Springboot启动原理和自动配置原理解析

Elina ·

更新时间:2024-09-20

· 111 次阅读

启动原理

SpringApplication

1、初始化

2、调用run方法

自动配置原理

放本地文件夹都快吃土了，准备清理文件夹，关于Springboot的！

启动原理

@SpringBootApplication
public class Start {
    public static void main(String[] args) {
        SpringApplication.run(Start.class, args);
    }
}

SpringApplication 1、初始化

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

 public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
        this.sources = new LinkedHashSet(); // 
        this.bannerMode = Mode.CONSOLE;// 控制banner
        this.logStartupInfo = true;// 是否启动日志
        this.addCommandLineProperties = true; // 读取命令行配置
        this.addConversionService = true; //添加转换器
        this.headless = true; // 
        this.registerShutdownHook = true; // 注册重启
        this.additionalProfiles = Collections.emptySet();// 读取配置环境
        this.isCustomEnvironment = false;// 是否是自定义环境
        this.lazyInitialization = false; // 是否懒加载
        this.applicationContextFactory = ApplicationContextFactory.DEFAULT;
        this.applicationStartup = ApplicationStartup.DEFAULT; // ApplicationStartup DEFAULT = new DefaultApplicationStartup();
        this.resourceLoader = resourceLoader;// 资源加载器
        Assert.notNull(primarySources, "PrimarySources must not be null");
        this.primarySources = new LinkedHashSet(Arrays.asList(primarySources)); // 主程序
        this.webApplicationType = WebApplicationType.deduceFromClasspath();//  SERVLET||REACTIVE; 是servlet还是reactive环境
        // BootstrapRegistryInitializer
this.bootstrapRegistryInitializers = new ArrayList(this.getSpringFactoriesInstances(BootstrapRegistryInitializer.class));
        // ApplicationContextInitializer
this.setInitializers(this.getSpringFactoriesInstances(ApplicationContextInitializer.class));
// ApplicationListener        
this.setListeners(this.getSpringFactoriesInstances(ApplicationListener.class));
        this.mainApplicationClass = this.deduceMainApplicationClass();
    }

注册 BootstrapRegistryInitializer

this.bootstrapRegistryInitializers = new ArrayList(this.getSpringFactoriesInstances(BootstrapRegistryInitializer.class));
// 
private <T> Collection<T> getSpringFactoriesInstances(Class<T> type, Class<?>[] parameterTypes, Object... args) {
        ClassLoader classLoader = this.getClassLoader();
        // 1、从配置文件读取名称加载
        Set<String> names = new LinkedHashSet(SpringFactoriesLoader.loadFactoryNames(type, classLoader));
        // 2、获取构造器实例
 List<T> instances = this.createSpringFactoriesInstances(type, parameterTypes, classLoader, args, names);
        // 3、排序
 AnnotationAwareOrderComparator.sort(instances);
        return instances;
}
// 1、加载配置
 private static Map<String, List<String>> loadSpringFactories(ClassLoader classLoader) {
        Map<String, List<String>> result = (Map)cache.get(classLoader);
        if (result != null) {
            return result;
        } else {
            HashMap result = new HashMap();
            try {
                 //核心 从这里知道读取配置文件位置 默认
                Enumeration urls = classLoader.getResources("META-INF/spring.factories");
// ... 这里省略迭代器遍历注册
                result.replaceAll((factoryType, implementations) -> {
                    return (List)implementations.stream().distinct().collect(Collectors.collectingAndThen(Collectors.toList(), Collections::unmodifiableList));
                });
// 添加到缓存中，下次读取。根据类名读取
                cache.put(classLoader, result);
                return result;
            } catch (IOException var14) {
                throw new IllegalArgumentException("Unable to load factories from location [META-INF/spring.factories]", var14);
            }
        }
    }
// 2、获取构造器实例
private <T> List<T> createSpringFactoriesInstances(Class<T> type, Class<?>[] parameterTypes, ClassLoader classLoader, Object[] args, Set<String> names) {
        List<T> instances = new ArrayList(names.size());
        Iterator var7 = names.iterator();
        while(var7.hasNext()) {
            String name = (String)var7.next();
            try {
                // 通过类名反射机制调用，读取Class<T> class
                Class<?> instanceClass = ClassUtils.forName(name, classLoader);
                Assert.isAssignable(type, instanceClass);
                Constructor<?> constructor = instanceClass.getDeclaredConstructor(parameterTypes);
                // 获取构造器实例
 T instance = BeanUtils.instantiateClass(constructor, args);
                // 添加到构造器中
                instances.add(instance);
            } catch (Throwable var12) {
                throw new IllegalArgumentException("Cannot instantiate " + type + " : " + name, var12);
            }
        }
// 返回
        return instances;
    }
// 排序 通过debug这里调用的是Integer类型排序方法 List<Integer> list
  public static void sort(List<?> list) {
        if (list.size() > 1) {
            list.sort(INSTANCE);
        }
    }

