原 荐 SpringBoot 2.0 系列0

SpringBoot 2.0 系列002 --运行流程分析

SpringBoot 2.0 系列001 -- 入门介绍以及相关概念

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

<packaging>jar</packaging>

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: 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>
                <!--排除tomcat依赖-->
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <!--引入servlet支持-->
        <!--servlet依赖-->
        <!--httpServletRequest等相关文件-->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
        <!--引入servlet支持结束-->

1.3.2 注意将打包方式改为war形式

<packaging>war</packaging>

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 
  • 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

  • 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

  • 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。

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