spring boot 源码之SpringApplication
run方法
run方法主要创建和初始化ConfigurableApplicationContext,在各个节点调用SpringApplicationRunListener的回调函数,在发送异常时调用用户自定义SpringBootExceptionReporter。调用ApplicationRunner和CommandLineRunner的run方法。
public static ConfigurableApplicationContext run(Class<?>[] primarySources, String[] args) { return new SpringApplication(primarySources).run(args); } public ConfigurableApplicationContext run(String... args) { StopWatch stopWatch = new StopWatch(); stopWatch.start(); ConfigurableApplicationContext context = null; Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>(); configureHeadlessProperty();
//获取SpringApplicationRunListeners并调用starting方法 SpringApplicationRunListeners listeners = getRunListeners(args); listeners.starting(); try { ApplicationArguments applicationArguments = new DefaultApplicationArguments( args); ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments); configureIgnoreBeanInfo(environment); Banner printedBanner = printBanner(environment); context = createApplicationContext(); //创建springApplicationContext exceptionReporters = getSpringFactoriesInstances( SpringBootExceptionReporter.class, new Class[] { ConfigurableApplicationContext.class }, context);//获取SpringBootExceptionReporter prepareContext(context, environment, listeners, applicationArguments, printedBanner);//使用springApplicationContext准备 refreshContext(context);//使用springApplicationContext的refresh方法 afterRefresh(context, applicationArguments);//refresh后的回调函数 listeners.finished(context, null);//调用SpringApplicationRunListener的finished方法 stopWatch.stop(); if (this.logStartupInfo) { new StartupInfoLogger(this.mainApplicationClass) .logStarted(getApplicationLog(), stopWatch); } callRunners(context, applicationArguments); return context; } catch (Throwable ex) { handleRunFailure(context, listeners, exceptionReporters, ex);//处理异常 throw new IllegalStateException(ex); } }
getRunListeners
通过SpringFactoriesLoader从META-INF/spring.factories获取配置的SpringApplicationRunListener并初始化这些类。
private SpringApplicationRunListeners getRunListeners(String[] args) { Class<?>[] types = new Class<?>[] { SpringApplication.class, String[].class }; return new SpringApplicationRunListeners(logger, getSpringFactoriesInstances( SpringApplicationRunListener.class, types, this, args)); } private <T> Collection<T> getSpringFactoriesInstances(Class<T> type) { return getSpringFactoriesInstances(type, new Class<?>[] {}); } private <T> Collection<T> getSpringFactoriesInstances(Class<T> type, Class<?>[] parameterTypes, Object... args) { ClassLoader classLoader = Thread.currentThread().getContextClassLoader(); // Use names and ensure unique to protect against duplicates Set<String> names = new LinkedHashSet<>( SpringFactoriesLoader.loadFactoryNames(type, classLoader)); List<T> instances = createSpringFactoriesInstances(type, parameterTypes, classLoader, args, names); AnnotationAwareOrderComparator.sort(instances); return instances; } @SuppressWarnings("unchecked") private <T> List<T> createSpringFactoriesInstances(Class<T> type, Class<?>[] parameterTypes, ClassLoader classLoader, Object[] args, Set<String> names) { List<T> instances = new ArrayList<>(names.size()); for (String name : names) { try { Class<?> instanceClass = ClassUtils.forName(name, classLoader); Assert.isAssignable(type, instanceClass); Constructor<?> constructor = instanceClass .getDeclaredConstructor(parameterTypes); T instance = (T) BeanUtils.instantiateClass(constructor, args); instances.add(instance); } catch (Throwable ex) { throw new IllegalArgumentException( "Cannot instantiate " + type + " : " + name, ex); } } return instances; }
createApplicationContext
根据不同的应用类型,初始化不同的ApplicationContext。
public static final String DEFAULT_CONTEXT_CLASS = "org.springframework.context."
+ "annotation.AnnotationConfigApplicationContext";
public static final String DEFAULT_WEB_CONTEXT_CLASS = "org.springframework.boot."
+ "web.servlet.context.AnnotationConfigServletWebServerApplicationContext";
public static final String DEFAULT_REACTIVE_WEB_CONTEXT_CLASS = "org.springframework."
+ "boot.web.reactive.context.AnnotationConfigReactiveWebServerApplicationContext";
protected ConfigurableApplicationContext createApplicationContext() { Class<?> contextClass = this.applicationContextClass; if (contextClass == null) { try { switch (this.webApplicationType) { case SERVLET: contextClass = Class.forName(DEFAULT_WEB_CONTEXT_CLASS); break; case REACTIVE: contextClass = Class.forName(DEFAULT_REACTIVE_WEB_CONTEXT_CLASS); break; default: contextClass = Class.forName(DEFAULT_CONTEXT_CLASS); } } catch (ClassNotFoundException ex) { throw new IllegalStateException( "Unable create a default ApplicationContext, " + "please specify an ApplicationContextClass", ex); } } return (ConfigurableApplicationContext) BeanUtils.instantiateClass(contextClass); }
callRunners方法
从spring容器中获取所有的ApplicationRunner和CommandLineRunner然后调用他们的run方法。
private void callRunners(ApplicationContext context, ApplicationArguments args) { List<Object> runners = new ArrayList<>(); runners.addAll(context.getBeansOfType(ApplicationRunner.class).values()); runners.addAll(context.getBeansOfType(CommandLineRunner.class).values()); AnnotationAwareOrderComparator.sort(runners); for (Object runner : new LinkedHashSet<>(runners)) { if (runner instanceof ApplicationRunner) { callRunner((ApplicationRunner) runner, args); } if (runner instanceof CommandLineRunner) { callRunner((CommandLineRunner) runner, args); } } }