Spring Ioc 依賴查找

      Spring ioc 有依賴查找和依賴注入，之前不太明白依賴查找是什么意思，翻了一大堆博客看了好多定義也不太清楚 ，后來看了小馬哥視頻，他通過代碼演示，清楚地講解了什么是 依賴查找以及幾種依賴查找的方法，本文結合代碼淺析一下Spring ioc的依賴查找，通過代碼來更加形象的理解依賴查找。

    

   

1.根據bean名稱查找：        

    

• 實時查找

• 延時查找

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
      ">
    <!--實時查找-->
    <bean id="User" class="thinking.in.spring.ioc.overview.domain.User">
        <property name="id" value="1"/>
        <property name="name" value="小明"/>
    </bean>
    <!--延時查找-->
    <bean id="objectFactory" class="org.springframework.beans.factory.config.ObjectFactoryCreatingFactoryBean">
        <property name="targetBeanName" value="User"/>
    </bean>
</beans>

　

2.啟動spring應用上下文

public class DenpendencyLookupDemo {
    public static void main(String[] args) {
        BeanFactory beanFactory=new ClassPathXmlApplicationContext("META-INF/dependency-Lookup-context.xml");
      //時實查找
        User user=(User) beanFactory.getBean("User");
        System.out.println("實時查找"+user.toString());
        //延時查找
      ObjectFactory<User>  objectFactory= (ObjectFactory<User>)beanFactory.getBean("objectFactory");
      User user1=objectFactory.getObject();
        System.out.println("延時查找"+user1.toString());
    }
}

 

   輸出：

   

 

 

2.通過類型查找

     

• 單個Bean對象

• 集合Bean對象

     

/**
     * 根據類型查找單個bean
     * @param beanFactory
     */
    private static void lookupSingleByType(BeanFactory beanFactory){

        User user2 = beanFactory.getBean(User.class);
        System.out.println("根據類型時實查找單一" + user2.toString());
    }
    /**
     * 查找多個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("查找多個bean" + users);
        }
    }

輸出：

 

 

3.通過注解查找

<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
      ">
    <!--實時查找-->
    <bean id="User" class="thinking.in.spring.ioc.overview.domain.User">
        <property name="id" value="1"/>
        <property name="name" value="小明"/>
    </bean>
    <!--延時查找-->
    <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}) 2 @Retention(RetentionPolicy.RUNTIME) 3 public @interface Super { 4 } 

 

SuperUser類

@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

/**
     * 通過注解查找
     * @param beanFactory
     */
    private static  void lookupByAnnotatonType(BeanFactory beanFactory){
        if(beanFactory instanceof ListableBeanFactory){
            ListableBeanFactory listableBeanFactory=(ListableBeanFactory)beanFactory;
                       //根據注解查找
            Map<String,User> users=( Map)listableBeanFactory.getBeansWithAnnotation(Super.class);
            System.out.println("查找標注@Super 所有的User集合對象"+users);
        }
    }

輸出：

 

 只查找出標注了@Super注解且是User類型的Bean