Spring 依赖注入与依赖查找来源的区别

古城微笑少年丶 2022-11-06 10:56 87阅读 0赞

依赖查找的来源：

*  xml <bean>
 *  BeanDefinitionRegistry\#registerBeanDefinition
 *  SingletonBeanRegistry\#registerSingleton
 *  注解 @Bean
 *  @Component 派生出的注解，如  @Configuration
 *  IoC 容器内建 bean。如 ConfigurationClassPostProcessor,AutowiredAnnotationBeanPostProcessor,CommonAnnotationBeanPostProcessor,EventListenerMethodProcessor,Environment,systemProperties — java.util.Properties,systemEnvironment — java.util.Map,MessageSource,LifecycleProcessor,ApplicationEventMulticaster

依赖注入的来源：

*  依赖查找的来源
 *  外部化配置，如 @Value 注解获取的 properties 文件的属性值
 *  ConfigurableListableBeanFactory\#registerResolvableDependency

测试代码：

spring xml 配置

config.properties

echo=你好

User 类

package constxiong;
    
    public class User {
    
        private Integer id;
    
        public Integer getId() {
            return id;
        }
    
        public void setId(Integer id) {
            this.id = id;
        }
    }

Bean 类

package constxiong;
    
    import javax.annotation.Resource;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.context.annotation.ConfigurationClassPostProcessor;
    import org.springframework.context.annotation.Lazy;
    import org.springframework.stereotype.Component;
    
    @Component
    @Lazy
    public class Bean {
    	
    	// xml <bean>
    	@Resource(name="user")
    	private User user;
    	
    	//BeanDefinitionRegistry#registerBeanDefinition
    	@Resource(name="user1")
    	private User user1;
    	
    	//SingletonBeanRegistry#registerSingleton
    	@Resource(name="user2")
    	private User user2;
    	
    	//注解 @Bean
    	@Resource(name="user3")
    	private User user3;
    	
    	//注解 @Configuration，@Component 派生出的注解
    	@Autowired
    	private Test test;
    	
    	//IoC 容器内建 bean
    	@Autowired
    	private ConfigurationClassPostProcessor configurationClassPostProcessor;
    	
    	//ConfigurableListableBeanFactory#registerResolvableDependency
    	@Autowired(required=false)
    	private String who;
    	
    	//外部化配置，config.properties 文件中的配置值
    	@Value("${echo}")
    	private String echo;
    
    	public String toString() {
    		return "Bean [user=" + user + ",
     user1=" + user1 + ",
     user2=" + user2
    				+ ",
     user3=" + user3 + ",
     test=" + test
    				+ ",
     configurationClassPostProcessor="
    				+ configurationClassPostProcessor + ",
     who=" + who + ",
     echo="
    				+ echo + "]";
    	}
    	
    }

测试类

package constxiong;
    
    import org.springframework.beans.factory.support.BeanDefinitionBuilder;
    import org.springframework.beans.factory.support.DefaultListableBeanFactory;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.ConfigurationClassPostProcessor;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    /**
     * 测试依赖查找、依赖注入来源的区别
     * 
     * @author ConstXiong
     */
    @Configuration
    public class Test {
    	
    	public static void main(String[] args) {
    		System.out.println("依赖查找");
    		lookup();//依赖查找
    		System.out.println();
    		System.out.println("依赖注入");
    		inject();//依赖注入
    	}
    
    	/**
    	 * 依赖查找的来源
    	 */
    	private static void lookup() {
    		ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("META-INF/spring-lookup-inject-source.xml");
    		
    		((DefaultListableBeanFactory)context.getBeanFactory()).registerBeanDefinition("user1", 
    				BeanDefinitionBuilder.rootBeanDefinition(User.class).getBeanDefinition());
    		
    		context.getBeanFactory().registerSingleton("user2", new User());
    		
    		// xml <bean>
    		User user = context.getBean("user", User.class);
    		System.out.println(user);
    		
    		//BeanDefinitionRegistry#registerBeanDefinition
    		User user1 = context.getBean("user1", User.class);
    		System.out.println(user1);
    		
    		//SingletonBeanRegistry#registerSingleton
    		User user2 = context.getBean("user2", User.class);
    		System.out.println(user2);
    		
    		//注解 @Bean
    		User user3 = context.getBean("user3", User.class);
    		System.out.println(user3);
    		
    		//注解 @Configuration，@Component 派生出的注解
    		Test test = context.getBean("test", Test.class);
    		System.out.println(test);
    		
