FactoryBean创建bean对象

下面是一个应用FactoryBean的例子 

<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"  
             xmlns:aop="http://www.springframework.org/schema/aop"  
             xmlns:tx="http://www.springframework.org/schema/tx"  
             xsi:schemaLocation="http://www.springframework.org/schema/beans  
                     http://www.springframework.org/schema/beans/spring-beans-3.0.xsd  
                     http://www.springframework.org/schema/context  
                     http://www.springframework.org/schema/context/spring-context-3.0.xsd  
                     http://www.springframework.org/schema/aop  
                     http://www.springframework.org/schema/aop/spring-aop-3.0.xsd  
                     http://www.springframework.org/schema/tx  
                     http://www.springframework.org/schema/tx/spring-tx-3.0.xsd">  
      
 <bean id="student" class="com.spring.bean.Student">    
  <property name="name" value="zhangsan" />    
 </bean>    
   
 <bean id="school" class="com.spring.bean.School">    
 </bean>   
   
 <bean id="factoryBeanPojo" class="com.spring.bean.FactoryBeanPojo">    
    <property name="type" value="student" />  
 </bean>   
</beans>    

  FactoryBean的实现类 

import org.springframework.beans.factory.FactoryBean;  
  
/**  
 * @author  作者 wangbiao 
 * @date 创建时间：2016年11月14日 上午11:19:31  
 * @parameter  
 * @return  
 */  
public class FactoryBeanPojo implements FactoryBean{  
    private String type;  
  
    @Override  
    public Object getObject() throws Exception {  
        if("student".equals(type)){  
            return new Student();             
        }else{  
            return new School();  
        }  
          
    }  
  
    @Override  
    public Class getObjectType() {  
        return School.class;  
    }  
  
    @Override  
    public boolean isSingleton() {  
        return true;  
    }  
  
    public String getType() {  
        return type;  
    }  
  
    public void setType(String type) {  
        this.type = type;  
    }  
      
}  

普通的bean 

/**  
 * @author  作者 wangbiao 
 * @date 创建时间：2016年11月14日 上午11:13:18  
 * @parameter  
 * @return  
 */  
public class School {  
    private String schoolName;  
    private String address;  
    private int studentNumber;  
    public String getSchoolName() {  
        return schoolName;  
    }  
    public void setSchoolName(String schoolName) {  
        this.schoolName = schoolName;  
    }  
    public String getAddress() {  
        return address;  
    }  
    public void setAddress(String address) {  
        this.address = address;  
    }  
    public int getStudentNumber() {  
        return studentNumber;  
    }  
    public void setStudentNumber(int studentNumber) {  
        this.studentNumber = studentNumber;  
    }  
    @Override  
    public String toString() {  
        return "School [schoolName=" + schoolName + ", address=" + address  
                + ", studentNumber=" + studentNumber + "]";  
    }  
}  

测试类 

import org.springframework.context.support.ClassPathXmlApplicationContext;  
  
import com.spring.bean.FactoryBeanPojo;  
  
/**  
 * @author  作者 wangbiao 
 * @date 创建时间：2016年11月14日 上午11:11:35  
 * @parameter  
 * @return  
 */  
public class FactoryBeanTest {  
    public static void main(String[] args){  
        String url = "com/spring/config/BeanConfig.xml";  
        ClassPathXmlApplicationContext cpxa = new ClassPathXmlApplicationContext(url);  
        Object school=  cpxa.getBean("factoryBeanPojo");  
        FactoryBeanPojo factoryBeanPojo= (FactoryBeanPojo) cpxa.getBean("&factoryBeanPojo");  
        System.out.println(school.getClass().getName());  
        System.out.println(factoryBeanPojo.getClass().getName());  
    }  
}  

 输出的结果：  

十一月 16, 2016 10:28:24 上午 org.springframework.context.support.AbstractApplicationContext prepareRefresh  
INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1e8ee5c0: startup date [Wed Nov 16 10:28:24 CST 2016]; root of context hierarchy  
十一月 16, 2016 10:28:24 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions  
INFO: Loading XML bean definitions from class path resource [com/spring/config/BeanConfig.xml]  
十一月 16, 2016 10:28:24 上午 org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons  
INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@35b793ee: defining beans [student,school,factoryBeanPojo]; root of factory hierarchy  
com.spring.bean.Student  
com.spring.bean.FactoryBeanPojo  

 从结果上可以看到当从IOC容器中获取FactoryBeanPojo对象的时候，用getBean(String BeanName)获取的确是Student对象，可以看到在FactoryBeanPojo中的type属性设置为student的时候，会在getObject()方法中返回Student对象。所以说从IOC容器获取实现了FactoryBean的实现类时，返回的却是实现类中的getObject方法返回的对象，要想获取FactoryBean的实现类，得在getBean(String BeanName)中的BeanName之前加上&,写成getBean(String &BeanName)。