SpringBoot 2.0 系列004 --启动实战之配置文件

àì夳堔傛蜴生んèń 2022-05-23 22:37 196阅读 0赞

# SpringBoot 2.0 系列004 --启动实战之配置文件 #

## 配置文件 ##

### 配置文件加载流程 ###

> 很多文档包括官方文档说SB的默认配置文件是application开头的文件，那么是为什么呢？

*  我们先看下流程图 [![SpringBoot_execute_application.png][]][SpringBoot_execute_application.png]

> 由上述流程我们发现，在执行SpringApplication的run方法中的prepareEnvironment子方法时，触发ConfigFileApplicationListener类中的 load方法，完成配置文件的加载

*  ConfigFileApplicationListener分析

public void load() { 
      this.profiles = Collections.asLifoQueue(new LinkedList<Profile>());
      this.processedProfiles = new LinkedList<>();
      this.activatedProfiles = false;
      this.loaded = new LinkedHashMap<>();
      // 核心初始化方法 负责初始化 profile （spring.profiles.active） 
      // 如果没有则使用默认的AbstractEnvironment类中的(spring.profiles.default)default(可以是application-default名称的，也可以起不加)
      initializeProfiles();
      // 不为空时 循环加载 初始化了 理论上不会为空
      while (!this.profiles.isEmpty()) { 
        Profile profile = this.profiles.poll();
        // 第二步 此方法加载 文件的前缀 active 以及后缀 和路径 
        load(profile, this::getPositiveProfileFilter,
             addToLoaded(MutablePropertySources::addLast, false));
        this.processedProfiles.add(profile);
      }
      // 默认加载的
      load(null, this::getNegativeProfileFilter,
           addToLoaded(MutablePropertySources::addFirst, true));
      addLoadedPropertySources();

*  接 上边标注第二步的位置

private void load(Profile profile, DocumentFilterFactory filterFactory,
    				DocumentConsumer consumer) {
         
                // getSearch 如果你配置了spring.config.location 路径 则使用此处路径
                // 否则是用默认的 ConfigFileApplicationListener.DEFAULT_SEARCH_LOCATIONS
                // 即 private static final String DEFAULT_SEARCH_LOCATIONS = "classpath:/,classpath:/config/,file:./,file:./config/";
    			getSearchLocations().forEach((location) -> {
         
    				boolean isFolder = location.endsWith("/");
    				// getSearchNames 是你配置文件的名称 ，如果配置了spring.config.name 则使用配置的这个名字
    				// 否则使用默认的 private static final String DEFAULT_NAMES = "application";
    				// 这就是默认是application这个名字的原因
    				Set<String> names = (isFolder ? getSearchNames() : NO_SEARCH_NAMES);
    				names.forEach(
    				       
                            // 第三步 location是路径 name是文件名 profile则是-defalut部分或者其他-dev之类的
    						(name) -> load(location, name, profile, filterFactory, consumer));
    			});
    		}

*  接上边标注第三步

private void load(String location, String name, Profile profile,
    				DocumentFilterFactory filterFactory, DocumentConsumer consumer) {
         
        
                // 这里需要注意的是propertySourceLoaders 此处是在new loader的时候初始化的,即我们流程中的addPropertySources一步
                   				        //底层使用的是META-INF/spring.factories
                   				        /** org.springframework.boot.env.PropertySourceLoader=\
                                              org.springframework.boot.env.PropertiesPropertySourceLoader,\
                                              org.springframework.boot.env.YamlPropertySourceLoader
                                           */
               // 这也就是 文件后缀支持 yml，yaml,properties,xml的原因
               // 没有名字的情况
    			if (!StringUtils.hasText(name)) {
         
    				for (PropertySourceLoader loader : this.propertySourceLoaders) {
         
    					if (canLoadFileExtension(loader, location)) {
         
    						load(loader, location, profile,
    								filterFactory.getDocumentFilter(profile), consumer);
    					}
    				}
    			}
    			// 带后缀名的情况
    			for (PropertySourceLoader loader : this.propertySourceLoaders) {
         
    				for (String fileExtension : loader.getFileExtensions()) {
         
    					String prefix = location + name;
    					fileExtension = "." + fileExtension;
    					// 第四步 通过后缀名方式加载
    					loadForFileExtension(loader, prefix, fileExtension, profile,
    							filterFactory, consumer);
    				}
    			}
    		}

*  接第四步

private void loadForFileExtension(PropertySourceLoader loader, String prefix,
    				String fileExtension, Profile profile,
    				DocumentFilterFactory filterFactory, DocumentConsumer consumer) {
         
