Spring注解05|Spring注解05 @Import 给容器快速导入一个组件 Spring注解05@Import给容器快速导

给容器中注册组件：一、包扫描+组件标注注解（@Controller/@Service/@Repository/@Component）[自己写的类] 二、@Bean[导入的第三方包里面的组件] 三、*@Import[快速给容器中导入一个组件] 1）、@Import(要导入到容器中的组件)；容器中就会自动注册这个组件，id默认是全类名 2）、ImportSelector:返回需要导入的组件的全类名数组； 3）、ImportBeanDefinitionRegistrar:手动注册bean到容器中四、**使用Spring提供的 FactoryBean（工厂Bean）; 1）、默认获取到的是工厂bean调用getObject创建的对象 2）、要获取工厂Bean本身，我们需要给id前面加一个&&colorFactoryBean 配置类 MainConfigImport .java

@Configuration @ComponentScan(value = "https://www.it610.com/article/com.tommy", useDefaultFilters = false) @Import({MyImportSelector.class, MyImportBeanDefinitionRegistrar.class, Yellow.class}) public class MainConfigImport { //设置FacotryBean,只能通过这个方式注入，其他的方式会有问题 @Bean public MyBlackFactoryBean myBlackFactoryBean(){ returnnew MyBlackFactoryBean(); } }

MyImportSelector.java

public class MyImportSelector implements ImportSelector { @Override public String[] selectImports(AnnotationMetadata importingClassMetadata) { return new String[]{"com.tommy.bean.Tomcat", "com.tommy.bean.Tomdog"}; } }

MyImportBeanDefinitionRegistrar.java

public class MyImportBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar { @Override public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) { final boolean b = registry.containsBeanDefinition("com.tommy.bean.Blue"); final boolean b2 = registry.containsBeanDefinition("com.tommy.bean.Tomcat"); if (!b && b2) { final BeanDefinition beanDefinition = new AnnotatedGenericBeanDefinition(Blue.class); registry.registerBeanDefinition("blue", beanDefinition); } } }

MyBlackFactoryBean.java

public class MyBlackFactoryBean implements FactoryBean { @Override public Black getObject() throws Exception { System.out.println("MyBlackFactoryBean start new Black() "); return new Black(); } @Override public Class getObjectType() { return Black.class; } @Override public boolean isSingleton() { return true; } }

【Spring注解05|Spring注解05 @Import 给容器快速导入一个组件】测试类

public class IOCTestImport { @Test public void testImport() { ApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfigImport.class); printDefindName(applicationContext); final Object blackFactoryBean = applicationContext.getBean("myBlackFactoryBean"); System.out.println("blackFactoryBean class: " + blackFactoryBean.getClass()); final Object blackFactoryBean2 = applicationContext.getBean("myBlackFactoryBean"); System.out.println("blackFactoryBean == blackFactoryBean2: " + (blackFactoryBean == blackFactoryBean2)); final Object bean3 = applicationContext.getBean("myBlackFactoryBean"); System.out.println("bean3: "+bean3.getClass()); } private void printDefindName(ApplicationContext applicationContext) { final String[] beanDefinitionNames = applicationContext.getBeanDefinitionNames(); for (String name : beanDefinitionNames) { System.out.println(name); } } }

测试结果：

org.springframework.context.annotation.internalConfigurationAnnotationProcessor org.springframework.context.annotation.internalAutowiredAnnotationProcessor org.springframework.context.annotation.internalCommonAnnotationProcessor org.springframework.context.event.internalEventListenerProcessor org.springframework.context.event.internalEventListenerFactory mainConfigImport com.tommy.bean.Tomcat com.tommy.bean.Tomdog com.tommy.bean.Yellow myBlackFactoryBean blue MyBlackFactoryBean start new Black() blackFactoryBean class: class com.tommy.bean.Black blackFactoryBean == blackFactoryBean2: true bean3: class com.tommy.bean.BlackProcess finished with exit code 0