前言

Spring Boot启动的时候需要加载许多Bean实现最小化配置，本文将尝试找出Spring启动后加载的所有Bean信息；

通过ApplicationContext 去获取所有的Bean

通过CommandLineRunner接口，可以实现在Spring Boot完全启动后执行一些代码逻辑，本文将执行的逻辑是打印所有Bean的信息；

1. 通过 ApplicationContext.getBeanDefinitionNames() 方法获取所有Bean的名称；
2. 通过 ApplicationContext.getBean(beanName) 获取Bean的详细信息；

具体代码实现如下：

package com.howtodoinjava.app.controller;

import java.util.Arrays;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.boot.CommandLineRunner;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.boot.builder.SpringApplicationBuilder;

import org.springframework.boot.web.support.SpringBootServletInitializer;

import org.springframework.context.ApplicationContext;

@SpringBootApplication

public class SpringBootWebApplication extends SpringBootServletInitializer implements CommandLineRunner {

    @Override

    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {

        return application.sources(SpringBootWebApplication.class);

    }

    public static void main(String[] args) throws Exception {

        SpringApplication.run(SpringBootWebApplication.class, args);

    }

    @Autowired

    private ApplicationContext appContext;

    @Override

    public void run(String... args) throws Exception

    {

        String[] beans = appContext.getBeanDefinitionNames();

        Arrays.sort(beans);

        for (String bean : beans)

        {

            System.out.println(bean + " of Type :: " + appContext.getBean(bean).getClass());

        }

    }

}

运行以上程序，控制台将打印如下信息：

2017-03-06 13:22:50 - Tomcat started on port(s): 8080 (http)

basicErrorController of Type :: class org.springframework.boot.autoconfigure.web.BasicErrorController

beanNameHandlerMapping of Type :: class org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping

beanNameViewResolver of Type :: class org.springframework.web.servlet.view.BeanNameViewResolver

characterEncodingFilter of Type :: class org.springframework.boot.web.filter.OrderedCharacterEncodingFilter

conventionErrorViewResolver of Type :: class org.springframework.boot.autoconfigure.web.DefaultErrorViewResolver

defaultServletHandlerMapping of Type :: class org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport$EmptyHandlerMapping

defaultViewResolver of Type :: class org.springframework.web.servlet.view.InternalResourceViewResolver

dispatcherServlet of Type :: class org.springframework.web.servlet.DispatcherServlet

dispatcherServletRegistration of Type :: class org.springframework.boot.web.servlet.ServletRegistrationBean

duplicateServerPropertiesDetector of Type :: class org.springframework.boot.autoconfigure.web.ServerPropertiesAutoConfiguration$DuplicateServerPropertiesDetector

embeddedServletContainerCustomizerBeanPostProcessor of Type :: class org.springframework.boot.context.embedded.EmbeddedServletContainerCustomizerBeanPostProcessor

error of Type :: class org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration$SpelView

errorAttributes of Type :: class org.springframework.boot.autoconfigure.web.DefaultErrorAttributes

...

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