目录
抛出问题
@SpringBootApplication
public class LearnspringbootApplication {
public static void main(String[] args) {
SpringApplication.run(LearnspringbootApplication.class, args);
}
}
大家可以看到，如上所示是一个很常见的SpringBoot启动类，我们可以看到仅仅使用了一个Main方法就启动了整个SpringBoot项目是不是很神奇，下面我们来仔细剖析以下这一段代码，这段代码中我们可以仔细地观察到最重要的两个部分，分别是@SpringBootApplication注解和SpringApplication这个类。
- @SpringBootApplication注解
- SpringApplication类
@SpringBootApplication注解剖析
打开这个@SpringBootApplication注解，如下所示
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = {
@Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
public @interface SpringBootApplication {
@AliasFor(annotation = EnableAutoConfiguration.class)
Class<?>[] exclude() default {};
@AliasFor(annotation = EnableAutoConfiguration.class)
String[] excludeName() default {};
@AliasFor(annotation = ComponentScan.class, attribute = "basePackages")
String[] scanBasePackages() default {};
@AliasFor(annotation = ComponentScan.class, attribute = "basePackageClasses")
Class<?>[] scanBasePackageClasses() default {};
}
我们可以发现；我们可以在@SpringBootApplication注解中使用exclude(),excludeName(),scanBasePackages(),scanBasePackageClasses() 这四个方法来进行自定义我们需要排除装配的Bean，扫描包路径，扫描类路径。
搭眼一瞅，在@SpringBootApplication注解上还有下面那么多注解。
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = {
@Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
这四个注解不用看，就是关于注解的一些定义
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootConfiguration注解我们点进去看一下，发现是下面这个样子，@SpringBootConfiguration注解上又标注了@Configuration注解，想必在@Configuration注解上也标注了@Component注解，这不就是我们上一章节说的Spring的模式注解。总的来说嘛，SpringBootConfiguration注解的作用就是把类变成可以被Spring管理的Bean
结论 １ ：也就是说标注
@SpringBootApplication注解的类会成为Spring的Bean
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Configuration
public @interface SpringBootConfiguration {
}
我们再来看一下@EnableAutoConfiguration，从名字上我们就可以看到“启用自动装配”的意思。那我们可要仔细看一下。从下面我们可以看到只有两个我们需要了解的注解，分别是＠AutoConfigurationPackage和＠Import注解。
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@AutoConfigurationPackage
@Import(AutoConfigurationImportSelector.class)
public @interface EnableAutoConfiguration {
String ENABLED_OVERRIDE_PROPERTY = "spring.boot.enableautoconfiguration";
Class<?>[] exclude() default {};
String[] excludeName() default {};
}
当我点进去＠AutoConfigurationPackage注解中，发现该注解又启用了一个模块装配@Import(AutoConfigurationPackages.Registrar.class)（上一章节有讲到）；所以又点进去AutoConfigurationPackages.Registrar.class这个类，发现这个类又实现了两个接口ImportBeanDefinitionRegistrar和DeterminableImports 在该类的实现方法中的PackageImport()；最后终于发现了下面这段代码。
PackageImport(AnnotationMetadata metadata) {
this.packageName = ClassUtils.getPackageName(metadata.getClassName());
}
结论 2 :SpringBoot默认会装配启动类路径的所有包下可装配的Bean；也就是说如果你把SpringBoot启动类放在一个单独的包中，则SpringBoot不会装配到你的其他Bean。这时候你就要使用
@SpringBootApplication的scanBasePackages()方法进行另行配置。
此时@EnableAutoConfiguration注解仅仅就剩下@Import(AutoConfigurationImportSelector.class)没有看了，不过从注解上我们可以看到使用@Import注解，所以可以知道SpringBoot使用的是模块装配的接口实现方式。所以我么针对AutoConfigurationImportSelector这个类仔细剖析一下。AutoConfigurationImportSelector - > AutoConfigurationImportSelector.selectImports() ->getAutoConfigurationEntry() -> getCandidateConfigurations() ->SpringFactoriesLoader.loadFactoryNames() -> loadFactoryNames() ->loadSpringFactories() ; 哈哈果然源码不经扒；看下面源码；META-INF/spring.factories这不就是配置SpringBoot自动配置的文件嘛。
public static final String FACTORIES_RESOURCE_LOCATION = "META-INF/spring.factories";
Enumeration<URL> urls = (classLoader != null ?
