SpringBoot 2.0 系列002 --运行流程分析

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发布时间：2019-06-29

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SpringBoot 2.0 系列002 --运行流程分析

1. SpringBoot运行的几种方式

1.1 开发环境，右键配置类main方法运行

配置如下，引入相关pom依赖，运行main方法即可启动简单的SpringBoot web应用。

//开启SpringBoot自动注入配置  等价于原来的SpringBootApplication@EnableAutoConfiguration//开启RestController注解  含有ResponseBody 即非页面形式@RestControllerpublic class SpringBootApplication {    @GetMapping("/")    public String home() {        return "Hello World!";    }    /**     * 开启SpringBoot服务     * @param args     */    public static void main(String[] args) {        //等价于 new SpringApplication(SpringBootApplication.class).run(args);        SpringApplication.run(SpringBootApplication.class,args);    }}

1.2 jar文件运行

其他部分与上述相同，需要注意的是pom文件需要加入


                
                     
      
       org.springframework.boot
                      
      
       spring-boot-maven-plugin

打包方式选择为jar

jar

最后mvn package打包，idea里面如下

运行方式1，如下

运行方式2，如下

D:\work\ideawork\SpringBootLearn\chapter02\target>java -jar chapter02-2.0.1.RELEASE.jar  .   ____          _            __ _ _ /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ \\/  ___)| |_)| | | | | || (_| |  ) ) ) )  '  |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot ::        (v2.0.1.RELEASE)2018-05-11 09:42:52.870  INFO 9720 --- [           main] com.ricky.SpringBootApplication          : Starting SpringBootApplication v2.0.1.RELEASE on jsb-bgt with PID 9720 (D:\work\ideawork\SpringBootLearn\chapter02\target\chapter02-2.0.1.RELEASE.jar started by zdwljs in D:\work\ideawork\SpringBootLearn\chapter02\target)2018-05-11 09:42:52.877  INFO 9720 --- [           main] com.ricky.SpringBootApplication          : No active profile set, falling back to default profiles: default2018-05-11 09:42:52.979  INFO 9720 --- [           main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@5f8ed237: startup date [Fri May 11 09:42:52 CST 2018]; root of context hierarchy2018-05-11 09:42:55.596  INFO 9720 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)2018-05-11 09:43:01.810  INFO 9720 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]2018-05-11 09:43:01.811  INFO 9720 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.292018-05-11 09:43:01.827  INFO 9720 --- [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;;.]2018-05-11 09:43:01.988  INFO 9720 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext2018-05-11 09:43:01.991  INFO 9720 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 9018 ms2018-05-11 09:43:02.238  INFO 9720 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Servlet dispatcherServlet mapped to [/]2018-05-11 09:43:02.263  INFO 9720 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]2018-05-11 09:43:02.264  INFO 9720 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]2018-05-11 09:43:02.267  INFO 9720 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]2018-05-11 09:43:02.271  INFO 9720 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]2018-05-11 09:43:02.437  INFO 9720 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2018-05-11 09:43:02.877  INFO 9720 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@5f8ed237: startup date [Fri May 11 09:42:52 CST 2018]; root of context hierarchy2018-05-11 09:43:03.069  INFO 9720 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/],methods=[GET]}" onto public java.lang.String com.ricky.SpringBootApplication.home()2018-05-11 09:43:03.079  INFO 9720 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity
    
     
      > org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.error(javax.servlet.http.HttpServletRequest)2018-05-11 09:43:03.083  INFO 9720 --- [           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)2018-05-11 09:43:03.139  INFO 9720 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2018-05-11 09:43:03.140  INFO 9720 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2018-05-11 09:43:03.386  INFO 9720 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup2018-05-11 09:43:03.457  INFO 9720 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''2018-05-11 09:43:03.466  INFO 9720 --- [           main] com.ricky.SpringBootApplication          : Started SpringBootApplication in 11.232 seconds (JVM running for 11.882)

通过ctrl-c可以退出

1.3 war包方式

1.3.1 war形式基本是使用外部tomcat，则需要将内置tomcat依赖过滤掉，且需要添加开发servlet依赖。


                
     
      org.springframework.boot
                 
     
      spring-boot-starter-web
                 
                     
                      
                          
       
        org.springframework.boot
                           
       
        spring-boot-starter-tomcat
                       
                  
             
            
            
            
            
