springboot beanfactory与factorybean

た入场券 2022-08-29 09:41 181阅读 0赞

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## springboot beanfactory与factorybean ##

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**相关类与接口**

**BeanFactory：对象工厂**

public interface BeanFactory {
        String FACTORY_BEAN_PREFIX = "&";
    
        Object getBean(String var1) throws BeansException;
        Object getBean(String var1, Object... var2) throws BeansException;
    
        <T> T getBean(String var1, Class<T> var2) throws BeansException;
        <T> T getBean(Class<T> var1) throws BeansException;
        <T> T getBean(Class<T> var1, Object... var2) throws BeansException;
    
        <T> ObjectProvider<T> getBeanProvider(Class<T> var1);
        <T> ObjectProvider<T> getBeanProvider(ResolvableType var1);
    
        boolean containsBean(String var1);
    
        boolean isSingleton(String var1) throws NoSuchBeanDefinitionException;
        boolean isPrototype(String var1) throws NoSuchBeanDefinitionException;
    
        boolean isTypeMatch(String var1, ResolvableType var2) throws NoSuchBeanDefinitionException;
        boolean isTypeMatch(String var1, Class<?> var2) throws NoSuchBeanDefinitionException;
    
        @Nullable
        Class<?> getType(String var1) throws NoSuchBeanDefinitionException;
    
        @Nullable
        Class<?> getType(String var1, boolean var2) throws NoSuchBeanDefinitionException;
    
        String[] getAliases(String var1);
    }

**ApplicationContext：继承BeanFactory，spring 中常用该接口获取对象实例**

public interface ApplicationContext extends EnvironmentCapable, ListableBeanFactory, HierarchicalBeanFactory, MessageSource, ApplicationEventPublisher, ResourcePatternResolver {
        @Nullable
        String getId();
    
        String getApplicationName();
        String getDisplayName();
    
        long getStartupDate();
    
        @Nullable
        ApplicationContext getParent();
    
        AutowireCapableBeanFactory getAutowireCapableBeanFactory() throws IllegalStateException;
    }

**ListableBeanFactory：继承BeanFactory接口**

public interface ListableBeanFactory extends BeanFactory {
    
        boolean containsBeanDefinition(String var1);
    
        int getBeanDefinitionCount();
        String[] getBeanDefinitionNames();
    
        <T> ObjectProvider<T> getBeanProvider(Class<T> var1, boolean var2);
        <T> ObjectProvider<T> getBeanProvider(ResolvableType var1, boolean var2);
    
        String[] getBeanNamesForType(ResolvableType var1);
        String[] getBeanNamesForType(ResolvableType var1, boolean var2, boolean var3);
        String[] getBeanNamesForType(@Nullable Class<?> var1);
        String[] getBeanNamesForType(@Nullable Class<?> var1, boolean var2, boolean var3);
    
        <T> Map<String, T> getBeansOfType(@Nullable Class<T> var1) throws BeansException;
        <T> Map<String, T> getBeansOfType(@Nullable Class<T> var1, boolean var2, boolean var3) throws BeansException;
    
        String[] getBeanNamesForAnnotation(Class<? extends Annotation> var1);
        Map<String, Object> getBeansWithAnnotation(Class<? extends Annotation> var1) throws BeansException;
    
        @Nullable
        <A extends Annotation> A findAnnotationOnBean(String var1, Class<A> var2) throws NoSuchBeanDefinitionException;
    }

**HierarchicalBeanFactory：继承BeanFactory接口**

public interface HierarchicalBeanFactory extends BeanFactory {
        @Nullable
        BeanFactory getParentBeanFactory();
    
        boolean containsLocalBean(String var1);
    }

**FactoryBean：自定义对象创建过程**

public interface FactoryBean<T> {
        String OBJECT_TYPE_ATTRIBUTE = "factoryBeanObjectType";
    
        @Nullable
        T getObject() throws Exception; 
                      //CustomFactoryBean实现FactoryBean接口，实例名称为：customFactoryBean
                      //getObject返回对象：object
                      //application.getBean("customFactoryBean")返回object
                      //application.getBean("&customFactoryBean")返回customFactoryBean实例
    
        @Nullable
        Class<?> getObjectType();
    
        default boolean isSingleton() {
            return true;
        }
    }

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**示例**

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**pojo 层**

**Person**

@Data
    public class Person {
    
        private Integer id;
        private String name;
        private Integer age;
    }

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**config 层**

**DataConfig**

@Configuration
    public class DataConfig {
    
        @Bean
        public Person initPerson(){
            Person person=new Person();
            person.setId(1);
            person.setName("瓜田李下");
            person.setAge(20);
    
            return person;
        }  //person对象实例name：initPerson
    }

**CustomfactoryBean**

@Component
    public class CustomFactoryBean implements FactoryBean<Person> {
    
        @Override
        public Class<?> getObjectType() {
            return Person.class;
        }
    
        @Override
        public Person getObject() throws Exception {
            Person person=new Person();
            person.setId(2);
            person.setName("海贼王");
            person.setAge(20);
    
            return person;
        }  //person实例会注入容器中，name：customFactoryBean
    }

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**controller 层**

**HelloController**

@RestController
    public class HelloController {
    
        @Resource
        private ApplicationContext applicationContext;
    
        @Resource
        private List<Person> personList;
    
        @Resource(name = "&customFactoryBean")
        private CustomFactoryBean customFactoryBean;
    
        @Resource(name = "customFactoryBean")
        private Person person;
    
        @RequestMapping("/hello")
        public String hello() throws Exception{
            System.out.println(applicationContext.getBean("initPerson"));
            //System.out.println(applicationContext.getBean(Person.class));
            System.out.println(applicationContext.getBean("customFactoryBean"));
            System.out.println(applicationContext.getBean("&customFactoryBean")+"\n");
    
            personList.forEach(System.out::println);
            System.out.println(customFactoryBean.getObject());
            System.out.println(person);
    
            return "success";
        }
    }

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**使用测试**

**localhost:8080/hello，控制台输出：**

Person(id=1, name=瓜田李下, age=20)
    Person(id=2, name=海贼王, age=20)
    com.example.demo.config.CustomFactoryBean@88aa1a2
    
    Person(id=2, name=海贼王, age=20)
    Person(id=1, name=瓜田李下, age=20)
    Person(id=2, name=海贼王, age=20)
    Person(id=2, name=海贼王, age=20)