配置文件

spring-boot:2.7.1.META-INF\spring.factorie

org.springframework.context.ApplicationContextInitializer=\
org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer,\
org.springframework.boot.context.ContextIdApplicationContextInitializer,\
org.springframework.boot.context.config.DelegatingApplicationContextInitializer,\
org.springframework.boot.rsocket.context.RSocketPortInfoApplicationContextInitializer,\
org.springframework.boot.web.context.ServerPortInfoApplicationContextInitializer

像 BootstrapRegistryInitializer

另外几个配置是从其他配置文件中读取的

例如

注册 ApplicationContextInitializer 、ApplicationListener

同 BootstrapRegistryInitializer加载原理

2、调用run方法

核心

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);
        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);
            // 加载所有注解使用的扫描的组件
    this.refreshContext(context);
    // 刷新
            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) {
            this.handleRunFailure(context, var12, listeners);
            throw new IllegalStateException(var12);
        }
        try {
            Duration timeTakenToReady = Duration.ofNanos(System.nanoTime() - startTime);
            listeners.ready(context, timeTakenToReady);
            return context;
        } catch (Throwable var11) {
            this.handleRunFailure(context, var11, (SpringApplicationRunListeners)null);
            throw new IllegalStateException(var11);
        }
    }

所有组件经过org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader方法加载注册组件

private void registerBeanDefinitionForImportedConfigurationClass(ConfigurationClass configClass) {
        AnnotationMetadata metadata = configClass.getMetadata();
        AnnotatedGenericBeanDefinition configBeanDef = new AnnotatedGenericBeanDefinition(metadata);
        ScopeMetadata scopeMetadata = scopeMetadataResolver.resolveScopeMetadata(configBeanDef);
        configBeanDef.setScope(scopeMetadata.getScopeName());
        String configBeanName = this.importBeanNameGenerator.generateBeanName(configBeanDef, this.registry);
        AnnotationConfigUtils.processCommonDefinitionAnnotations(configBeanDef, metadata);
        BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(configBeanDef, configBeanName);
        definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
        // 在这里注册
this.registry.registerBeanDefinition(definitionHolder.getBeanName(), definitionHolder.getBeanDefinition());
        configClass.setBeanName(configBeanName);
        if (logger.isTraceEnabled()) {
            logger.trace("Registered bean definition for imported class '" + configBeanName + "'");
        }
    }

org.springframework.beans.factory.support.DefaultListableBeanFactory

registerBeanDefinition(definitionHolder.getBeanName(), definitionHolder.getBeanDefinition())

@Override
public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)
throws BeanDefinitionStoreException {
Assert.hasText(beanName, "Bean name must not be empty");
Assert.notNull(beanDefinition, "BeanDefinition must not be null");
if (beanDefinition instanceof AbstractBeanDefinition) {
try {
((AbstractBeanDefinition) beanDefinition).validate();
}
catch (BeanDefinitionValidationException ex) {
throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName,
"Validation of bean definition failed", ex);
}
}
BeanDefinition existingDefinition = this.beanDefinitionMap.get(beanName);
if (existingDefinition != null) {
if (!isAllowBeanDefinitionOverriding()) {
throw new BeanDefinitionOverrideException(beanName, beanDefinition, existingDefinition);
}
else if (existingDefinition.getRole() < beanDefinition.getRole()) {
// e.g. was ROLE_APPLICATION, now overriding with ROLE_SUPPORT or ROLE_INFRASTRUCTURE
if (logger.isInfoEnabled()) {
logger.info("Overriding user-defined bean definition for bean '" + beanName +
"' with a framework-generated bean definition: replacing [" +
existingDefinition + "] with [" + beanDefinition + "]");
}
}
else if (!beanDefinition.equals(existingDefinition)) {
if (logger.isDebugEnabled()) {
logger.debug("Overriding bean definition for bean '" + beanName +
"' with a different definition: replacing [" + existingDefinition +
"] with [" + beanDefinition + "]");
}
}
else {
if (logger.isTraceEnabled()) {
logger.trace("Overriding bean definition for bean '" + beanName +
"' with an equivalent definition: replacing [" + existingDefinition +
"] with [" + beanDefinition + "]");
}
}
// 注册
this.beanDefinitionMap.put(beanName, beanDefinition);
}
else {
if (hasBeanCreationStarted()) {
// Cannot modify startup-time collection elements anymore (for stable iteration)
synchronized (this.beanDefinitionMap) {
this.beanDefinitionMap.put(beanName, beanDefinition);
List<String> updatedDefinitions = new ArrayList<>(this.beanDefinitionNames.size() + 1);
updatedDefinitions.addAll(this.beanDefinitionNames);
updatedDefinitions.add(beanName);
this.beanDefinitionNames = updatedDefinitions;
removeManualSingletonName(beanName);
}
}
else {
// Still in startup registration phase
this.beanDefinitionMap.put(beanName, beanDefinition);
this.beanDefinitionNames.add(beanName);
removeManualSingletonName(beanName);
}
this.frozenBeanDefinitionNames = null;
}
if (existingDefinition != null || containsSingleton(beanName)) {
resetBeanDefinition(beanName);
}
else if (isConfigurationFrozen()) {
clearByTypeCache();
}
}

自动配置原理

该部分暂时找不到了，之前备份找不到了，先TODO下吧!喜欢的朋友参考下这篇文章：https://www.jb51.net/article/266763.htm

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