    			DocumentFilter defaultFilter = filterFactory.getDocumentFilter(null);
    			DocumentFilter profileFilter = filterFactory.getDocumentFilter(profile);
    			// 前边说的 -default和-dev部分
    			if (profile != null) {
         
    				// Try profile-specific file & profile section in profile file (gh-340)
    				// prefix 是路径名+文件名
    				// fileExtension是.yml这种
    				// profile 则是第一步initializeProfiles 是this.profiles注入的
    				String profileSpecificFile = prefix + "-" + profile + fileExtension;
    				// 各处执行装载 扫描不同路径下是否有对应配置文件
    				load(loader, profileSpecificFile, profile, defaultFilter, consumer);
    				load(loader, profileSpecificFile, profile, profileFilter, consumer);
    				// Try profile specific sections in files we've already processed
    				for (Profile processedProfile : this.processedProfiles) {
         
    					if (processedProfile != null) {
         
    						String previouslyLoaded = prefix + "-" + processedProfile
    								+ fileExtension;
    						load(loader, previouslyLoaded, profile, profileFilter, consumer);
    					}
    				}
    			}
    			// Also try the profile-specific section (if any) of the normal file
    			 各处执行装载 扫描不同路径下是否有对应配置文件
    			// 第五步
    			load(loader, prefix + fileExtension, profile, profileFilter, consumer);
    		}

*  接 第五步

> 第三步和第四步都会执行下面的方法

private void load(PropertySourceLoader loader, String location, Profile profile,
    				DocumentFilter filter, DocumentConsumer consumer) {
         
    			try {
         
    				Resource resource = this.resourceLoader.getResource(location);
    				String description = getDescription(location, resource);
    				if (profile != null) {
         
    					description = description + " for profile " + profile;
    				}
    				if (resource == null || !resource.exists()) {
         
    					this.logger.trace("Skipped missing config " + description);
    					return;
    				}
    				if (!StringUtils.hasText(
    						StringUtils.getFilenameExtension(resource.getFilename()))) {
         
    					this.logger.trace("Skipped empty config extension " + description);
    					return;
    				}
    				String name = "applicationConfig: [" + location + "]";
    				// 转换成docment对象 
    				List<Document> documents = loadDocuments(loader, name, resource);
    				if (CollectionUtils.isEmpty(documents)) {
         
    					this.logger.trace("Skipped unloaded config " + description);
    					return;
    				}
    				List<Document> loaded = new ArrayList<>();
    				for (Document document : documents) {
         
    				    // 文档Filter
    					if (filter.match(document)) {
         
    						maybeActivateProfiles(document.getActiveProfiles());
    						addProfiles(document.getIncludeProfiles());
    						loaded.add(document);
    					}
    				}
    				Collections.reverse(loaded);
    				if (!loaded.isEmpty()) {
         
    				    // consumer对象来自 addToLoaded方法 目的是装载到PropertySources中
    					loaded.forEach((document) -> consumer.accept(profile, document));
    					
    					// 开启debug后 打印出这句话 表示文件被加载完毕。 
    					this.logger.debug("Loaded config file " + description);
    				}
    			}
    			catch (Exception ex) {
         
    				throw new IllegalStateException("Failed to load property "
    						+ "source from location '" + location + "'", ex);
    			}
    		}

### 配置文件使用 ###

> 由上述分析可知，默认的配置文件名为application(-\{profile\}).yml/xml/yaml/properties，且默认支持项目的resources路径

#### 问题1 怎么使用名称不是application的文件？ ####

> 根据流程分析可知，文件默认完整名称是由spring.config.name和spring.profiles.default两条属性控制。由此可知，在启动前注入此属性即可。

*  目标 ，修改默认application为ricky01 ,defalut默认bgt01
 *  在resources新建如下几个文件及内容

> 默认端口是8010 其他是8011，8012，8013，

[![cp04_configname.png][]][cp04_configname.png]

*  注入 spring.config.name和spring.profiles.default属性

> 主要有如下3种方式

/**
         *   测试自定义加载文件的方式 01  通过启动设置参数
         *  --spring.config.name=ricky01 --spring.profiles.default=bgt01
         * @param args
         */
        public static void main01(String[] args) throws InterruptedException {
         
            SpringApplication application = new SpringApplication(SpringBootApplication01.class);
            application.run(args);
        }
    
        /**
         *   测试自定义加载文件的方式 01  通过启动设置参数
         *  设置环境变量
         * @param args
         */
        public static void main02(String[] args) throws InterruptedException {
         
