<?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:c="http://www.springframework.org/schema/c"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:jdbc="http://www.springframework.org/schema/jdbc"
	xmlns:jee="http://www.springframework.org/schema/jee"
	xmlns:mvc="http://www.springframework.org/schema/mvc"
	xmlns:p="http://www.springframework.org/schema/p"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xmlns:util="http://www.springframework.org/schema/util"
	xmlns:websocket="http://www.springframework.org/schema/websocket"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd
		http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-4.3.xsd
		http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-4.3.xsd
		http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.3.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.3.xsd
		http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.3.xsd
		http://www.springframework.org/schema/websocket http://www.springframework.org/schema/websocket/spring-websocket-4.3.xsd">


         <bean id="autotest" class="autotest" autowire="constructor">  
            
         </bean>
         
         <!-- 
         當 Spring 容器啟動時，AutowiredAnnotationBeanPostProcessor 將掃描 Spring 容器中所有 Bean，當發現 Bean 中擁有 @Autowired 註釋時就找到和其匹配(預設按型別匹配)的 Bean，並注入到對應的地方中去
          -->
         <bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor"/>
        
          <bean id="person" class="Person">  
            <property name="age" value="21"></property>  
            <property name="name" value="李躍"></property>  
             <property name="sex" value="男"></property>  
         </bean>  

  
</beans>
 

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class autotest {  
          
     @Autowired//這裡用了這個註釋就省去了構造方法或者get，set方法來設定person屬性  
    private Person person;
     
  

	public void fun(){  
           ConfigurableApplicationContext cf=new ClassPathXmlApplicationContext("spring-mvc.xml");      
           autotest autotest=(autotest)cf.getBean("autotest");   
           System.out.println(autotest);  
           System.out.println(autotest.person);  
     }  
       
        public static void main(String args[]){  
            new autotest().fun();  
        }  
}  
 

否則如下

<?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:c="http://www.springframework.org/schema/c"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:jdbc="http://www.springframework.org/schema/jdbc"
	xmlns:jee="http://www.springframework.org/schema/jee"
	xmlns:mvc="http://www.springframework.org/schema/mvc"
	xmlns:p="http://www.springframework.org/schema/p"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xmlns:util="http://www.springframework.org/schema/util"
	xmlns:websocket="http://www.springframework.org/schema/websocket"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd
		http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-4.3.xsd
		http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-4.3.xsd
		http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.3.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.3.xsd
		http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.3.xsd
		http://www.springframework.org/schema/websocket http://www.springframework.org/schema/websocket/spring-websocket-4.3.xsd">


         <bean id="autotest" class="autotest" >  
            <property name="person" ref="person"></property>  
         </bean>
         
      
          <bean id="person" class="Person">  
            <property name="age" value="21"></property>  
            <property name="name" value="李躍"></property>  
             <property name="sex" value="男"></property>  
         </bean>  

  
</beans>
 

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class autotest {  
          
    
    private Person person;
     
    public Person getPerson() {
		return person;
	}

	public void setPerson(Person person) {
		this.person = person;
	}

	public void fun(){  
           ConfigurableApplicationContext cf=new ClassPathXmlApplicationContext("spring-mvc.xml");      
           autotest autotest=(autotest)cf.getBean("autotest");   
           System.out.println(autotest);  
           System.out.println(autotest.person);  
     }  
       
        public static void main(String args[]){  
            new autotest().fun();  
        }  
}  

2.對註解Autowired放在setter方法上的情況，這種情況要注意幾種情況，先看程式碼

<?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:c="http://www.springframework.org/schema/c"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:jdbc="http://www.springframework.org/schema/jdbc"
	xmlns:jee="http://www.springframework.org/schema/jee"
	xmlns:mvc="http://www.springframework.org/schema/mvc"
	xmlns:p="http://www.springframework.org/schema/p"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xmlns:util="http://www.springframework.org/schema/util"
	xmlns:websocket="http://www.springframework.org/schema/websocket"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd
		http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-4.3.xsd
		http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-4.3.xsd
		http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.3.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.3.xsd
		http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.3.xsd
		http://www.springframework.org/schema/websocket http://www.springframework.org/schema/websocket/spring-websocket-4.3.xsd">


         <bean id="autotest" class="autotest"/>  
          
         <!-- 
                            當 Spring 容器啟動時，AutowiredAnnotationBeanPostProcessor 將掃描 Spring 容器中所有 Bean，當發現 Bean 中擁有 @Autowired 註釋時就找到和其匹配(預設按型別匹配)的 Bean，並注入到對應的地方中去
          -->
        <bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor"/>
         
         <bean id="person" class="Person">  
             <property name="age" value="21"></property>  
             <property name="name" value="李躍"></property>  
             <property name="sex" value="男"></property>  
         </bean>  