                
     
      javax.servlet
                 
     
      javax.servlet-api
                 
     
      3.1.0
                 
     
      provided

1.3.2 注意将打包方式改为war形式

war

1.3.3 两种加载方式

需要配置启动类，如下

继承SpringBootServletInitializer，重写configure方法。

//开启SpringBoot自动注入配置  等价于原来的SpringBootApplication@EnableAutoConfiguration//开启RestController注解  含有ResponseBody 即非页面形式@RestControllerpublic class SpringBootApplicationServletInitializer extends SpringBootServletInitializer{    @GetMapping("/")    public String home(HttpServletRequest request) {        return "Hello World!";    }    @Override    protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) {        return builder.sources(SpringBootApplicationServletInitializer.class);    }   }

另一种则是不需要继承SpringBootServletInitializer。保持与jar文件方式一致即可。虽然也可以正常访问。但是application.yml中的配置不生效。需要通过其他方式进行参数配置。

1.3.3 打包运行

1、 mvn package打包,生成chapter02-2.0.1.RELEASE.war 文件。

3、启动tomcat。(注意：测试发现是没有spring的日志，但是访问正常)

11-May-2018 11:53:34.687 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Server version:        Apache Tomcat/8.5.2911-May-2018 11:53:34.694 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Server built:          Mar 5 2018 13:11:12 UTC11-May-2018 11:53:34.697 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Server number:         8.5.29.011-May-2018 11:53:34.698 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log OS Name:               Windows 1011-May-2018 11:53:34.698 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log OS Version:            10.011-May-2018 11:53:34.698 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Architecture:          amd6411-May-2018 11:53:34.699 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Java Home:             D:\Program Files\Java\jdk1.8.0_161\jre11-May-2018 11:53:34.703 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log JVM Version:           1.8.0_161-b1211-May-2018 11:53:34.704 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log JVM Vendor:            Oracle Corporation11-May-2018 11:53:34.706 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log CATALINA_BASE:         D:\work\apache-tomcat-8.5.2911-May-2018 11:53:34.708 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log CATALINA_HOME:         D:\work\apache-tomcat-8.5.2911-May-2018 11:53:34.708 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.util.logging.config.file=D:\work\apache-tomcat-8.5.29\conf\logging.properties11-May-2018 11:53:34.709 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager11-May-2018 11:53:34.710 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djdk.tls.ephemeralDHKeySize=204811-May-2018 11:53:34.714 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.protocol.handler.pkgs=org.apache.catalina.webresources11-May-2018 11:53:34.718 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dignore.endorsed.dirs=11-May-2018 11:53:34.723 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcatalina.base=D:\work\apache-tomcat-8.5.2911-May-2018 11:53:34.725 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcatalina.home=D:\work\apache-tomcat-8.5.2911-May-2018 11:53:34.731 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.io.tmpdir=D:\work\apache-tomcat-8.5.29\temp11-May-2018 11:53:34.739 信息 [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent Loaded APR based Apache Tomcat Native library [1.2.16] using APR version [1.6.3].11-May-2018 11:53:34.740 信息 [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent APR capabilities: IPv6 [true], sendfile [true], accept filters [false], random [true].11-May-2018 11:53:34.741 信息 [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent APR/OpenSSL configuration: useAprConnector [false], useOpenSSL [true]11-May-2018 11:53:35.865 信息 [main] org.apache.catalina.core.AprLifecycleListener.initializeSSL OpenSSL successfully initialized [OpenSSL 1.0.2m  2 Nov 2017]11-May-2018 11:53:36.129 信息 [main] org.apache.coyote.AbstractProtocol.init Initializing ProtocolHandler ["http-nio-8080"]11-May-2018 11:53:36.509 信息 [main] org.apache.tomcat.util.net.NioSelectorPool.getSharedSelector Using a shared selector for servlet write/read11-May-2018 11:53:36.519 信息 [main] org.apache.coyote.AbstractProtocol.init Initializing ProtocolHandler ["ajp-nio-8009"]11-May-2018 11:53:36.532 信息 [main] org.apache.tomcat.util.net.NioSelectorPool.getSharedSelector Using a shared selector for servlet write/read11-May-2018 11:53:36.533 信息 [main] org.apache.catalina.startup.Catalina.load Initialization processed in 2548 ms11-May-2018 11:53:36.584 信息 [main] org.apache.catalina.core.StandardService.startInternal Starting service [Catalina]11-May-2018 11:53:36.584 信息 [main] org.apache.catalina.core.StandardEngine.startInternal Starting Servlet Engine: Apache Tomcat/8.5.2911-May-2018 11:53:36.629 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployWAR Deploying web application archive [D:\work\apache-tomcat-8.5.29\webapps\chapter02-2.0.1.RELEASE.war]11-May-2018 11:53:40.555 信息 [localhost-startStop-1] org.apache.jasper.servlet.TldScanner.scanJars At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.11-May-2018 11:53:41.025 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployWAR Deployment of web application archive [D:\work\apache-tomcat-8.5.29\webapps\chapter02-2.0.1.RELEASE.war] has finished in [4,393] ms11-May-2018 11:53:41.148 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory [D:\work\apache-tomcat-8.5.29\webapps\docs]11-May-2018 11:53:41.258 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [D:\work\apache-tomcat-8.5.29\webapps\docs] has finished in [119] ms11-May-2018 11:53:41.266 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory [D:\work\apache-tomcat-8.5.29\webapps\examples]11-May-2018 11:53:41.987 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [D:\work\apache-tomcat-8.5.29\webapps\examples] has finished in [721] ms11-May-2018 11:53:42.048 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory [D:\work\apache-tomcat-8.5.29\webapps\host-manager]11-May-2018 11:53:42.114 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [D:\work\apache-tomcat-8.5.29\webapps\host-manager] has finished in [66] ms11-May-2018 11:53:42.116 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory [D:\work\apache-tomcat-8.5.29\webapps\manager]11-May-2018 11:53:42.175 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [D:\work\apache-tomcat-8.5.29\webapps\manager] has finished in [59] ms11-May-2018 11:53:42.176 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory [D:\work\apache-tomcat-8.5.29\webapps\ROOT]11-May-2018 11:53:42.240 信息 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [D:\work\apache-tomcat-8.5.29\webapps\ROOT] has finished in [64] ms11-May-2018 11:53:42.254 信息 [main] org.apache.coyote.AbstractProtocol.start Starting ProtocolHandler ["http-nio-8080"]11-May-2018 11:53:42.274 信息 [main] org.apache.coyote.AbstractProtocol.start Starting ProtocolHandler ["ajp-nio-8009"]11-May-2018 11:53:42.284 信息 [main] org.apache.catalina.startup.Catalina.start Server startup in 5749 ms