    		//IoC 容器内建 bean
    		//ConfigurationClassPostProcessor
    		//AutowiredAnnotationBeanPostProcessor
    		//CommonAnnotationBeanPostProcessor
    		//EventListenerMethodProcessor
    		//Environment
    		//systemProperties — java.util.Properties
    		//systemEnvironment — java.util.Map
    		//MessageSource
    		//LifecycleProcessor
    		//ApplicationEventMulticaster
    		ConfigurationClassPostProcessor innerBean = context.getBean(ConfigurationClassPostProcessor.class);
    		System.out.println(innerBean);
    		
    	}
    	
    	@Bean
    	public static User user3() {
    		return new User();
    	}
    	
    	/**
    	 * 依赖注入的来源
    	 */
    	private static void inject() {
    		ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("META-INF/spring-lookup-inject-source.xml");
    		context.addBeanFactoryPostProcessor(beanFactory -> {
    			beanFactory.registerResolvableDependency(String.class, "constxiong");
    		});
    		context.refresh();
    		((DefaultListableBeanFactory)context.getBeanFactory()).registerBeanDefinition("user1", 
    				BeanDefinitionBuilder.rootBeanDefinition(User.class).getBeanDefinition());
    		
    		context.getBeanFactory().registerSingleton("user2", new User());
    		constxiong.Bean bean = context.getBean("bean", constxiong.Bean.class);
    		System.out.println(bean);
    	}
    
    }

打印结果

依赖查找
    constxiong.User@3bcd05cb
    constxiong.User@3b6d844d
    constxiong.User@36804139
    constxiong.User@20bd8be5
    constxiong.Test$$EnhancerBySpringCGLIB$$d5eb59ff@730d2164
    org.springframework.context.annotation.ConfigurationClassPostProcessor@7068e664
    
    依赖注入
    Bean [user=constxiong.User@46b61c56,
     user1=constxiong.User@2e48362c,
     user2=constxiong.User@1efe439d,
     user3=constxiong.User@be68757,
     test=constxiong.Test$$EnhancerBySpringCGLIB$$d5eb59ff@7d446ed1,
     configurationClassPostProcessor=org.springframework.context.annotation.ConfigurationClassPostProcessor@12d2ce03,
     who=constxiong,
     echo=你好]

[完整代码：020-spring-lookup-inject-source][020-spring-lookup-inject-source]

--------------------

### 【Java学习资源】整理推荐 ###

*  [自定义 Bean 作用域][Bean]
 *  [Bean 的作用域][Bean 1]
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 *  [Spring 依赖注入与依赖查找来源的区别][Spring]
 *  [Spring 依赖注入的处理过程与 DependencyDescriptor 的说明][Spring _ DependencyDescriptor]
 *  [Spring 各种 Aware 接口回调注入][Spring _ Aware]
 *  [Spring Bean 生命周期内的 Exception 复现][Spring Bean _ Exception]
 *  [Spring 内建 Bean][Spring _ Bean]
 *  [Spring Bean 的别名][Spring Bean]
 *  [Spring Bean 未指定名称的命名规则][Spring Bean 1]
 *  [Bean 何时被 GC][Bean _ GC]
 *  [Spring Bean 延迟加载][Spring Bean 2]
 *  [ObjectFactory 与 BeanFactory 的区别][ObjectFactory _ BeanFactory]
 *  [Bean 销毁的方式与顺序][Bean 2]
 *  [Bean 初始化的方式与顺序][Bean 3]
 *  [Bean 的实例化方式][Bean 4]
 *  [Bean的注册方式][Bean 5]
 *  [什么是 BeanDefinition？][BeanDefinition]
 *  [Spring IoC 容器启动时做了什么？][Spring IoC]
 *  [BeanFactory 与 FactoryBean 的区别][BeanFactory _ FactoryBean]
 *  [BeanFactory 与 ApplicationContext 的区别][BeanFactory _ ApplicationContext]
 *  [Spring IoC 依赖注入的实现方式][Spring IoC 1]
 *  [Spring IoC 依赖注入(支持哪些数据类型？)][Spring IoC 2]
 *  [Spring bean 依赖查找][Spring bean]
 *  [Spring-IoC][]
 *  [Spring 的核心特性][Spring 1]

