Spring课程 Spring入门篇 4-3 Spring bean装配（下）之Autowired注解说明2 集合运用

课程链接：

本节主要讲了以下几块内容

1　　　　注解相关解析

2　　　　代码演练

集合for循环的使用

2.1　　list集合应用

2.2　　map集合应用

2.3　　集合排序（只对list有效，对map无效（list有序，map无序））

 

1　　　　注解相关解析

1.1　　autowired注解应用到集合属性可以提供所有特定类型的bean

1.2　　autowired可以提供集合中实体类的bean和子类的bean（继承，详情见下方代码）

autowired注解不能应用在Spring BeanPostProcessor或者BeanFactoryPostProcessor中，必须用xml或@Bean方式进行注解加载（否则会造成循环依赖）

2　　　　代码演练

2.1　　list集合应用

xml配置：

<?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.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">

<context:component-scan base-package="com.imooc.beanannotation"/>

</beans>

测试类：

package com.imooc.beaninvoker;

import org.junit.Test;

import com.imooc.beanannotation.injection.service.InjectionService;
import com.imooc.beanannotation.multibean.BeanInvoker;
import com.imooc.test.base.UnitTestBase;

public class TestBeanInvoker extends UnitTestBase{


    public TestBeanInvoker() {
        super("classpath*:spring-beaninvoker.xml");
    }
    
    @Test
    public void testBeanInvoker(){
        try {
            BeanInvoker bInvoker = super.getbean("beanInvoker");
            bInvoker.say();
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
    }
}

实体类：

package com.imooc.beanannotation.multibean;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component
public class BeanInvoker {
    @Autowired
    private List<BeanInterface> list;
    
    //
    public void say(){
        if(null!=list){
            for(BeanInterface bean :list){
                System.out.println(bean.getClass().getName());
            }
        }else{
            System.out.println("list is not null");
        }
        
    }

}

dao类：

package com.imooc.beanannotation.multibean;

public interface BeanInterface {

}

dao子类1：

package com.imooc.beanannotation.multibean;

import org.springframework.stereotype.Component;

@Component
public class BeanImplOne implements BeanInterface{

}

dao子类2：

package com.imooc.beanannotation.multibean;

import org.springframework.stereotype.Component;

@Component
public class BeanImplTwo implements BeanInterface{

}

打印结果：

三月 13, 2019 6:39:29 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@4a8927c8: startup date [Wed Mar 13 06:39:28 CST 2019]; root of context hierarchy
三月 13, 2019 6:39:29 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from URL [file:/F:/xiangmu3/Xin/FuQiang/Spring/ddwei-dao/target/classes/spring-beaninvoker.xml]
com.imooc.beanannotation.multibean.BeanImplOne
com.imooc.beanannotation.multibean.BeanImplTwo
三月 13, 2019 6:39:31 上午 org.springframework.context.support.ClassPathXmlApplicationContext doClose
信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@4a8927c8: startup date [Wed Mar 13 06:39:28 CST 2019]; root of context hierarchy

2.2　　map集合应用

实体类：

package com.imooc.beanannotation.multibean;

import java.util.List;
import java.util.Map;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component
public class BeanInvoker {
    @Autowired
    private List<BeanInterface> list;
    
    @Autowired
    private Map<String, BeanInterface> map;
    
    //
    public void say(){
        if(null!=list&&0!=list.size()){
            System.out.println("list...");
            for(BeanInterface bean :list){
                System.out.println(bean.getClass().getName());
            }
        }else{
            System.out.println("list is not null");
        }
        
        if(null!=map&&0!=map.size()){
            System.out.println("map...");
            for(Map.Entry<String,BeanInterface> entry :map.entrySet()){
                System.out.println(entry.getKey()+"  "+entry.getClass().getName());
            }
        }else{
            System.out.println("Map<String,BeanInterface> map is null");
        }
        
    }

}

其他类完全相同：

打印日志：

三月 18, 2019 6:52:15 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@7292e1b2: startup date [Mon Mar 18 06:52:15 CST 2019]; root of context hierarchy
三月 18, 2019 6:52:16 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from URL [file:/F:/xiangmu3/Xin/FuQiang/Spring/ddwei-dao/target/classes/spring-beaninvoker.xml]
list...
com.imooc.beanannotation.multibean.BeanImplOne
com.imooc.beanannotation.multibean.BeanImplTwo
map...
beanImplOne  java.util.LinkedHashMap$Entry
beanImplTwo  java.util.LinkedHashMap$Entry
三月 18, 2019 6:52:20 上午 org.springframework.context.support.ClassPathXmlApplicationContext doClose
信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@7292e1b2: startup date [Mon Mar 18 06:52:15 CST 2019]; root of context hierarchy

2.3　　集合排序（只对list有效，对map无效（list有序，map无序））

dao子类1：

package com.imooc.beanannotation.multibean;

import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

@Order(2)
@Component
public class BeanImplOne implements BeanInterface{

}

dao子类2：

package com.imooc.beanannotation.multibean;

import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

@Order(1)
@Component
public class BeanImplTwo implements BeanInterface{

}

其他完全一致：

打印日志：

三月 18, 2019 7:00:13 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@e41a882: startup date [Mon Mar 18 07:00:13 CST 2019]; root of context hierarchy
三月 18, 2019 7:00:13 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from URL [file:/F:/xiangmu3/Xin/FuQiang/Spring/ddwei-dao/target/classes/spring-beaninvoker.xml]
list...
三月 18, 2019 7:00:14 上午 org.springframework.context.support.ClassPathXmlApplicationContext doClose
信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@e41a882: startup date [Mon Mar 18 07:00:13 CST 2019]; root of context hierarchy
com.imooc.beanannotation.multibean.BeanImplTwo
com.imooc.beanannotation.multibean.BeanImplOne
map...
beanImplOne  java.util.LinkedHashMap$Entry
beanImplTwo  java.util.LinkedHashMap$Entry