SpringBoot的启动配置原理

publicclassSpringApplication {
publicSpringApplication(Class... primarySources) {
this((ResourceLoader)null, primarySources);
    }
publicSpringApplication(ResourceLoaderresourceLoader, Class... primarySources) {
this.sources=newLinkedHashSet();
this.bannerMode=Mode.CONSOLE;
this.logStartupInfo=true;
this.addCommandLineProperties=true;
this.addConversionService=true;
this.headless=true;
this.registerShutdownHook=true;
this.additionalProfiles=newHashSet();
this.isCustomEnvironment=false;
this.resourceLoader=resourceLoader;
Assert.notNull(primarySources, "PrimarySources must not be null");
// 保存主配置类this.primarySources=newLinkedHashSet(Arrays.asList(primarySources));
// 判断当前是否一个web应用this.webApplicationType=WebApplicationType.deduceFromClasspath();                                                            
// 从类路径下找到META-INF/spring.factories配置的所有ApplicationContextInitializer；然后保存起来。this.setInitializers(this.getSpringFactoriesInstances(ApplicationContextInitializer.class));
// 从类路径下找到META-INF/spring.factories配置的所有ApplicationListenerthis.setListeners(this.getSpringFactoriesInstances(ApplicationListener.class));
//从多个配置类中找到有main方法的主配置类this.mainApplicationClass=this.deduceMainApplicationClass();
    }

publicConfigurableApplicationContextrun(String... args) {
StopWatchstopWatch=newStopWatch();
stopWatch.start();
ConfigurableApplicationContextcontext=null;
Collection<SpringBootExceptionReporter>exceptionReporters=newArrayList();
this.configureHeadlessProperty();
// 获取SpringApplicationRunListener; 从类路径下META-INF/spring.factories获取SpringApplicationRunListenerslisteners=this.getRunListeners(args);
// 回调所有的获取SpringApplicationRunListener.starting()方法listeners.starting();
CollectionexceptionReporters;
try {
// 封装命令行参数ApplicationArgumentsapplicationArguments=newDefaultApplicationArguments(args);
// 准备环境ConfigurableEnvironmentenvironment=this.prepareEnvironment(listeners, applicationArguments);
this.configureIgnoreBeanInfo(environment);
// 创建环境完成后回调SpringApplicationRunListener.environmentPrepared();表示环境准备完成BannerprintedBanner=this.printBanner(environment);
// 创建ApplicationContext；决定创建web的IOC还是普通的IOCcontext=this.createApplicationContext();
exceptionReporters=this.getSpringFactoriesInstances(SpringBootExceptionReporter.class, newClass[]{ConfigurableApplicationContext.class}, context);
// 准备上下文环境；将environment保存到IOC中，而且applyInitializers();// 而且applyInitializers():回调之前保存的所有ApplicationContextInitializer的initialize方法// 回调所有的SpringApplicationRunListener的contextPrepared();this.prepareContext(context, environment, listeners, applicationArguments, printedBanner);
// prepareContext运行完成以后回调所有的SpringApplicationRunListener的contextLoaded();// 扫描容器；IOC容器初始化（如果是web应用还会创建嵌入的Tomcat）；// 扫描，创建，加载所有组件的地方(配置类，组件，自动配置)this.refreshContext(context);
// 从IOC容器中获取所有的ApplicationRunner和CommandLineRunner进行回调// ApplicationRunner先回调，CommandLineRunner再回调this.afterRefresh(context, applicationArguments);
stopWatch.stop();
if (this.logStartupInfo) {
                (newStartupInfoLogger(this.mainApplicationClass)).logStarted(this.getApplicationLog(), stopWatch);
            }
listeners.started(context);
this.callRunners(context, applicationArguments);
        } catch (Throwablevar10) {
this.handleRunFailure(context, var10, exceptionReporters, listeners);
thrownewIllegalStateException(var10);
        }
try {
listeners.running(context);
// 整个SpringBoot应用启动完成以后返回启动的IOC容器returncontext;
        } catch (Throwablevar9) {
this.handleRunFailure(context, var9, exceptionReporters, (SpringApplicationRunListeners)null);
thrownewIllegalStateException(var9);
        }
    }

publicclassCustomApplicationContextInitializerimplementsApplicationContextInitializer<ConfigurableApplicationContext> {
@Overridepublicvoidinitialize(ConfigurableApplicationContextconfigurableApplicationContext) {
System.out.println("ApplicationContextInitializer.....initialize");
    }
}

publicclassCustomSrpingApplicationRunListenerimplementsSpringApplicationRunListener {
// 必须有的构造器publicCustomSrpingApplicationRunListener(SpringApplicationapplication,String[] args){
    }
@Overridepublicvoidstarting() {
System.out.println("SpringApplicationRunListener...starting....");
    }
@OverridepublicvoidenvironmentPrepared(ConfigurableEnvironmentenvironment) {
Objecto=environment.getSystemEnvironment().get("os.name");
System.out.println("SpringApplicationRunListener...environmentPrepared...."+o);
    }
@OverridepublicvoidcontextPrepared(ConfigurableApplicationContextcontext) {
System.out.println("SpringApplicationRunListener..contextPrepared");
    }
@OverridepublicvoidcontextLoaded(ConfigurableApplicationContextcontext) {
System.out.println("SpringApplicationRunListener..contextLoaded");
    }
@Overridepublicvoidstarted(ConfigurableApplicationContextcontext) {
System.out.println("SpringApplicationRunListener..started");
    }
@Overridepublicvoidrunning(ConfigurableApplicationContextcontext) {
System.out.println("SpringApplicationRunListener..running");
    }
@Overridepublicvoidfailed(ConfigurableApplicationContextcontext, Throwableexception) {
System.out.println("SpringApplicationRunListener..failed");
    }
}

org.springframework.context.ApplicationContextInitializer=com.desperado.demo.CustomApplicationContextInitializerorg.springframework.boot.SpringApplicationRunListener=com.desperado.demo.CustomSrpingApplicationRunListener

@ComponentpublicclassCustomApplicationRunnerimplementsApplicationRunner {
@Overridepublicvoidrun(ApplicationArgumentsargs) {
System.out.println("ApplicationRunner ... run....");
    }
}

@ComponentpublicclassCustomCommandLineRunnerimplementsCommandLineRunner {
@Overridepublicvoidrun(String... args) {
System.out.println("commandLineRunner ... run ...");
    }
}

@ConfigurationProperties(prefix="desperado.custom")
publicclassCustomProperties {
privateStringprefix;
privateStringsuffix;
publicStringgetPrefix() {
returnprefix;
    }
publicvoidsetPrefix(Stringprefix) {
this.prefix=prefix;
    }
publicStringgetSuffix() {
returnsuffix;
    }
publicvoidsetSuffix(Stringsuffix) {
this.suffix=suffix;
    }
}

publicclassCustomService {
CustomPropertiescustomProperties;
publicCustomPropertiesgetCustomProperties(){
returncustomProperties;
    }
publicvoidsetCustomProperties(CustomPropertiescustomProperties){
this.customProperties=customProperties;
    }
publicStringsayHello(Stringname){
returncustomProperties.getPrefix()+"-"+name+customProperties.getSuffix();
    }
}

@ConditionalOnWebApplication@EnableConfigurationProperties(CustomProperties.class)
publicclassCustomServiceAutoConfiguration {
@AutowiredCustomPropertiescustomProperties;
@BeanpublicCustomServicecustomService(){
CustomServicecustomService=newCustomService();
customService.setCustomProperties(customProperties);
returncustomService;
    }
}