写一篇最好懂的FactoryBean

小灰灰 2023-07-24 11:40 11阅读 0赞

## FactoryBean的作用主要是帮助动态代理注册到spring容器。 ##

## ***Person:*** ##

package com.mtons.mblog.modules.entity;
    
    /**
     * @author Administrator
     */
    public class Person {
        private String name;
        private String address;
        private int age;
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public String getAddress() {
            return address;
        }
    
        public void setAddress(String address) {
            this.address = address;
        }
    
        public int getAge() {
            return age;
        }
    
        public void setAge(int age) {
            this.age = age;
        }
    
        public Person() {
        }
    }

## ***PersonFactoryBean:*** ##

package com.mtons.mblog.modules.entity;
    
    import org.springframework.beans.factory.FactoryBean;
    import org.springframework.stereotype.Component;
    
    /**
     * @author Administrator
     */
    @Component(value = "personFactoryBean")
    public class PersonFactoryBean implements FactoryBean<Person> {
    
        private String personInfo = "gh2,22,address2";
    
    
        /**
         * 返回由FactoryBean创建的bean实例，如果isSingleton()返回true，则该实例会
         * 放到Spring容器中单实例缓存池中。
         * 通过factorybean代理对象注册给spring，否则代理对象没有文件无法注册给spring的
         * @return
         * @throws Exception
         */
        @Override
        public Person getObject() throws Exception {
            Person person =  new  Person () ;
            String []  infos =  personInfo.split ( "," ) ;
            person.setName(infos[0]);
            person.setAddress(infos[1]);
            person.setAge(Integer.parseInt(infos[2]));
            return person;
        }
    
    
        /**
         * 返回FactoryBean创建的bean类型。
         * @return
         */
        @Override
        public Class<Person> getObjectType() {
            return Person.class;
        }
    
        @Override
        public boolean isSingleton() {
            return true;
        }
    
        /**
         * 接受逗号分割符设置属性信息
         * @param personInfo
         */
        public void setPersonInfo(String personInfo) {
            this.personInfo = personInfo;
        }
    }

## ***FactortBeanlTest:*** ##

package com.mtons.mblog.modules.service.impl;
    
    import com.mtons.mblog.BootApplication;
    import com.mtons.mblog.modules.entity.Person;
    import com.mtons.mblog.modules.entity.PersonFactoryBean;
    import org.junit.Test;
    import org.junit.runner.RunWith;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.test.context.SpringBootTest;
    import org.springframework.context.ApplicationContext;
    import org.springframework.test.context.junit4.SpringRunner;
    
    /**
     * post service test
     *
     * @author saxing 2019/4/5 17:32
     */
    //@RunWith(SpringRunner.class)
    @SpringBootTest(classes = BootApplication.class)
    public class FactortBeanlTest {
    
        @Autowired
        PostServiceImpl postService;
    
    
            public static void main(String[] args) {
                ApplicationContext context = SpringApplication.run(BootApplication.class, args);
    
                /**
                 * 当调用getBean("personFactory") 时，Spring通过反射机制发现PersonFactoryBean实现了FactoryBean的接口，
                 * 这时Spring容器就调用接口方法PersonFactoryBean的getObject()方法返回。
                 * 如果希望获取PersonFactoryBean的实例，则需要在使用getBean(beanName) 方法时在beanName前显示的加上 "&"
                 * 前缀，例如getBean("&personFactory")。
                 */
                PersonFactoryBean personFactory = (PersonFactoryBean) context.getBean("&personFactoryBean");
                personFactory.setPersonInfo("gh2,address2,22");
                try {
                    Person person = personFactory.getObject();
                    //System.out.println("ggggggggggggggggggggggggggggggggggggggggggggggggggggg");
                    System.out.println(person.getName()+","+person.getAge()+","+person.getAddress());
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
    
    }

## ***调试条件断点：*** ##

![v2-dafb63788996a73d6104b391121cb7b7\_b.jpg][v2-dafb63788996a73d6104b391121cb7b7_b.jpg]

## ***输出：*** ##

***gh2,22,address2***

[v2-dafb63788996a73d6104b391121cb7b7_b.jpg]: /images/20230528/b427220209144c4c984c73e0ec1710f9.png