上篇回顧

在上一篇refreshContext()刷新應(yīng)用上下文中, 我們主要分析了spring容器的刷新

1. 首先更新刷新狀態(tài)
2. 然后處理beanFactory的后置處理器, 用于注冊bean定義, 其中ConfigurationClassPostProcessor處理器, 處理模塊中@Configuration注解
3. onRefresh()方法中, 實(shí)例化了TomcatWebServer
4. 最后在finishRefresh()中, 實(shí)例化了所有bean

目錄

1. 啟動完成

2. 發(fā)布ApplicationStartedEvent事件

3. 發(fā)布ApplicationReadyEvent事件

4. 異常處理 handleRunFailure

1. 啟動完成

主要發(fā)布了ApplicationStartedEvent, ApplicationReadyEvent事件, 以及啟動失敗異常處理, 發(fā)布啟動失敗事件

public class SpringApplication {
    public ConfigurableApplicationContext run(String... args) {
        StopWatch stopWatch = new StopWatch();
        stopWatch.start();
        ConfigurableApplicationContext context = null;
        Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
        configureHeadlessProperty();
        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();
            exceptionReporters = getSpringFactoriesInstances(
                    SpringBootExceptionReporter.class,
                    new Class[] { ConfigurableApplicationContext.class }, context);
            prepareContext(context, environment, listeners, applicationArguments,
                    printedBanner);
            refreshContext(context);
            
            //本文分析的是下面所有代碼
            
            //沒有執(zhí)行任何操作
            afterRefresh(context, applicationArguments);
            //打印啟動時(shí)間日志
            stopWatch.stop();
            if (this.logStartupInfo) {
                //打印啟動信息
                new StartupInfoLogger(this.mainApplicationClass)
                        .logStarted(getApplicationLog(), stopWatch);
            }
            //發(fā)布ApplicationStartedEvent事件
            listeners.started(context);
            callRunners(context, applicationArguments);
        }
        catch (Throwable ex) {
            //異常處理
            handleRunFailure(context, ex, exceptionReporters, listeners);
            throw new IllegalStateException(ex);
        }

        try {
            //發(fā)布ApplicationReadyEvent事件
            listeners.running(context);
        }
        catch (Throwable ex) {
            //異常處理
            handleRunFailure(context, ex, exceptionReporters, null);
            throw new IllegalStateException(ex);
        }
        return context;
    }
}

2. 發(fā)布ApplicationStartedEvent事件

有兩個(gè)listener關(guān)注了ApplicationStartedEvent事件,

1. BackgroundPreinitializer
   • 擴(kuò)展點(diǎn), 暫不做任何處理
2. DelegatingApplicationListener
   • 擴(kuò)展點(diǎn), 暫不做任何處理

3. 發(fā)布ApplicationReadyEvent事件

有三個(gè)監(jiān)聽器關(guān)注了ApplicationReadyEvent事件

1. SpringApplicationAdminMXBeanRegistrar
   • this.ready設(shè)為true
2. BackgroundPreinitializer
   • 等待或者終止后臺線程
3. DelegatingApplicationListener
   • 擴(kuò)展點(diǎn), 暫不做任何處理

4. 異常處理 handleRunFailure

public class SpringApplication {

    //處理異常
    private void handleRunFailure(ConfigurableApplicationContext context,
            Throwable exception,
            Collection<SpringBootExceptionReporter> exceptionReporters,
            SpringApplicationRunListeners listeners) {
        try {
            try {
                //獲取exitCode編碼
                handleExitCode(context, exception);
                //發(fā)布啟動失敗事件
                if (listeners != null) {
                    listeners.failed(context, exception);
                }
            }
            finally {
                //上報(bào)失敗, 交給exceptionReporters處理
                reportFailure(exceptionReporters, exception);
                if (context != null) {
                    context.close();
                }
            }
        }
        catch (Exception ex) {
            logger.warn("Unable to close ApplicationContext", ex);
        }
        //拋出異常
        ReflectionUtils.rethrowRuntimeException(exception);
    }
}

總結(jié)

到這一步, 整個(gè)springboot的啟動已經(jīng)結(jié)束, 最后發(fā)布了ApplicationStartedEvent, ApplicationReadyEvent事件, 以及啟動失敗異常處理, 發(fā)布啟動失敗事件