classLoader.getResources(FACTORIES_RESOURCE_LOCATION) :
ClassLoader.getSystemResources(FACTORIES_RESOURCE_LOCATION));
结论 3 ：SpringBoot在启动时会自动加载Classpth路径下的
META-INF/spring.factories文件，所以我们可以将需要自动配置的Bean写入这个文件，SPringBoot会替我们自动装配。这也正是配置SpringBoot自动配置的步骤。
SpringApplication类剖析
@SpringBootApplication
public class LearnspringbootApplication {
public static void main(String[] args) {
SpringApplication.run(LearnspringbootApplication.class, args);
}
}
在Main方法中我们可以看到SpringApplication作为一个启动类来启动SpringBoot应用程序。那么SpringApplication类是如何进行启动整个应用程序的呢？
第一步：配置SpringBoot Bean来源
public SpringApplication(Class<?>... primarySources) {
this(null, primarySources);
}
从SpringApplication类的构造方法中我们可以看到，这里传入了一个主Bean来源；因为我们将标注了@SpringBootApplication注解的LearnspringbootApplication.class传递了进来，所以@SpringBootApplication扫描到的Bean和自动装配的Bean会作为主Bean来源。当然我们可以调用该类的setSources()方法设置自己的SpringXML配置。
第二步 ：自动推断SpringBoot的应用类型
this.webApplicationType = WebApplicationType.deduceFromClasspath();
从上面一句代码（既SpringApplication初始化方法中一行代码）；我们观察deduceFromClasspath()方法可以看到，SpringBoot判断类路径下是否存在下面类进而判断SpringBoot的应用类型。三种类型分别是NONE，SERVLET，REACTIVE 。当然我们也可以调用setWebApplicationType()自行设置。
private static final String[] SERVLET_INDICATOR_CLASSES = { "javax.servlet.Servlet",
"org.springframework.web.context.ConfigurableWebApplicationContext" };
private static final String WEBMVC_INDICATOR_CLASS = "org.springframework."
+ "web.servlet.DispatcherServlet";
private static final String WEBFLUX_INDICATOR_CLASS = "org."
+ "springframework.web.reactive.DispatcherHandler";
private static final String JERSEY_INDICATOR_CLASS = "org.glassfish.jersey.servlet.ServletContainer";
private static final String SERVLET_APPLICATION_CONTEXT_CLASS = "org.springframework.web.context.WebApplicationContext";
private static final String REACTIVE_APPLICATION_CONTEXT_CLASS = "org.springframework.boot.web.reactive.context.ReactiveWebApplicationContext";
第三步：推断SpringBoot的引导类
this.mainApplicationClass = deduceMainApplicationClass();
从上面一句代码（既SpringApplication初始化方法中一行代码）；我们可以通过deduceMainApplicationClass()方法可以看到SpringBoot根据Main 线程执行堆栈判断实际的引导类。（PS:存在一种情况就是标注@SpringBootApplication注解的并不是引导类情况）
private Class<?> deduceMainApplicationClass() {
try {
StackTraceElement[] stackTrace = new RuntimeException().getStackTrace();
for (StackTraceElement stackTraceElement : stackTrace) {
if ("main".equals(stackTraceElement.getMethodName())) {
return Class.forName(stackTraceElement.getClassName());
}
}
}
catch (ClassNotFoundException ex) {
// Swallow and continue
}
return null;
}
第四步：加载应用上下文初始化器
setInitializers((Collection) getSpringFactoriesInstances(
ApplicationContextInitializer.class));
