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

筹备环境：

private ConfigurableEnvironment prepareEnvironment(SpringApplicationRunListeners listeners,
            DefaultBootstrapContext bootstrapContext, ApplicationArguments applicationArguments) {
        // Create and configure the environment
        // 如果以后有上下文环境信息，就获取并返回；没有就创立
        // 比方保留底层运行的环境变量
        ConfigurableEnvironment environment = getOrCreateEnvironment();
        // 配置环境（拿到环境信息，命令行参数）configureEnvironment(environment, applicationArguments.getSourceArgs());
        // 绑定环境信息
        ConfigurationPropertySources.attach(environment);
// 监听器调用 listener.environmentPrepared()；告诉所有的监听器以后环境筹备实现
        listeners.environmentPrepared(bootstrapContext, environment);
// 将环境信息设置到类的最初(这个不必管)
        DefaultPropertiesPropertySource.moveToEnd(environment);
        // 配置额定的 Profiles，激活哪些环境(不必管)
        configureAdditionalProfiles(environment);
        // 绑定工作（都是找到一些货色，把一些属性绑定到某个值外面）bindToSpringApplication(environment);
        // 又是筹备一些环境信息
        if (!this.isCustomEnvironment) {environment = new EnvironmentConverter(getClassLoader()).convertEnvironmentIfNecessary(environment,
                    deduceEnvironmentClass());
        }
        // 筹备完了后，把环境信息再次绑定
        ConfigurationPropertySources.attach(environment);
        return environment;
    }

================= 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