  
</beans>

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

//A:
public class autotest{  
//C:    
private Person person;
	
	public void fun(){  
           ConfigurableApplicationContext cf=new ClassPathXmlApplicationContext("spring-mvc.xml");      
           autotest autotest=(autotest)cf.getBean("autotest");   
          
           System.out.println(autotest.person); //[email protected]
           System.out.println(this); //[email protected]
           System.out.println(autotest); //[email protected]
           System.out.println(this.person);//null,
           
     }  
       
    public Person getPerson() {
    	System.out.println(person); 
		return person;
	}
    
    @Autowired
	public void setPerson(Person person) {
		this.person = person;
	}

   public static void main(String args[]){  
	       new autotest().fun(); // (new autotest()==B)呼叫A==b.a.fun() 
        }  
}  

上面要注意區分幾個物件this,autotest,是有區別的，對this和autotest來說person都是他們的屬性，但是真正通過註解和配置檔案配合工作的卻是autotest，所以對於註解在setter方法上的情況，只有autotest.person不是空，單獨的this.person或者new 一個物件.person是空的。這裡我是來自http://blog.csdn.net/badboy_qiao/article/details/52713257最後總結的啟發。

結論：注入的物件，只會呼叫空參建構函式，且這個物件的所有屬性都是預設值，自己手動賦予的值不會被使用，

所以在A中的C類，在B中呼叫A的時候，建立的A物件的屬性都是預設值，所以A物件雖然有了，但是A的屬性C卻是null，所以在B中直接this.a.c.method()是會報null指標異常的，且是c是null的發生原因。

解決方式：C在A中新增get方法，然後B中使用a.getC()即可獲得c的物件，且c的物件也是spring注入的。

再順便談一個問題做下記錄,為了更好理解上面的幾句話看下面物件的輸出，this物件始終和第一次真正new出來的物件（autotest test=new autotest();不是new autotest();）是同一個東西

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

//A:
public class autotest{  
//C:    
private Person person;
	
	public void fun(){  
           ConfigurableApplicationContext cf=new ClassPathXmlApplicationContext("spring-mvc.xml");      
           autotest autotest=(autotest)cf.getBean("autotest");   
           autotest test=new autotest();
           System.out.println(test);//D [email protected] 
           System.out.println(this); //C [email protected]
           System.out.println(this.person);//null
           System.out.println(test.person);//null
           System.out.println(autotest.person);//[email protected]
     }  
       
    public Person getPerson() {
    	System.out.println(person); 
		return person;
	}
    
    @Autowired
	public void setPerson(Person person) {
		this.person = person;
	}

   public static void main(String args[]){ 
	      System.out.println(new autotest());//B [email protected]
	      autotest test=new autotest();
	      System.out.println(test.person);//null
	      System.out.println(test);//A [email protected]
	      test.fun(); 
        }  
}  

還有一個地方就是如果所有bean在容器中已經存在，那麼我們某個Java類中如果用到其它物件，我們可以省去在當前這個Java類的bean配置檔案中用property來配置它包含的屬性，它會自動注入這些屬性物件，直接使用就行。

如下面這裡使用到這個物件

這個類的bean中可以直接

<bean name="shopManagerController" class="com.xxxx.ShopManagerController"">

</bean>不用property來配置shopManagerService，可以省去，用了resource註解settter方法也可以省去,但是要在介面實現類或者類的上面使用@Service("resource右邊的name或者介面或者類的首字母小寫")

<!-- 把標記了@Controller等註解的類轉換為bean -->
<context:component-scan base-package="com.XXX" />

XML中也不需要配置controller的bean

1.bean的例項化，個人理解

1.通過自動掃包，註解方式配置bean,不用繁瑣的在xml檔案中進行配置很多bean，
這種bean當tomcat啟動專案的時候，bean物件是null,當我呼叫相應方法時，
它會首先被例項化然後被呼叫，如下面只有當我我呼叫selectpage方法時，handle通過afterPropertiesSet方法呼叫子類的
的initService方法被例項化，然後handle物件不再為空


protected abstract void initService();


@Override
public void afterPropertiesSet() throws Exception {
initService();
System.out.println("初始化handle"+handle);
if (handle == null) {
logger.info("Generic handle is not set. Please set it in the initService method if handle access is desired!");
}


}




public SearchCriteria<T> selectPage(SearchCriteria<T> sc) {
return handle.selectPage(sc);
}




2.xml中配置bean,這種bean當tomcat啟動專案的時候，bean物件就被例項化放入到一個容器中,當我呼叫相應方法時，
它會被直接取出來，如上面當我我呼叫selectpage方法時，不需要再進行afterPropertiesSet方法呼叫子類的
的initService方法對handle進行例項化，然後handle物件不會為空。