关于springboot:82SpringBoot启动流程把spring应用跑起来接81

================= 进入 getOrCreateEnvironment()
private ConfigurableEnvironment getOrCreateEnvironment() {if (this.environment != null) {return this.environment;}
        switch (this.webApplicationType) {
        case SERVLET: // 如果是原生 servlet 编程
            return new StandardServletEnvironment();
        case REACTIVE: // 如果是响应式编程
            return new StandardReactiveWebEnvironment();
        default:
            return new StandardEnvironment();}
    }


==================== 进入 configureEnvironment()
protected void configureEnvironment(ConfigurableEnvironment environment, String[] args) {
        // 给环境增加一些类型转换器
        if (this.addConversionService) {ConversionService conversionService = ApplicationConversionService.getSharedInstance();
            environment.setConversionService((ConfigurableConversionService) conversionService);
        }
        // 加载 (读取) 内部配置源
        // 即读取所有的配置源的配置属性值
        configurePropertySources(environment, args);
        // 激活 Profiles 环境
        configureProfiles(environment, args);
    }
========== 进入 configurePropertySources()
protected void configurePropertySources(ConfigurableEnvironment environment, String[] args) {
        // 获取到所有配置源
        MutablePropertySources sources = environment.getPropertySources();
        DefaultPropertiesPropertySource.ifNotEmpty(this.defaultProperties, sources::addLast);
        // 命令行信息
        if (this.addCommandLineProperties && args.length > 0) {
            String name = CommandLinePropertySource.COMMAND_LINE_PROPERTY_SOURCE_NAME;
            if (sources.contains(name)) {PropertySource<?> source = sources.get(name);
                CompositePropertySource composite = new CompositePropertySource(name);
                composite.addPropertySource(new SimpleCommandLinePropertySource("springApplicationCommandLineArgs", args));
                composite.addPropertySource(source);
                sources.replace(name, composite);
            }
            else {sources.addFirst(new SimpleCommandLinePropertySource(args));
            }
        }
    }

============== 进入 environmentPrepared（）void environmentPrepared(ConfigurableBootstrapContext bootstrapContext, ConfigurableEnvironment environment) {
        doWithListeners("spring.boot.application.environment-prepared",
                (listener) -> listener.environmentPrepared(bootstrapContext, environment));
    }

所有配置源

创立 IOC 容器 createApplicationContext()

protected ConfigurableApplicationContext createApplicationContext() {return this.applicationContextFactory.create(this.webApplicationType);
    }
============= 依据以后的利用类型（Servlet）创立容器
// 以后会创立 AnnotationConfigServletWebServerApplicationContext
ApplicationContextFactory DEFAULT = (webApplicationType) -> {
        try {switch (webApplicationType) {
            case SERVLET:
                return new AnnotationConfigServletWebServerApplicationContext();
            case REACTIVE:
                return new AnnotationConfigReactiveWebServerApplicationContext();
            default:
                return new AnnotationConfigApplicationContext();}
        }
        catch (Exception ex) {
            throw new IllegalStateException("Unable create a default ApplicationContext instance,"
                    + "you may need a custom ApplicationContextFactory", ex);
        }
    };

筹备 ApplicationContext IOC 容器的根本信息 prepareContext()

private void prepareContext(DefaultBootstrapContext bootstrapContext, ConfigurableApplicationContext context,
            ConfigurableEnvironment environment, SpringApplicationRunListeners listeners,
            ApplicationArguments applicationArguments, Banner printedBanner) {
        // 保留后面的根底环境
        context.setEnvironment(environment);
        //IOC 容器的后置解决流程。postProcessApplicationContext(context);
        // 利用初始化器：applyInitializers
        applyInitializers(context);
        listeners.contextPrepared(context);
        bootstrapContext.close(context);
        if (this.logStartupInfo) {logStartupInfo(context.getParent() == null);
            logStartupProfileInfo(context);
        }
        // Add boot specific singleton beans
        ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
        beanFactory.registerSingleton("springApplicationArguments", applicationArguments);
        if (printedBanner != null) {beanFactory.registerSingleton("springBootBanner", printedBanner);
        }
        if (beanFactory instanceof DefaultListableBeanFactory) {((DefaultListableBeanFactory) beanFactory)
                    .setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding);
        }
        if (this.lazyInitialization) {context.addBeanFactoryPostProcessor(new LazyInitializationBeanFactoryPostProcessor());
        }
        // Load the sources
        Set<Object> sources = getAllSources();
        Assert.notEmpty(sources, "Sources must not be empty");
        load(context, sources.toArray(new Object[0]));
        listeners.contextLoaded(context);
    }

================== postProcessApplicationContext(context);
protected void postProcessApplicationContext(ConfigurableApplicationContext context) {if (this.beanNameGenerator != null) {
// 注册组件
            context.getBeanFactory().registerSingleton(AnnotationConfigUtils.CONFIGURATION_BEAN_NAME_GENERATOR,
                    this.beanNameGenerator);
        }

        if (this.resourceLoader != null) {
        // 读取配置文件的资源
            if (context instanceof GenericApplicationContext) {((GenericApplicationContext) context).setResourceLoader(this.resourceLoader);
            }

            if (context instanceof DefaultResourceLoader) {
        // 资源加载器
                ((DefaultResourceLoader) context).setClassLoader(this.resourceLoader.getClassLoader());
            }
        }

        // 筹备类型转换器
        if (this.addConversionService) {context.getBeanFactory().setConversionService(ApplicationConversionService.getSharedInstance());
        }
    }

===================applyInitializers(context)
protected void applyInitializers(ConfigurableApplicationContext context) {
// 遍历所有的 ApplicationContextInitializer。调用 initialize。来对 ioc 容器进行初始化扩大性能
        for (ApplicationContextInitializer initializer : getInitializers()) { // 之前从 spring.factories 找进去的七个 Initializer
            Class<?> requiredType = GenericTypeResolver.resolveTypeArgument(initializer.getClass(),
                    ApplicationContextInitializer.class);
            Assert.isInstanceOf(requiredType, context, "Unable to call initializer.");
            initializer.initialize(context);
        }
    }

@Override
    public void initialize(ConfigurableApplicationContext context) {ConfigurableEnvironment environment = context.getEnvironment();
        List<Class<?>> initializerClasses = getInitializerClasses(environment);
    // 如果 initializerClasses 不为空，就把他们实例化。if (!initializerClasses.isEmpty()) {applyInitializerClasses(context, initializerClasses);
        }
    }

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