查看tomcat的App服务

4、点击chapter02-2.0.1.RELEASE访问我们部署的项目。

2. SpringBoot是怎么运行起来的？

我们以jar文件方式为例进行讲解。

2.1 jar文件目录结构

D:\work\xxxxx\SpringBootLearn\chapter02\target>jar tf chapter02-2.0.1.RELEASE.jarMETA-INF/META-INF/MANIFEST.MForg/org/springframework/org/springframework/boot/org/springframework/boot/loader/org/springframework/boot/loader/util/org/springframework/boot/loader/util/SystemPropertyUtils.classorg/springframework/boot/loader/PropertiesLauncher$1.classorg/springframework/boot/loader/PropertiesLauncher$PrefixMatchingArchiveFilter.classorg/springframework/boot/loader/Launcher.classorg/springframework/boot/loader/PropertiesLauncher$ArchiveEntryFilter.classorg/springframework/boot/loader/PropertiesLauncher.classorg/springframework/boot/loader/jar/org/springframework/boot/loader/jar/JarURLConnection.classorg/springframework/boot/loader/jar/JarURLConnection$1.classorg/springframework/boot/loader/jar/Bytes.classorg/springframework/boot/loader/jar/JarURLConnection$JarEntryName.classorg/springframework/boot/loader/jar/JarFileEntries$1.classorg/springframework/boot/loader/jar/JarEntry.classorg/springframework/boot/loader/jar/JarFileEntries.classorg/springframework/boot/loader/jar/JarEntryFilter.classorg/springframework/boot/loader/jar/ZipInflaterInputStream.classorg/springframework/boot/loader/jar/StringSequence.classorg/springframework/boot/loader/jar/JarFile$1.classorg/springframework/boot/loader/ExecutableArchiveLauncher.classorg/springframework/boot/loader/archive/org/springframework/boot/loader/archive/JarFileArchive$JarFileEntry.classorg/springframework/boot/loader/archive/ExplodedArchive$FileEntryIterator.classorg/springframework/boot/loader/archive/ExplodedArchive$FileEntry.classorg/springframework/boot/loader/archive/ExplodedArchive.classorg/springframework/boot/loader/archive/ExplodedArchive$1.classorg/springframework/boot/loader/archive/JarFileArchive$EntryIterator.classorg/springframework/boot/loader/archive/Archive$Entry.classorg/springframework/boot/loader/archive/Archive.classorg/springframework/boot/loader/archive/Archive$EntryFilter.classorg/springframework/boot/loader/archive/ExplodedArchive$FileEntryIterator$EntryComparator.classorg/springframework/boot/loader/archive/JarFileArchive.classorg/springframework/boot/loader/data/org/springframework/boot/loader/data/RandomAccessDataFile$FileAccess.classorg/springframework/boot/loader/data/RandomAccessDataFile$DataInputStream.classorg/springframework/boot/loader/JarLauncher.classorg/springframework/boot/loader/jar/JarFile.classorg/springframework/boot/loader/jar/CentralDirectoryParser.classorg/springframework/boot/loader/jar/AsciiBytes.classorg/springframework/boot/loader/jar/FileHeader.classorg/springframework/boot