給容器中注冊組件：

• 包掃描 + 組件標注注解(@Controller/@Service/@Repository/@Component) 有局限性，針對自己寫的類可以加這些注解，但是對于導入的第三方包，如果沒加這些注解，則無法在spring中進行bean的管理

• @Bean【導入第三方包里面的組件】

• @Import【快速給容器中導入一個組件】

  • @Import（要導入到容器的組件）；容器中就會自動注冊這個組件，id默認是全類名

  代碼：

package common.config;import common.bean.Person; import org.springframework.context.annotation.*; import testimport.Color;//配置類 == 配置文件 @Configuration //告訴sprng這是一個配置類 @Import(Color.class) public class MainConfig {//給容器注冊一個bean；類型是返回值的類型，id默認用方法名做id@Bean("peron")public Person person01() {return new Person("zhangsan", 18);} }

測試代碼：

package common;import common.config.MainConfig; import org.junit.Test; import org.springframework.context.annotation.AnnotationConfigApplicationContext;public class TestImport {AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig.class);private void printBeans(AnnotationConfigApplicationContext applicationContext) {String[] definitionNames = applicationContext.getBeanDefinitionNames();for (String name : definitionNames){System.out.println(name);}}@Testpublic void testImport(){printBeans(applicationContext);} }

輸出：

二月 27, 2019 2:25:28 下午 org.springframework.context.annotation.AnnotationConfigApplicationContext prepareRefresh 信息: Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@8807e25: startup date [Wed Feb 27 14:25:28 CST 2019]; root of context hierarchy org.springframework.context.annotation.internalConfigurationAnnotationProcessor org.springframework.context.annotation.internalAutowiredAnnotationProcessor org.springframework.context.annotation.internalRequiredAnnotationProcessor org.springframework.context.annotation.internalCommonAnnotationProcessor org.springframework.context.event.internalEventListenerProcessor org.springframework.context.event.internalEventListenerFactory mainConfig testimport.Color peron

• ImportSelector 接口，方法selectImports返回需要導入的全類名數組

package testimport;import org.springframework.context.annotation.ImportSelector; import org.springframework.core.type.AnnotationMetadata; import org.springframework.stereotype.Component;@Component public class MyImportSelector implements ImportSelector {@Overridepublic String[] selectImports(AnnotationMetadata importingClassMetadata) {return new String[]{"testimport.Red","testimport.Blue"};} } //配置類 == 配置文件 @Configuration //告訴sprng這是一個配置類 @Import({Color.class,MyImportSelector.class}) public class MainConfig {//給容器注冊一個bean；類型是返回值的類型，id默認用方法名做id@Bean("peron")public Person person01() {return new Person("zhangsan", 18);} }

測試的結果顯示如下：

org.springframework.context.annotation.internalConfigurationAnnotationProcessor org.springframework.context.annotation.internalAutowiredAnnotationProcessor org.springframework.context.annotation.internalRequiredAnnotationProcessor org.springframework.context.annotation.internalCommonAnnotationProcessor org.springframework.context.event.internalEventListenerProcessor org.springframework.context.event.internalEventListenerFactory mainConfig testimport.Color testimport.Red testimport.Blue peron

接口ImportSelector的方法selectImports返回的組件的全類名已經全部注入到組件

• ImportBeanDefinitionRegistrar.registerBeanDefinitions注冊組件 手動注冊bean

package testimport;import org.springframework.beans.factory.support.BeanDefinitionRegistry; import org.springframework.beans.factory.support.RootBeanDefinition; import org.springframework.context.annotation.ImportBeanDefinitionRegistrar; import org.springframework.core.type.AnnotationMetadata;public class MyImportBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar {@Overridepublic void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {boolean definition = registry.containsBeanDefinition("testimport.Blue");boolean red = registry.containsBeanDefinition("testimport.Red");if (definition && red){RootBeanDefinition beanDefinition = new RootBeanDefinition(RainBow.class);registry.registerBeanDefinition("rainbow",beanDefinition);}} } @Configuration //告訴sprng這是一個配置類 @Import({Color.class,MyImportSelector.class,MyImportBeanDefinitionRegistrar.class}) public class MainConfig {//給容器注冊一個bean；類型是返回值的類型，id默認用方法名做id@Bean("peron")public Person person01() {return new Person("zhangsan", 18);} }

測試輸出：

org.springframework.context.annotation.internalConfigurationAnnotationProcessor org.springframework.context.annotation.internalAutowiredAnnotationProcessor org.springframework.context.annotation.internalRequiredAnnotationProcessor org.springframework.context.annotation.internalCommonAnnotationProcessor org.springframework.context.event.internalEventListenerProcessor org.springframework.context.event.internalEventListenerFactory mainConfig testimport.Color testimport.Red testimport.Blue peron rainbow

import注冊組件的方式比較重要，做個記錄

轉載于:https://my.oschina.net/wuyiyi/blog/3015510

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