Spring之FactoryBean

骑猪看日落 2022-03-06 07:50 234阅读 0赞

## 介绍 ##

*  以Bean结尾，表示它是一个Bean，不同于普通Bean的是：它是实现了FactoryBean接口的Bean，根据该Bean的ID从BeanFactory中获取的实际上是FactoryBean的getObject()返回的对象，而不是FactoryBean本身，如果要获取FactoryBean对象，请在id前面加一个&符号来获取。
 *  FactoryBean仍然是一个bean，但不同于普通bean，它的实现类最终也需要注册到BeanFactory中。它也是一种简单工厂模式的接口类，但是生产的是单一类型的对象，与BeanFactory生产多种类型对象不同。

## 源码 ##

package org.springframework.beans.factory;
    
    public interface FactoryBean<T> { 
    
    	/** * Return an instance (possibly shared or independent) of the object * managed by this factory. * 返回由FactoryBean管理的对象实例 */
    	T getObject() throws Exception;
    	
      /** * Return the type of object that this FactoryBean creates, * or {@code null} if not known in advance. * 返回对象实例的类型 */
    	Class<?> getObjectType();
    
    	/** * Is the object managed by this factory a singleton? */
    	boolean isSingleton();
    }

## 创建对象 ##

*  实体类People

public class People { 
        //在People中加入name属性
        private String name;
    
        public String getName(){ 
            return name;
        }
    
        public void setName(String name){ 
            this.name=name;
        }
    
        public void sleep(){ 
            System.out.println("睡觉了！");
        }
    }

*  自定义工厂Bean，实现FactoryBean接口

public class PeopleFactoryBean implements FactoryBean<People> { 
        private String name;
    
        public void setName(String name){ 
            this.name=name;
        }
    
        @Override
        public People getObject() throws Exception{ 
            People p=new People();
            p.setName(name);
            return p;
        }
    
        @Override
        public Class<?> getObjectType(){ 
            return People.class;
        }
    
        @Override
        public boolean isSingleton(){ 
            return true;
        }
    }

*  配置文件中配置

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参考文档：

1.  [https://blog.51cto.com/4247649/2118353][https_blog.51cto.com_4247649_2118353]

[https_blog.51cto.com_4247649_2118353]: https://blog.51cto.com/4247649/2118353