从上面一句代码（既SpringApplication初始化方法中一行代码）；我们发现setInitializers()方法会调用getSpringFactoriesInstances() -> getSpringFactoriesInstances（） -> getSpringFactoriesInstances() 该方法会使用SpringFactoriesLoader类记进行加载配置资源既META-INF/spring.factories，利用 Spring 工厂加载机制,实例化 ApplicationContextInitializer 实现类,并排序对象集合。并使用AnnotationAwareOrderComparator类的sort（）方法进行排序。
private <T> Collection<T> getSpringFactoriesInstances(Class<T> type,
Class<?>[] parameterTypes, Object... args) {
ClassLoader classLoader = getClassLoader();
// Use names and ensure unique to protect against duplicates
Set<String> names = new LinkedHashSet<>(
SpringFactoriesLoader.loadFactoryNames(type, classLoader));
List<T> instances = createSpringFactoriesInstances(type, parameterTypes,
classLoader, args, names);
AnnotationAwareOrderComparator.sort(instances);
return instances;
}
第五步 ：加载应用事件监听器
setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
从上面一句代码（既SpringApplication初始化方法中一行代码）；从setListeners() 方法中可以看到该方法仍然调用getSpringFactoriesInstances()方法，不同的是利用 Spring 工厂加载META-INF/spring.factories,实例化 ApplicationListener 实现类,并排序对象集合
第六步：启动SpringApplication 运行监听器( SpringApplicationRunListeners )
从SpringApplication类的run()方法中，我们可以看到下面代码getRunListeners()方法同样利用 Spring 工厂加载机制,读取 SpringApplicationRunListener 对象集合,并且封装到组合类
SpringApplicationRunListeners对象中并启动运行监听器。
SpringApplicationRunListeners listeners = getRunListeners(args);
listeners.starting();
第七步：监听SpringBoot/Spring事件
Spring Boot 通过 SpringApplicationRunListener 的实现类 EventPublishingRunListener 利用 Spring Framework 事件
API ,广播 Spring Boot 事件。
第八步：创建SpringBoot的应用上下文
context = createApplicationContext();
从SpringApplication类的run()方法中,我们可看到createApplicationContext()根据第二步推断的SpringBoot应用类型创建相应的上下文。
protected ConfigurableApplicationContext createApplicationContext() {
Class<?> contextClass = this.applicationContextClass;
if (contextClass == null) {
try {
switch (this.webApplicationType) {
case SERVLET:
contextClass = Class.forName(DEFAULT_SERVLET_WEB_CONTEXT_CLASS);
break;
case REACTIVE:
contextClass = Class.forName(DEFAULT_REACTIVE_WEB_CONTEXT_CLASS);
break;
default:
contextClass = Class.forName(DEFAULT_CONTEXT_CLASS);
}
}
catch (ClassNotFoundException ex) {
throw new IllegalStateException(
"Unable create a default ApplicationContext, "
+ "please specify an ApplicationContextClass",
ex);
}
}
return (ConfigurableApplicationContext) BeanUtils.instantiateClass(contextClass);
}
根据推断的SpringBoot应用类型创建下面三种之一的上下文
public static final String DEFAULT_CONTEXT_CLASS = "org.springframework.context."
+ "annotation.AnnotationConfigApplicationContext";
public static final String DEFAULT_SERVLET_WEB_CONTEXT_CLASS = "org.springframework.boot."
+ "web.servlet.context.AnnotationConfigServletWebServerApplicationContext";
public static final String DEFAULT_REACTIVE_WEB_CONTEXT_CLASS = "org.springframework."