/loader/jar/JarFile$JarFileType.classorg/springframework/boot/loader/jar/Handler.classorg/springframework/boot/loader/jar/JarFileEntries$EntryIterator.classorg/springframework/boot/loader/jar/CentralDirectoryVisitor.classorg/springframework/boot/loader/jar/CentralDirectoryEndRecord.classorg/springframework/boot/loader/jar/CentralDirectoryFileHeader.classorg/springframework/boot/loader/jar/JarFile$2.classorg/springframework/boot/loader/LaunchedURLClassLoader.classorg/springframework/boot/loader/MainMethodRunner.classorg/springframework/boot/loader/data/RandomAccessDataFile.classorg/springframework/boot/loader/WarLauncher.classorg/springframework/boot/loader/data/RandomAccessDataFile$1.classorg/springframework/boot/loader/data/RandomAccessData.classorg/springframework/boot/loader/LaunchedURLClassLoader$UseFastConnectionExceptionsEnumeration.classBOOT-INF/BOOT-INF/classes/BOOT-INF/classes/com/BOOT-INF/classes/com/ricky/META-INF/maven/META-INF/maven/chapter02/META-INF/maven/chapter02/chapter02/BOOT-INF/classes/com/ricky/SpringBootApplication.classMETA-INF/maven/chapter02/chapter02/pom.propertiesMETA-INF/maven/chapter02/chapter02/pom.xmlBOOT-INF/lib/BOOT-INF/lib/spring-boot-starter-web-2.0.1.RELEASE.jarBOOT-INF/lib/spring-boot-starter-2.0.1.RELEASE.jarBOOT-INF/lib/spring-boot-2.0.1.RELEASE.jarBOOT-INF/lib/spring-boot-autoconfigure-2.0.1.RELEASE.jarBOOT-INF/lib/spring-boot-starter-logging-2.0.1.RELEASE.jarBOOT-INF/lib/logback-classic-1.2.3.jarBOOT-INF/lib/logback-core-1.2.3.jarBOOT-INF/lib/slf4j-api-1.7.25.jarBOOT-INF/lib/log4j-to-slf4j-2.10.0.jarBOOT-INF/lib/log4j-api-2.10.0.jarBOOT-INF/lib/jul-to-slf4j-1.7.25.jarBOOT-INF/lib/javax.annotation-api-1.3.2.jarBOOT-INF/lib/spring-core-5.0.5.RELEASE.jarBOOT-INF/lib/spring-jcl-5.0.5.RELEASE.jarBOOT-INF/lib/snakeyaml-1.19.jarBOOT-INF/lib/spring-boot-starter-json-2.0.1.RELEASE.jarBOOT-INF/lib/jackson-databind-2.9.5.jarBOOT-INF/lib/jackson-annotations-2.9.0.jarBOOT-INF/lib/jackson-core-2.9.5.jarBOOT-INF/lib/jackson-datatype-jdk8-2.9.5.jarBOOT-INF/lib/jackson-datatype-jsr310-2.9.5.jarBOOT-INF/lib/jackson-module-parameter-names-2.9.5.jarBOOT-INF/lib/spring-boot-starter-tomcat-2.0.1.RELEASE.jarBOOT-INF/lib/tomcat-embed-core-8.5.29.jarBOOT-INF/lib/tomcat-embed-el-8.5.29.jarBOOT-INF/lib/tomcat-embed-websocket-8.5.29.jarBOOT-INF/lib/hibernate-validator-6.0.9.Final.jarBOOT-INF/lib/validation-api-2.0.1.Final.jarBOOT-INF/lib/jboss-logging-3.3.2.Final.jarBOOT-INF/lib/classmate-1.3.4.jarBOOT-INF/lib/spring-web-5.0.5.RELEASE.jarBOOT-INF/lib/spring-beans-5.0.5.RELEASE.jarBOOT-INF/lib/spring-webmvc-5.0.5.RELEASE.jarBOOT-INF/lib/spring-aop-5.0.5.RELEASE.jarBOOT-INF/lib/spring-context-5.0.5.RELEASE.jarBOOT-INF/lib/spring-expression-5.0.5.RELEASE.jar

