SpringBoot 2.0 系列002 --运行流程分析

小咪咪 2022-05-25 11:57 115阅读 0赞

# 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
    @RestController
    public 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

<plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>

> 打包方式选择为jar

> 最后mvn package打包 ，idea里面如下

[![cp02_run01.png][]][cp02_run01.png]

> 运行方式1，如下

[![cp02_run02.png][]][cp02_run02.png]

> 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: default
    2018-05-11 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 hierarchy
    2018-05-11 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/8.5.29
    2018-05-11 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 WebApplicationContext
    2018-05-11 09:43:01.991  INFO 9720 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 9018 ms
    2018-05-11 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 hierarchy
    2018-05-11 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<java.util.Map<java.lang.String, java.lang.Object>> 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 startup
    2018-05-11 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。 ####

<dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
                <exclusions>
                    
                    <exclusion>
                        <groupId>org.springframework.boot</groupId>
                        <artifactId>spring-boot-starter-tomcat</artifactId>
                    </exclusion>
                </exclusions>
            </dependency>
            
            
            
            <dependency>
                <groupId>javax.servlet</groupId>
                <artifactId>javax.servlet-api</artifactId>
                <version>3.1.0</version>
                <scope>provided</scope>
            </dependency>

#### 1.3.2 注意将打包方式改为war形式 ####

#### 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
    @RestController
    public 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。
 *  2、将war文件放到webapp目录下 [![cp02_run_tomcat.png][]][cp02_run_tomcat.png]
 *  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/8.5.29
    11-May-2018 11:53:34.694 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Server built:          Mar 5 2018 13:11:12 UTC
    11-May-2018 11:53:34.697 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Server number:         8.5.29.0
    11-May-2018 11:53:34.698 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log OS Name:               Windows 10
    11-May-2018 11:53:34.698 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log OS Version:            10.0
    11-May-2018 11:53:34.698 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Architecture:          amd64
    11-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\jre
    11-May-2018 11:53:34.703 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log JVM Version:           1.8.0_161-b12
    11-May-2018 11:53:34.704 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log JVM Vendor:            Oracle Corporation
    11-May-2018 11:53:34.706 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log CATALINA_BASE:         D:\work\apache-tomcat-8.5.29
    11-May-2018 11:53:34.708 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log CATALINA_HOME:         D:\work\apache-tomcat-8.5.29
    11-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.properties
    11-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.ClassLoaderLogManager
    11-May-2018 11:53:34.710 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djdk.tls.ephemeralDHKeySize=2048
    11-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.webresources
    11-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-8.5.29
    11-May-2018 11:53:34.725 信息 [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcatalina.home=D:\work\apache-tomcat-8.5.29
    11-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\temp
    11-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/read
    11-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/read
    11-May-2018 11:53:36.533 信息 [main] org.apache.catalina.startup.Catalina.load Initialization processed in 2548 ms
    11-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/8.5.29
    11-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] ms
    11-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] ms
    11-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] ms
    11-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] ms
    11-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] ms
    11-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] ms
    11-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 [http://localhost:8080/manager/html][http_localhost_8080_manager_html]

[![cp02_run_tomcat2.png][]][cp02_run_tomcat2.png]

*  4、点击chapter02-2.0.1.RELEASE访问 我们部署的项目。
    
    [![cp02_run_tomcat3.png][]][cp02_run_tomcat3.png]

## 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 ####

*  切入jar文件所在目录，执行命令:

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

*  打开MANIFEST.MF文件

Manifest-Version: 1.0
    Implementation-Title: chapter01 Maven Webapp
    Implementation-Version: 2.0.1.RELEASE
    Built-By: zdwljs
    Implementation-Vendor-Id: chapter02
    Spring-Boot-Version: 2.0.1.RELEASE
    Main-Class: org.springframework.boot.loader.JarLauncher
    Start-Class: com.ricky.SpringBootApplication
    Spring-Boot-Classes: BOOT-INF/classes/
    Spring-Boot-Lib: BOOT-INF/lib/
    Created-By: Apache Maven 3.3.9
    Build-Jdk: 1.8.0_161
    Implementation-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<SpringBootExceptionReporter> 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<Object> sources = getAllSources();
            		Assert.notEmpty(sources, "Sources must not be empty"); 		    
                    //通过 createBeanDefinitionLoader方法 获取lBeanDefinitionLoader 并设置beanNameGenerator、environment、resourceLoader
                   // 最后根据类型进行装载registerbean 常见的类型有xml ,annotation,package,resouces等等 最后返回bean数量
            		load(context, sources.toArray(new Object[0])); 		    
                    // 通过SimpleApplicationEventMulticaster的Executor 去invoke是ApplicationListener类型的listener
                      // 循环执行listener.onApplicationEvent(event);
            		listeners.contextLoaded(context);
            	}

#### 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。

[![SpringBootrunstep.png][]][SpringBootrunstep.png]

## 演示项目地址,欢迎fork和star ##

> 码云：[SpringBootLearn][]

# 最后 #

*  作者ricky
 *  交流群：244930845

#     #

[cp02_run01.png]: /images/20220525/8e6132c5a3c34a46a69abe14e961be39.png
[cp02_run02.png]: /images/20220525/e8d6ecfd5fad44e3b41114b73c509542.png
[cp02_run_tomcat.png]: /images/20220525/c6bda6ad5cd741d2bc1cb78d2b77205c.png
[http_localhost_8080_manager_html]: http://localhost:8080/manager/html
[cp02_run_tomcat2.png]: /images/20220525/082f939a18174cbd978ef6e0aa7241b8.png
[cp02_run_tomcat3.png]: /images/20220525/2d644c31f2dc439fb9e62f80bc0320e8.png
[SpringBootrunstep.png]: /images/20220525/c3313025e52c4cb4a6e0994c2b886ea5.png
[SpringBootLearn]: https://gitee.com/bgt0314/SpringBootLearn