12.26 查看Spring Boot在启动的时候注入了哪些bean？

Spring Boot启动的时候需要自动加载许多Bean实现最小化配置，下面我们通过代码输出Spring启动后加载的所有Bean信息。

在Spring boot应用入口，添加如下代码：

<code>@SpringBootApplication
public class SpringbootFirstApplication {
    public static void main(String[] args) {
        SpringApplication.run(SpringbootFirstApplication.class, args);
    }

    @Bean
    public CommandLineRunner commandLineRunner(ApplicationContext ctx) {
        return args -> {
            System.out.println("Let's inspect the beans provided by Spring Boot:");
            String[] beanNames = ctx.getBeanDefinitionNames();
            Arrays.sort(beanNames);
            for (String beanName : beanNames) {
                System.out.println(beanName);
            }
        };
    }
}/<code>

CommandLineRunner方法标记为@Bean，在启动spring boot应用的时候会运行。它检索应用程序创建的所有bean，或者由spring boot自动添加的bean。接着排序，并打印输出。

查看输出结果，spring boot 会自动注入beans如下：

<code>Let's inspect the beans provided by Spring Boot:
application
beanNameHandlerMapping
defaultServletHandlerMapping
dispatcherServlet
embeddedServletContainerCustomizerBeanPostProcessor
handlerExceptionResolver
helloController
httpRequestHandlerAdapter
messageSource
mvcContentNegotiationManager
mvcConversionService
mvcValidator
org.springframework.boot.autoconfigure.MessageSourceAutoConfiguration
org.springframework.boot.autoconfigure.PropertyPlaceholderAutoConfiguration
org.springframework.boot.autoconfigure.web.EmbeddedServletContainerAutoConfiguration
org.springframework.boot.autoconfigure.web.EmbeddedServletContainerAutoConfiguration$DispatcherServletConfiguration
org.springframework.boot.autoconfigure.web.EmbeddedServletContainerAutoConfiguration$EmbeddedTomcat
org.springframework.boot.autoconfigure.web.ServerPropertiesAutoConfiguration
org.springframework.boot.context.embedded.properties.ServerProperties
org.springframework.context.annotation.ConfigurationClassPostProcessor.enhancedConfigurationProcessor
org.springframework.context.annotation.ConfigurationClassPostProcessor.importAwareProcessor
org.springframework.context.annotation.internalAutowiredAnnotationProcessor
org.springframework.context.annotation.internalCommonAnnotationProcessor
org.springframework.context.annotation.internalConfigurationAnnotationProcessor
org.springframework.context.annotation.internalRequiredAnnotationProcessor
org.springframework.web.servlet.config.annotation.DelegatingWebMvcConfiguration
propertySourcesBinder
propertySourcesPlaceholderConfigurer
requestMappingHandlerAdapter
requestMappingHandlerMapping
resourceHandlerMapping
simpleControllerHandlerAdapter
tomcatEmbeddedServletContainerFactory
viewControllerHandlerMapping/<code>

另外一个方法是通过在spring boot应用的pom.xml中添加Actuator依赖包：

<dependency>

<groupid>org.springframework.boot/<groupid>

<artifactid>spring-boot-starter-actuator/<artifactid>

同时在application.properties 配置文件中开启Actuator端口：

management.endpoints.web.exposure.include=*

然后启动spring boot应用，访问/beans 端点也可以获取到bean列表。

http://localhost:8080/actuator/beans

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關鍵字: annotation 哪些 Spring