            System.setProperty("spring.config.name", "ricky01");
            System.setProperty("spring.profiles.default", "bgt02");
            SpringApplication application = new SpringApplication(SpringBootApplication01.class);
            application.run(args);
        }
    
        /**
         *   测试自定义加载文件的方式 01  通过启动设置参数
         *  设置传入参数
         * @param args
         */
        public static void main(String[] args) throws InterruptedException {
         
            args=new String[2];
            args[0]="--spring.config.name=ricky01";
            args[1]="--spring.profiles.default=bgt03";
            SpringApplication application = new SpringApplication(SpringBootApplication01.class);
            application.run(args);
        }

*  结果

> 公用ricky01.yml中的contextpath，服务端口却是各自定义的。以下是bgt03时的启动日志

.   ____          _            __ _ _
     /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
    ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
     \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
      '  |____| .__|_| |_|_| |_\__, | / / / /
     =========|_|==============|___/=/_/_/_/
     :: Spring Boot ::        (v2.0.1.RELEASE)
    
    2018-05-16 13:40:25.165  INFO 24984 --- [           main] com.ricky.SpringBootApplication01        : Starting SpringBootApplication01 on jsb-bgt with PID 24984 (D:\work\ideawork\SpringBootLearn\chapter04\target\classes started by zdwljs in D:\work\ideawork\SpringBootLearn)
    2018-05-16 13:40:25.169  INFO 24984 --- [           main] com.ricky.SpringBootApplication01        : No active profile set, falling back to default profiles: bgt03
    2018-05-16 13:40:25.263  INFO 24984 --- [           main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@3e92efc3: startup date [Wed May 16 13:40:25 CST 2018]; root of context hierarchy
    2018-05-16 13:40:28.721  INFO 24984 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8013 (http)
    2018-05-16 13:40:28.756  INFO 24984 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
    2018-05-16 13:40:28.757  INFO 24984 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.29
    2018-05-16 13:40:28.770  INFO 24984 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener   : The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [D:\Program Files\Java\jdk1.8.0_161\bin;C:\WINDOWS\Sun\Java\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common;d:\work\Git\cmd;C:\Program Files (x86)\MySQL\MySQL Server 5.5\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;C:\Users\zdwljs\AppData\Local\Microsoft\WindowsApps;D:\Program Files\Java\jdk1.8.0_161\bin;;.]
    2018-05-16 13:40:28.924  INFO 24984 --- [ost-startStop-1] o.a.c.c.C.[.[localhost].[/ricky01]       : Initializing Spring embedded WebApplicationContext
    2018-05-16 13:40:28.924  INFO 24984 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 3672 ms
    2018-05-16 13:40:29.149  INFO 24984 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Servlet dispatcherServlet mapped to [/]
    2018-05-16 13:40:29.155  INFO 24984 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
    2018-05-16 13:40:29.155  INFO 24984 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
    2018-05-16 13:40:29.155  INFO 24984 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
    2018-05-16 13:40:29.155  INFO 24984 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
    2018-05-16 13:40:29.371  INFO 24984 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
    2018-05-16 13:40:29.783  INFO 24984 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@3e92efc3: startup date [Wed May 16 13:40:25 CST 2018]; root of context hierarchy
    2018-05-16 13:40:29.905  INFO 24984 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{ [/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
    2018-05-16 13:40:29.907  INFO 24984 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{ [/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
    2018-05-16 13:40:29.947  INFO 24984 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
    2018-05-16 13:40:29.947  INFO 24984 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
    2018-05-16 13:40:30.183  INFO 24984 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
    2018-05-16 13:40:30.245  INFO 24984 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8013 (http) with context path '/ricky01'
    2018-05-16 13:40:30.251  INFO 24984 --- [           main] com.ricky.SpringBootApplication01        : Started SpringBootApplication01 in 5.845 seconds (JVM running for 6.639)

#### 问题2 怎么使用外部配置文件加载 方便统一管理 ####

> 比如我们放在D:\\work\\ricky\\config目录下管理

*  目标 使用d盘config目录下的文件，如下

[![cp04_configout01.png][]][cp04_configout01.png]

*  第一步 在d盘新建上述文件 默认端口是8020 bgt01端口则是8021
 *  第二步 更改加载路径，如下

> 这里 只罗列一种方式 其他的和上面修改apllication方式一样

public static void main(String[] args) throws InterruptedException {
         
            args=new String[3];
            args[0]="--spring.config.location=file:d:/work/ricky/config/";
            args[1]="--spring.config.name=ricky02";
            args[2]="--spring.profiles.default=bgt01";
            SpringApplication application = new SpringApplication(SpringBootApplication02.class);
            application.run(args);
        }

