一、ApplicationContext

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用户10865967

修改于 2024-10-20 11:04:11

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文章被收录于专栏：SpringBoot 源码解析SpringBoot 源码解析

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（一）Applicaiont 继承关系解读

ApplicationContext 分别继承了以下接口：

ResourcePatternResolver：解析和加载资源

MessageSource：国际化

BeanFactory：Bean 容器

EnvironmentCapable：获取应用环境配置

ApplicationEventPublisher：发布事件

（二）构建ApplicationContext 对象

@SpringBootApplication
public class SpringSourceCodeTestApplication {

    public static void main(String[] args) {
        ConfigurableApplicationContext springBootContext = SpringApplication.run(SpringSourceCodeTestApplication.class, args);
    }

}

（三）SpringApplication.run

run 方法向下追溯可以追溯到org.springframework.boot.SpringApplication#run(java.lang.Class<?>[], java.lang.String[])方法，该方法可以分为两个步骤，第一个步骤为创建SpringApplication对象，第二个步骤为基于该对象调用run方法

public static ConfigurableApplicationContext run(Class<?>[] primarySources, String[] args) {
    return (new SpringApplication(primarySources)).run(args);
}

（四）创建SpringApplication对象

创建SpringApplication对象可以分为以下几步：

1. 使用常量值初始化一些字段

2. 设置主类

3. 推断web应用类型

4. 从代码目录和jar包目录下的META-INF/spring.factories文件中加载key为org.springframework.boot.BootstrapRegistryInitializer的values，并基于这些values对应的类创建对象保存到

bootstrapRegistryInitializers容器中

5. 从代码目录和jar包目录下的META-INF/spring.factories文件中加载key为org.springframework.context.ApplicationContextInitializer的values，并基于这些values对应的类创建对象保存到listeners容器中

6. 从代码目录和jar包目录下的META-INF/spring.factories文件中加载key为org.springframework.context.ApplicationListener的values，并基于这些values对应的类创建对象保存到initializers 容器中

7. 基于当前的栈查找main 方法所属的类，基于该类创建实例并赋值给mainApplicationClass

public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
    this.sources = new LinkedHashSet();
    this.bannerMode = Mode.CONSOLE;
    this.logStartupInfo = true;
    this.addCommandLineProperties = true;
    this.addConversionService = true;
    this.headless = true;
    this.registerShutdownHook = true;
    this.additionalProfiles = Collections.emptySet();
    this.isCustomEnvironment = false;
    this.lazyInitialization = false;
    this.applicationContextFactory = ApplicationContextFactory.DEFAULT;
    this.applicationStartup = ApplicationStartup.DEFAULT;
    this.resourceLoader = resourceLoader;
    Assert.notNull(primarySources, "PrimarySources must not be null");
    this.primarySources = new LinkedHashSet(Arrays.asList(primarySources));
    this.webApplicationType = WebApplicationType.deduceFromClasspath();
    this.bootstrapRegistryInitializers = new ArrayList(this.getSpringFactoriesInstances(BootstrapRegistryInitializer.class));
    this.setInitializers(this.getSpringFactoriesInstances(ApplicationContextInitializer.class));
    this.setListeners(this.getSpringFactoriesInstances(ApplicationListener.class));
    this.mainApplicationClass = this.deduceMainApplicationClass();
}

（五）org.springframework.boot.SpringApplication#run(java.lang.String...)

run方法可以分为以下几步：

1. 创建一个bootStrapContext容器，并基于initializers中的initializer回调初始化

2. 配置java.awt.headless属性

3. 构建事件发布器：从代码目录和jar包目录下的META-INF/spring.factories文件中加载key为org.springframework.boot.SpringApplicationRunListener的values，并基于这些values对应的类创建对象保存到

SpringApplicationRunListeners对象中

4. 使用事件发布器发布容器启动事件

5. 设置应用环境配置

6. 打印Banner

7. 创建context实例

8. 准备容器

9. 刷新容器

10. 容器后处理

11. 发布容器已启动事件

public ConfigurableApplicationContext run(String... args) {
    long startTime = System.nanoTime();
    DefaultBootstrapContext bootstrapContext = this.createBootstrapContext();
    ConfigurableApplicationContext context = null;
    this.configureHeadlessProperty();
    SpringApplicationRunListeners listeners = this.getRunListeners(args);
    listeners.starting(bootstrapContext, this.mainApplicationClass);

    Throwable ex;
    try {
        ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
        ConfigurableEnvironment environment = this.prepareEnvironment(listeners, bootstrapContext, applicationArguments);
        this.configureIgnoreBeanInfo(environment);
        Banner printedBanner = this.printBanner(environment);
        context = this.createApplicationContext();
        context.setApplicationStartup(this.applicationStartup);
        this.prepareContext(bootstrapContext, context, environment, listeners, applicationArguments, printedBanner);
        this.refreshContext(context);
        this.afterRefresh(context, applicationArguments);
        Duration timeTakenToStartup = Duration.ofNanos(System.nanoTime() - startTime);
        if (this.logStartupInfo) {
            (new StartupInfoLogger(this.mainApplicationClass)).logStarted(this.getApplicationLog(), timeTakenToStartup);
        }

        listeners.started(context, timeTakenToStartup);
        this.callRunners(context, applicationArguments);
    } catch (Throwable var12) {
        ex = var12;
        this.handleRunFailure(context, ex, listeners);
        throw new IllegalStateException(ex);
    }

    try {
        Duration timeTakenToReady = Duration.ofNanos(System.nanoTime() - startTime);
        listeners.ready(context, timeTakenToReady);
        return context;
    } catch (Throwable var11) {
        ex = var11;
        this.handleRunFailure(context, ex, (SpringApplicationRunListeners)null);
        throw new IllegalStateException(ex);
    }
}

原创声明：本文系作者授权腾讯云开发者社区发表，未经许可，不得转载。

如有侵权，请联系 cloudcommunity@tencent.com 删除。

spring boot

原创声明：本文系作者授权腾讯云开发者社区发表，未经许可，不得转载。

如有侵权，请联系 cloudcommunity@tencent.com 删除。

spring boot

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