--------------------

### 【Java面试题与答案】整理推荐 ###

*  [基础与语法][Link 1]
 *  [集合][Link 2]
 *  [网络编程][Link 3]
 *  [并发编程][Link 4]
 *  [Web][]
 *  [安全][Link 5]
 *  [设计模式][Link 6]
 *  [框架][Link 7]
 *  [算法与数据结构][Link 8]
 *  [异常][Link 9]
 *  [文件解析与生成][Link 10]
 *  [Linux][]
 *  [MySQL][]
 *  [Oracle][]
 *  [Redis][]
 *  [Dubbo][]

[020-spring-lookup-inject-source]: https://github.com/ConstXiong/toy/tree/master/spring-study/020-spring-lookup-inject-source
[Bean]: https://www.javanav.com/val/3fdc7ac3bd034a5ab7040e23f37153fa.html
[Bean 1]: https://www.javanav.com/val/59101a7207864f4aa971e5c48b592c77.html
[maven _ tomcat _ jar _ web]: https://www.javanav.com/val/b1f4691bd6ba488a80e3bdfcefdec33c.html
[Spring]: https://www.javanav.com/val/a9569837e1bc4df9aeac0e6cbf96bf06.html
[Spring _ DependencyDescriptor]: https://www.javanav.com/val/152161d266a94fd38efb365a78d8f9a3.html
[Spring _ Aware]: https://www.javanav.com/val/089b3993c8bc4dec891ea677c104c5e4.html
[Spring Bean _ Exception]: https://www.javanav.com/val/2b31b7061b3342c0a67f8d7fc7373ed3.html
[Spring _ Bean]: https://www.javanav.com/val/92f9e0951b19454196b645bb3cb1a0b9.html
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[Spring Bean 2]: https://www.javanav.com/val/b197550be7ba4bd8b4d82f6835d1abb1.html
[ObjectFactory _ BeanFactory]: https://www.javanav.com/val/016d62d99b0148feaf13529a841f4e46.html
[Bean 2]: https://www.javanav.com/val/a5a7f97894f9499b90e27dbd98124a1c.html
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[BeanDefinition]: https://www.javanav.com/val/e82279480ec24184bcaf723a50ef08b3.html
[Spring IoC]: https://www.javanav.com/val/d382c8380fc2480788a35a7e671b5e9b.html
[BeanFactory _ FactoryBean]: https://www.javanav.com/val/173e873a2c98499a8a08a13b4f88ae10.html
[BeanFactory _ ApplicationContext]: https://www.javanav.com/val/bbc2c9580b7045e583855925d5f1a50b.html
[Spring IoC 1]: https://www.javanav.com/val/a835e6c709ea439ebb21a80f1bf77926.html
[Spring IoC 2]: https://www.javanav.com/val/e377beac22644c2c85308079b239a0fd.html
[Spring bean]: https://www.javanav.com/val/7f8c2e1f24db46e79bc4b9b04f9ad715.html
[Spring-IoC]: https://www.javanav.com/val/a412668efda74412a13f6df9a6d2c714.html
[Spring 1]: https://www.javanav.com/val/6eac12a548ea40c68ff64b1af307563a.html
[Link 1]: https://www.javanav.com/interview/93b0069472fd479393006c0e73043fc4.html
[Link 2]: https://www.javanav.com/interview/4147d95e693945e7a50345fd33ec817e.html
[Link 3]: https://www.javanav.com/interview/68a57ffc78de4133bb890bdd502ac418.html
[Link 4]: https://www.javanav.com/interview/36a24fa3258e45c89873f474ce914912.html
[Web]: https://www.javanav.com/interview/4e27cb63adb440c6825a159d35cf4010.html
[Link 5]: https://www.javanav.com/interview/03affb2ce3f04fda8853f714e5764906.html
[Link 6]: https://www.javanav.com/interview/07a32a9ff17a4006a53550ce658cafed.html
[Link 7]: https://www.javanav.com/interview/5c466456e9b54ab0a749b5948e51f1d3.html
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[Link 9]: https://www.javanav.com/interview/d3f058cfc05d4c6dadd821b622e84d36.html
[Link 10]: https://www.javanav.com/interview/67a50996c28f418e83b109ea42fc3eff.html
[Linux]: https://www.javanav.com/interview/00cccb81729540d1923bd0a0ef49533a.html
[MySQL]: https://www.javanav.com/interview/d311e78502a845f1a4bb307bd6aec2b3.html
[Oracle]: https://www.javanav.com/interview/5f29e9677edf4a16be3dce30d257c9ab.html
[Redis]: https://www.javanav.com/interview/066c62b3af4d4827b2243a822c3084a9.html
[Dubbo]: https://www.javanav.com/interview/9a3e7a7740324757abaab953f7ebc455.html