作者郵箱: [email protected]

參考+學習連結: https://blog.csdn.net/niugang0920/article/details/81100700
(對於EnableAutoConfiguration進行了深入的講解)

@EnableAutoConfiguration

簡介

@EnableAutoConfiguration是類級註釋。 這個註釋告訴Spring Boot根據你新增的jar依賴關係“猜測”你將如何配置Spring（Spring Boot自動配置嘗試根據您新增的jar依賴項自動配置Spring應用程式）。例如你在pom.xml引入了spring-boot-starter-web，Spring將自動引入新增Tomcat和Spring MVC相關jar依賴，因此自動配置將假設您正在開發Web應用程式並相應地設定了預設的Spring環境。具體請檢視

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

研究完後, 記得教教我啊, 師傅 !!!

一: 可以通過actuator進行獲取配置資訊進行監控.
二: 如果您需要了解當前正在應用的自動配置以及原因，請啟動您的應用程式使用–debug開關。 這將為選擇的核心記錄器啟用除錯日誌並記錄自動配置報告到控制檯。
可在applycation.properties中配置 debug=true
或者在jvm中新增引數 -Ddebug=true

控制檯輸出結果:

============================
CONDITIONS EVALUATION REPORT  -> 自動裝配環境報告
============================


Positive matches: (已啟用的自動裝配)
-----------------

   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: (未啟用的自動配置)
-----------------

   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: (以排除的自動配置)
-----------

    None


Unconditional classes: (無條件類)
----------------------

    org.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfiguration

    org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration

    org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration
 

禁用特定的自動配置

如果您發現正在應用您不需要的特定自動配置類，則可以使用exclude屬性@EnableAutoConfiguration來禁用它們(具體配置類, 請檢視如上的spring.factories檔案)
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 // -> 標識該類是一個類似xml的配置類
@EnableAutoConfiguration(exclude = {DataSourceAutoConfiguration.class}) //  -> 禁止資料來源自動裝配
public class BeanConfiguration {
}

如果類不在類路徑上，則可以使用excludeName註釋的屬性並指定完全限定名稱。最後，您還可以控制要通過spring.autoconfigure.exclude屬性排除的自動配置類列表 。