

输出：

只查找出标注了@Super注解且是User类型的Bean

巴特西

Spring Ioc 依赖查找

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