@EnableAutoConfiguration自动装配以及查看装配结果

参考+学习链接: https://blog.csdn.net/niugang0920/article/details/81100700
(对于EnableAutoConfiguration进行了深入的讲解)

@EnableAutoConfiguration

简介

@EnableAutoConfiguration是类级注释。这个注释告诉Spring Boot根据你添加的jar依赖关系“猜测”你将如何配置Spring（Spring Boot自动配置尝试根据您添加的jar依赖项自动配置Spring应用程序）。例如你在pom.xml引入了spring-boot-starter-web，Spring将自动引入添加Tomcat和Spring MVC相关jar依赖，因此自动配置将假设您正在开发Web应用程序并相应地设置了默认的Spring环境。具体请查看

spring-boot-autoconfigure:xxx.RELEASE.jar中的META-INF/spring.factories中的EnableAutoConfiguration配置

在这里插入图片描述

研究完后, 记得教教我啊, 师傅 !!!

一: 可以通过actuator进行获取配置信息进行监控.
二: 如果您需要了解当前正在应用的自动配置以及原因，请启动您的应用程序使用–debug开关。这将为选择的核心记录器启用调试日志并记录自动配置报告到控制台。
可在applycation.properties中配置 debug=true
或者在jvm中添加参数 -Ddebug=true

控制台输出结果:

============================
CONDITIONS EVALUATION REPORT  -> 自动装配环境报告
============================


Positive matches: (已启用的自动装配)
-----------------

   CodecsAutoConfiguration matched:
      - @ConditionalOnClass found required class 'org.springframework.http.codec.CodecConfigurer'; @ConditionalOnMissingClass did not find unwanted class (OnClassCondition)

   CodecsAutoConfiguration.JacksonCodecConfiguration matched:
      - @ConditionalOnClass found required class 'com.fasterxml.jackson.databind.ObjectMapper'; @ConditionalOnMissingClass did not find unwanted class (OnClassCondition)

   CodecsAutoConfiguration.JacksonCodecConfiguration#jacksonCodecCustomizer matched:
      - @ConditionalOnBean (types: com.fasterxml.jackson.databind.ObjectMapper; SearchStrategy: all) found bean 'jacksonObjectMapper' (OnBeanCondition)

   DispatcherServletAutoConfiguration matched:
      - @ConditionalOnClass found required class 'org.springframework.web.servlet.DispatcherServlet'; @ConditionalOnMissingClass did not find unwanted class (OnClassCondition)
      - found ConfigurableWebEnvironment (OnWebApplicationCondition)

   DispatcherServletAutoConfiguration.DispatcherServletConfiguration matched:
      - @ConditionalOnClass found required class 'javax.servlet.ServletRegistration'; @ConditionalOnMissingClass did not find unwanted class (OnClassCondition)
      - Default DispatcherServlet did not find dispatcher servlet beans (DispatcherServletAutoConfiguration.DefaultDispatcherServletCondition)

   DispatcherServletAutoConfiguration.DispatcherServletRegistrationConfiguration matched:
      - @ConditionalOnClass found required class 'javax.servlet.ServletRegistration'; @ConditionalOnMissingClass did not find unwanted class (OnClassCondition)
      - DispatcherServlet Registration did not find servlet registration bean (DispatcherServletAutoConfiguration.DispatcherServletRegistrationCondition)

Negative matches: (未启用的自动配置)
-----------------

   ActiveMQAutoConfiguration:
      Did not match:
         - @ConditionalOnClass did not find required classes 'javax.jms.ConnectionFactory', 'org.apache.activemq.ActiveMQConnectionFactory' (OnClassCondition)

   AopAutoConfiguration:
      Did not match:
         - @ConditionalOnClass did not find required classes 'org.aspectj.lang.annotation.Aspect', 'org.aspectj.lang.reflect.Advice', 'org.aspectj.weaver.AnnotatedElement' (OnClassCondition)

   ArtemisAutoConfiguration:
      Did not match:
         - @ConditionalOnClass did not find required classes 'javax.jms.ConnectionFactory', 'org.apache.activemq.artemis.jms.client.ActiveMQConnectionFactory' (OnClassCondition)

   BatchAutoConfiguration:
      Did not match:
         - @ConditionalOnClass did not find required classes 'org.springframework.batch.core.launch.JobLauncher', 'org.springframework.jdbc.core.JdbcOperations' (OnClassCondition)

Exclusions: (以排除的自动配置)
-----------

    None


Unconditional classes: (无条件类)
----------------------

    org.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfiguration

    org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration

    org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration

禁用特定的自动配置

如果您发现正在应用您不需要的特定自动配置类，则可以使用exclude属性@EnableAutoConfiguration来禁用它们(具体配置类, 请查看如上的spring.factories文件)
如下例子所示:

package com.springboot.springbootnext.configuration;

import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.boot.web.servlet.ServletComponentScan;
import org.springframework.context.annotation.Configuration;
/**
 * @describe:
 * @author: caichangmeng <[email protected]>
 * @since: 2018/10/29
 */
@Configuration // -> 标识该类是一个类似xml的配置类
@EnableAutoConfiguration(exclude = {DataSourceAutoConfiguration.class}) //  -> 禁止数据源自动装配
public class BeanConfiguration {
}

如果类不在类路径上，则可以使用excludeName注释的属性并指定完全限定名称。最后，您还可以控制要通过spring.autoconfigure.exclude属性排除的自动配置类列表。