打开MANIFEST.MF文件

Manifest-Version: 1.0Implementation-Title: chapter01 Maven WebappImplementation-Version: 2.0.1.RELEASEBuilt-By: zdwljsImplementation-Vendor-Id: chapter02Spring-Boot-Version: 2.0.1.RELEASEMain-Class: org.springframework.boot.loader.JarLauncherStart-Class: com.ricky.SpringBootApplicationSpring-Boot-Classes: BOOT-INF/classes/Spring-Boot-Lib: BOOT-INF/lib/Created-By: Apache Maven 3.3.9Build-Jdk: 1.8.0_161Implementation-URL: http://www.example.com

Start-class是我们的SpringBootApplication类，即jar文件方式启动跟开发环境右键main方法运行方式一致

Main-Class则是JarLauncher。如果打包方式是war的话则是WarLauncher。此类工作内容是讲字节码文件加载到jvm中。

2.2 SpringBoot执行

由上述分析可知，com.ricky.SpringBootApplication是我们加载SB的入口。

入口

SpringApplication 的静态run方法。也可以手动new SpringApplication

SpringApplication.run(SpringBootApplication.class,args);

入口调用链1

/**    * 调用run方法  返回ConfigurableApplicationContext对象 此对象用法在03章节做讲解    */ 	public static ConfigurableApplicationContext run(Class
       primarySource, 			String... args) { 		return run(new Class
      [] { primarySource }, args); 	}

入口调用链1

/**        *  此处有两步处理        *   1. 创建SpringApplication 对象        *   2. 执行该对象的run方法        */ 		public static ConfigurableApplicationContext run(Class
      [] primarySources,    			String[] args) {    		return new SpringApplication(primarySources).run(args);    	}

创建SpringApplication 对象的过程

第一步调用构造方法

//调用构造方法	public SpringApplication(Class
        ... primarySources) {		this(null, primarySources);	}

第2步调用构造方法

//调用构造方法	public SpringApplication(Class
        ... primarySources) {		this(null, primarySources);	}

第3步具体构造方法解析

//调用构造方法	public SpringApplication(ResourceLoader resourceLoader, Class
        ... primarySources) {	        //默认resourceLoader 为null    		this.resourceLoader = resourceLoader;	        //校验primarySources不为空    		Assert.notNull(primarySources, "PrimarySources must not be null");	        //赋值primarySources集合对象  说明此处是可以传递多个.class对象 当我们的启动类不在同一级包中           // com.ricky/ricky02  我们的启动类在ricky中，默认是只扫描ricky包中的类，如果想扫描ricky02中 可以将需要扫描的类放到此处。    		this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources));    		//加载webApplicationType 对象 推断是web环境 还是非web环境	        this.webApplicationType = deduceWebApplicationType();           //设置实例为ApplicationContextInitializer的Spring工厂实例           //可以通过spring.factories文件注入 继承自ApplicationContextInitializer的类           //也可以调用addInitializer方法手动注入    		setInitializers((Collection) getSpringFactoriesInstances(    				ApplicationContextInitializer.class));	        //注入ApplicationListener实例的监听  实现方式类似上边  通过文件或者add方法都可以    		setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));	        // 通过堆栈里获取的方式，判断main函数，找到原始启动的main函数    		this.mainApplicationClass = deduceMainApplicationClass();    	}