*  结果

.   ____          _            __ _ _
     /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
    ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
     \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
      '  |____| .__|_| |_|_| |_\__, | / / / /
     =========|_|==============|___/=/_/_/_/
     :: Spring Boot ::        (v2.0.1.RELEASE)
    
    2018-05-16 14:09:21.111  INFO 19708 --- [           main] com.ricky.SpringBootApplication02        : Starting SpringBootApplication02 on jsb-bgt with PID 19708 (D:\work\ideawork\SpringBootLearn\chapter04\target\classes started by zdwljs in D:\work\ideawork\SpringBootLearn)
    2018-05-16 14:09:21.118  INFO 19708 --- [           main] com.ricky.SpringBootApplication02        : No active profile set, falling back to default profiles: bgt01
    2018-05-16 14:09:21.221  INFO 19708 --- [           main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@1ab06251: startup date [Wed May 16 14:09:21 CST 2018]; root of context hierarchy
    2018-05-16 14:09:24.122  INFO 19708 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8021 (http)
    2018-05-16 14:09:24.187  INFO 19708 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
    2018-05-16 14:09:24.187  INFO 19708 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.29
    2018-05-16 14:09:24.208  INFO 19708 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener   : The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [D:\Program Files\Java\jdk1.8.0_161\bin;C:\WINDOWS\Sun\Java\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common;d:\work\Git\cmd;C:\Program Files (x86)\MySQL\MySQL Server 5.5\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;C:\Users\zdwljs\AppData\Local\Microsoft\WindowsApps;D:\Program Files\Java\jdk1.8.0_161\bin;;.]
    2018-05-16 14:09:24.427  INFO 19708 --- [ost-startStop-1] o.a.c.c.C.[.[localhost].[/ricky02]       : Initializing Spring embedded WebApplicationContext
    2018-05-16 14:09:24.429  INFO 19708 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 3225 ms
    2018-05-16 14:09:24.748  INFO 19708 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Servlet dispatcherServlet mapped to [/]
    2018-05-16 14:09:24.756  INFO 19708 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
    2018-05-16 14:09:24.757  INFO 19708 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
    2018-05-16 14:09:24.757  INFO 19708 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
    2018-05-16 14:09:24.758  INFO 19708 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
    2018-05-16 14:09:24.980  INFO 19708 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
    2018-05-16 14:09:25.424  INFO 19708 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@1ab06251: startup date [Wed May 16 14:09:21 CST 2018]; root of context hierarchy
    2018-05-16 14:09:25.583  INFO 19708 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{ [/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
    2018-05-16 14:09:25.586  INFO 19708 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{ [/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
    2018-05-16 14:09:25.672  INFO 19708 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
    2018-05-16 14:09:25.672  INFO 19708 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
    2018-05-16 14:09:25.989  INFO 19708 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
    2018-05-16 14:09:26.185  INFO 19708 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8021 (http) with context path '/ricky02'
    2018-05-16 14:09:26.191  INFO 19708 --- [           main] com.ricky.SpringBootApplication02        : Started SpringBootApplication02 in 13.196 seconds (JVM running for 14.36)

> 这里实现的只是外部的，如果你还是需要在项目中则可以修改location=classpath:/XXX/

## 演示项目地址,欢迎fork和star ##

> 码云：[SpringBootLearn][]

# 最后 #

*  [SpringBoot 2.0 系列001 -- 入门介绍以及相关概念][SpringBoot 2.0 _001 --]
 *  [SpringBoot 2.0 系列002 --运行流程分析][SpringBoot 2.0 _002 --]
 *  [SpringBoot 2.0 系列003 -- 自定义Parent][SpringBoot 2.0 _003 -- _Parent]
 *  作者ricky
 *  交流群：244930845

[SpringBoot_execute_application.png]: /images/20220524/c2cb23783322434ca6784e60f9d93209.png
[cp04_configname.png]: /images/20220524/fc897ded57a84a0aa50fdb6837f25223.png
[cp04_configout01.png]: /images/20220524/844c580bfd344e8ab3f5afbac682801f.png
[SpringBootLearn]: https://gitee.com/bgt0314/SpringBootLearn
[SpringBoot 2.0 _001 --]: https://blog.csdn.net/u014042066/article/details/80271073
[SpringBoot 2.0 _002 --]: https://blog.csdn.net/u014042066/article/details/80311954
[SpringBoot 2.0 _003 -- _Parent]: https://blog.csdn.net/u014042066/article/details/80321856