+ "boot.web.reactive.context.AnnotationConfigReactiveWebServerApplicationContext";
第九步：创建 Environment
ConfigurableEnvironment environment = prepareEnvironment(listeners,
applicationArguments);
configureIgnoreBeanInfo(environment);
从SpringApplication类的run()方法中,我们可看到prepareEnvironment()根据第二步推断的SpringBoot应用类型创建相应的上下文。创建不同的Environment 。从下面可以看到他们分别是StandardServletEnvironment，StandardReactiveWebEnvironment，StandardEnvironment
private ConfigurableEnvironment getOrCreateEnvironment() {
if (this.environment != null) {
return this.environment;
}
switch (this.webApplicationType) {
case SERVLET:
return new StandardServletEnvironment();
case REACTIVE:
return new StandardReactiveWebEnvironment();
default:
return new StandardEnvironment();
}
}
结论
-
标注
@SpringBootApplication注解的类会成为Spring的Bean -
SpringBoot默认会装配启动类路径的所有包下可装配的Bean；也就是说如果你把SpringBoot启动类放在一个单独的包中，则SpringBoot不会装配到你的其他Bean。这时候你就要使用
@SpringBootApplication的scanBasePackages()方法进行另行配置。 -
SpringBoot在启动时会自动加载Classpth路径下的
META-INF/spring.factories文件，所以我们可以将需要自动配置的Bean写入这个文件。同样SpringBoot也会扫描Jar包中的META-INF/spring.factories文件；例如当导入spring-boot-starter起步依赖的时候，并且启用了自动装配注解@EnableAutoConfiguration，就将会替我们自动装配如如下类；如果满足条件的话。org.springframework.boot.autoconfigure.EnableAutoConfiguration= org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration, org.springframework.boot.autoconfigure.aop.AopAutoConfiguration, org.springframework.boot.autoconfigure.amqp.RabbitAutoConfiguration, org.springframework.boot.autoconfigure.batch.BatchAutoConfiguration, org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration, org.springframework.boot.autoconfigure.cassandra.CassandraAutoConfiguration, org.springframework.boot.autoconfigure.cloud.CloudServiceConnectorsAutoConfiguration, org.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfiguration, org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration, org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration, org.springframework.boot.autoconfigure.couchbase.CouchbaseAutoConfiguration, org.springframework.boot.autoconfigure.dao.PersistenceExceptionTranslationAutoConfiguration, org.springframework.boot.autoconfigure.data.cassandra.CassandraDataAutoConfiguration, org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveDataAutoConfiguration, org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.data.cassandra.CassandraRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.data.couchbase.CouchbaseDataAutoConfiguration, org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveDataAutoConfiguration, org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.data.couchbase.CouchbaseRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchAutoConfiguration, org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchDataAutoConfiguration, org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.data.jdbc.JdbcRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.data.ldap.LdapRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.data.mongo.MongoDataAutoConfiguration, org.springframework.boot.autoconfigure.data.mongo.MongoReactiveDataAutoConfiguration, org.springframework.boot.autoconfigure.data.mongo.MongoReactiveRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.data.mongo.MongoRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.data.neo4j.Neo4jDataAutoConfiguration, org.springframework.boot.autoconfigure.data.neo4j.Neo4jRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.data.solr.SolrRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration, org.springframework.boot.autoconfigure.data.redis.RedisReactiveAutoConfiguration, org.springframework.boot.autoconfigure.data.redis.RedisRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.data.rest.RepositoryRestMvcAutoConfiguration, org.springframework.boot.autoconfigure.data.web.SpringDataWebAutoConfiguration, org.springframework.boot.autoconfigure.elasticsearch.jest.JestAutoConfiguration, org.springframework.boot.autoconfigure.elasticsearch.rest.RestClientAutoConfiguration, org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration, org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration, org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration, org.springframework.boot.autoconfigure.h2.H2ConsoleAutoConfiguration, org.springframework.boot.autoconfigure.hateoas.HypermediaAutoConfiguration, org.springframework.boot.autoconfigure.hazelcast.HazelcastAutoConfiguration, org.springframework.boot.autoconfigure.hazelcast.HazelcastJpaDependencyAutoConfiguration, org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration, org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration, org.springframework.boot.autoconfigure.influx.InfluxDbAutoConfiguration, org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration, org.springframework.boot.autoconfigure.integration.IntegrationAutoConfiguration, org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.JndiDataSourceAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.XADataSourceAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration, org.springframework.boot.autoconfigure.jms.JmsAutoConfiguration, org.springframework.boot.autoconfigure.jmx.JmxAutoConfiguration, org.springframework.boot.autoconfigure.jms.JndiConnectionFactoryAutoConfiguration, org.springframework.boot.autoconfigure.jms.activemq.ActiveMQAutoConfiguration, org.springframework.boot.autoconfigure.jms.artemis.ArtemisAutoConfiguration, org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAutoConfiguration, org.springframework.boot.autoconfigure.jersey.JerseyAutoConfiguration, org.springframework.boot.autoconfigure.jooq.JooqAutoConfiguration, org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration, org.springframework.boot.autoconfigure.kafka.KafkaAutoConfiguration, org.springframework.boot.autoconfigure.ldap.embedded.EmbeddedLdapAutoConfiguration, org.springframework.boot.autoconfigure.ldap.LdapAutoConfiguration, org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration, org.springframework.boot.autoconfigure.mail.MailSenderAutoConfiguration, org.springframework.boot.autoconfigure.mail.MailSenderValidatorAutoConfiguration, org.springframework.boot.autoconfigure.mongo.embedded.EmbeddedMongoAutoConfiguration, org.springframework.boot.autoconfigure.mongo.MongoAutoConfiguration, org.springframework.boot.autoconfigure.mongo.MongoReactiveAutoConfiguration, org.springframework.boot.autoconfigure.mustache.MustacheAutoConfiguration, org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration, org.springframework.boot.autoconfigure.quartz.QuartzAutoConfiguration, org.springframework.boot.autoconfigure.reactor.core.ReactorCoreAutoConfiguration, org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration, org.springframework.boot.autoconfigure.security.servlet.SecurityRequestMatcherProviderAutoConfiguration, org.springframework.boot.autoconfigure.security.servlet.UserDetailsServiceAutoConfiguration, org.springframework.boot.autoconfigure.security.servlet.SecurityFilterAutoConfiguration, org.springframework.boot.autoconfigure.security.reactive.ReactiveSecurityAutoConfiguration, org.springframework.boot.autoconfigure.security.reactive.ReactiveUserDetailsServiceAutoConfiguration, org.springframework.boot.autoconfigure.sendgrid.SendGridAutoConfiguration, org.springframework.boot.autoconfigure.session.SessionAutoConfiguration, org.springframework.boot.autoconfigure.security.oauth2.client.servlet.OAuth2ClientAutoConfiguration, org.springframework.boot.autoconfigure.security.oauth2.client.reactive.ReactiveOAuth2ClientAutoConfiguration, org.springframework.boot.autoconfigure.security.oauth2.resource.servlet.OAuth2ResourceServerAutoConfiguration, org.springframework.boot.autoconfigure.security.oauth2.resource.reactive.ReactiveOAuth2ResourceServerAutoConfiguration, org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration, org.springframework.boot.autoconfigure.task.TaskExecutionAutoConfiguration, org.springframework.boot.autoconfigure.task.TaskSchedulingAutoConfiguration, org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration, org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration, org.springframework.boot.autoconfigure.transaction.jta.JtaAutoConfiguration, org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration, org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration, org.springframework.boot.autoconfigure.web.embedded.EmbeddedWebServerFactoryCustomizerAutoConfiguration, org.springframework.boot.autoconfigure.web.reactive.HttpHandlerAutoConfiguration, org.springframework.boot.autoconfigure.web.reactive.ReactiveWebServerFactoryAutoConfiguration, org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration, org.springframework.boot.autoconfigure.web.reactive.error.ErrorWebFluxAutoConfiguration, org.springframework.boot.autoconfigure.web.reactive.function.client.ClientHttpConnectorAutoConfiguration, org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration, org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration, org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfiguration, org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration, org.springframework.boot.autoconfigure.web.servlet.HttpEncodingAutoConfiguration, org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration, org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration, org.springframework.boot.autoconfigure.websocket.reactive.WebSocketReactiveAutoConfiguration, org.springframework.boot.autoconfigure.websocket.servlet.WebSocketServletAutoConfiguration, org.springframework.boot.autoconfigure.websocket.servlet.WebSocketMessagingAutoConfiguration, org.springframework.boot.autoconfigure.webservices.WebServicesAutoConfiguration, org.springframework.boot.autoconfigure.webservices.client.WebServiceTemplateAutoConfiguration
该教程所属Java工程师之SpringBoot系列教程，本系列相关博文目录 Java工程师之SpringBoot系列教程前言&目录