第4步 run方法说明

//执行run方法 返回ConfigurableApplicationContext 对象public ConfigurableApplicationContext run(String... args) {          //开启执行时间记录器		StopWatch stopWatch = new StopWatch();		stopWatch.start();          //定义context		ConfigurableApplicationContext context = null;          //定义exceptionReporters		Collection
        
          exceptionReporters = new ArrayList<>();          //设置java.awt.headless模式 主要是在缺少显示设备和键盘鼠标等下的支持  设置系统变量为true		configureHeadlessProperty();          //根据传递的参数 加载spirng.factories中的SpringApplicationRunListener实例监听对象		SpringApplicationRunListeners listeners = getRunListeners(args);          //启动监听		listeners.starting();		try {              // 将传入的参数转换为ApplicationArguments格式			ApplicationArguments applicationArguments = new DefaultApplicationArguments(					args);              // 根据applicationArguments准备基础环境变量 监听listeners变量 绑定到Spring中              //如果webApplicationType是0则做下转换处理  最后 attach做些检查判断处理			ConfigurableEnvironment environment = prepareEnvironment(listeners,					applicationArguments);	         // 从环境变量中检查和设置spring.beaninfo.ignore的状态 true或false			configureIgnoreBeanInfo(environment);	         // 从环境变量中检查和设置banner.mode的模式  OFF时不打印              // 这部分是sb项目启动时显示几行springboot字符串头像              //自定义配置可参阅 SpringApplicationBannerPrinter			Banner printedBanner = printBanner(environment);	         //创建应用上下文环境 检查是web环境还是默认环境等生成相对应环境			context = createApplicationContext();	         // 从spring.factories中获取SpringBootExceptionReporter类型的实例 			exceptionReporters = getSpringFactoriesInstances(					SpringBootExceptionReporter.class,					new Class[] { ConfigurableApplicationContext.class }, context);	         //准备context               // 参阅第五步			prepareContext(context, environment, listeners, applicationArguments,					printedBanner);	         //刷新上下文context  注意根据ServletWeb和ReactiveWeb以及默认的applicationContext的不同来进行具体刷新			refreshContext(context);	         // 刷新后的操作  现在是保留方法			afterRefresh(context, applicationArguments);	          //结束执行时间记录器			stopWatch.stop();	         // 是否开启启动日志			if (this.logStartupInfo) {				new StartupInfoLogger(this.mainApplicationClass)						.logStarted(getApplicationLog(), stopWatch);			}	         // 发布事件  context.publishEvent(ApplicationStartedEvent)			listeners.started(context);	         // 将ApplicationRunner和CommandLineRunner类型的回调处理			callRunners(context, applicationArguments);		}		catch (Throwable ex) {			handleRunFailure(context, ex, exceptionReporters, listeners);			throw new IllegalStateException(ex);		}		try {	         // context.publishEvent(ApplicationReadyEvent) 发布监听			listeners.running(context);		}		catch (Throwable ex) {			handleRunFailure(context, ex, exceptionReporters, null);			throw new IllegalStateException(ex);		}		return context;	}

第5步准备context

private void prepareContext(ConfigurableApplicationContext context,			ConfigurableEnvironment environment, SpringApplicationRunListeners listeners,			ApplicationArguments applicationArguments, Banner printedBanner) {       // 设置context环境变量		context.setEnvironment(environment);       // 注册internalConfigurationBeanNameGenerator实例  setResourceLoader 或者setClassLoader		postProcessApplicationContext(context);        // 执行ApplicationContextInitializer.initialize方法		applyInitializers(context);        // 设置监听上下文		listeners.contextPrepared(context);        // 如果启动日志开的话 则启动日志实例		if (this.logStartupInfo) {			logStartupInfo(context.getParent() == null);			logStartupProfileInfo(context);		}		// Add boot specific singleton beans        // 通过bean工厂注册springApplicationArguments的单例对象		context.getBeanFactory().registerSingleton("springApplicationArguments",				applicationArguments);        // 如果 printedBanner 不为空则通过bean工厂注册springBootBanner的单例对象		if (printedBanner != null) {			context.getBeanFactory().registerSingleton("springBootBanner", printedBanner);		}		// Load the sources  加载sources		Set

2.3 总结

通过分析，我们发现sb在启动的时候会校验执行环境(web或者其他)，根据args传入参数的不同执行不同逻辑，同时扫描的方式有包类型、resource、注解、xml等(load方法装载bean实例)。还可以根据spring.factories注入listener 、Initializers、event等等对象。