springboot 源码笔记
1.springAppication构造器
基于getSpringFactoriesInstances方法构造如下类(获取文件内容在META-INF/spring.factories文件中)
1.1 初始化ApplicationContextInitializer.class
# Application Context Initializers org.springframework.context.ApplicationContextInitializer=\ org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer,\ org.springframework.boot.context.ContextIdApplicationContextInitializer,\ org.springframework.boot.context.config.DelegatingApplicationContextInitializer,\ org.springframework.boot.web.context.ServerPortInfoApplicationContextInitializer
1.2 初始化ApplicationListener.class
# Application Listeners
org.springframework.context.ApplicationListener=\
org.springframework.boot.ClearCachesApplicationListener,\
org.springframework.boot.builder.ParentContextCloserApplicationListener,\
org.springframework.boot.context.FileEncodingApplicationListener,\
org.springframework.boot.context.config.AnsiOutputApplicationListener,\
org.springframework.boot.context.config.ConfigFileApplicationListener,\
org.springframework.boot.context.config.DelegatingApplicationListener,\
org.springframework.boot.context.logging.ClasspathLoggingApplicationListener,\
org.springframework.boot.context.logging.LoggingApplicationListener,\
org.springframework.boot.liquibase.LiquibaseServiceLocatorApplicationListener
2.run方法
StopWatch stopWatch = new StopWatch();//构造时间观察器
stopWatch.start();// 打印一个开始时间
ConfigurableApplicationContext context = null;
Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
configureHeadlessProperty();// 配置headless 依据java.awt.headless
SpringApplicationRunListeners listeners = getRunListeners(args);// 解析如下
// getSpringFactoriesInstances方法获取SpringApplicationRunListener.class对象->EventPublishingRunListener对象
// EventPublishingRunListener对象初始化时,构造器内会执行下面的逻辑
//SimpleApplicationEventMulticaster广播器初始化,并且将listener设置到广播器中
// 将上面获取到的EventPublishingRunListener对象对象添加到SpringApplicationRunListeners对象中
listeners.starting(); // 解析如下
// 调用EventPublishingRunListener对象的starting方法
// 将ApplicationStartingEvent广播出去 SimpleApplicationEventMulticaster->multicastEvent方法
// 调用getApplicationListeners方法获取所有listeners,然后循环广播
// 调用支持事件的listener的listener.onApplicationEvent(event);方法,驱动listener巡行
// 此处支持的listener如下
// org.springframework.boot.logging.LoggingApplicationListener,
// org.springframework.boot.autoconfigure.BackgroundPreinitializer,
// org.springframework.boot.context.config.DelegatingApplicationListener,
// org.springframework.boot.liquibase.LiquibaseServiceLocatorApplicationListener
try {
ApplicationArguments applicationArguments = new DefaultApplicationArguments(
args);
// 创建一个DefaultApplicationArguments对象,构造器中构造了一个新的SOURCE对象
// 根据SOURCE对象的继承结构->SimpleCommandLinePropertySource->parse方法
// 如果args是–开头的,就加入OptionArg中,否则加入到NonOptionArg中
// CommandLinePropertySource构造其中commandLineArgs存入source
ConfigurableEnvironment environment = prepareEnvironment(listeners,
applicationArguments);
// 参照下面的prepareEnvironment方法分析
configureIgnoreBeanInfo(environment);
Banner printedBanner = printBanner(environment); // 打印banner
context = createApplicationContext();
// 创建applicationContext
// 添加AnnotationTypeFilter–>Component 添加AnnotationTypeFilter –> ManagedBean 添加AnnotationTypeFilter –> javax.inject.Named
//
exceptionReporters = getSpringFactoriesInstances(
SpringBootExceptionReporter.class,
new Class[] { ConfigurableApplicationContext.class }, context);
// 异常处理
prepareContext(context, environment, listeners, applicationArguments,
printedBanner);
//
refreshContext(context);
//
afterRefresh(context, applicationArguments);
stopWatch.stop();
if (this.logStartupInfo) {
new StartupInfoLogger(this.mainApplicationClass)
.logStarted(getApplicationLog(), stopWatch);
}
listeners.started(context);
callRunners(context, applicationArguments);
}
prepareEnvironment方法分析
private ConfigurableEnvironment prepareEnvironment(
SpringApplicationRunListeners listeners,
ApplicationArguments applicationArguments) {
// Create and configure the environment
ConfigurableEnvironment environment = getOrCreateEnvironment();
// 获取或者创建ConfigurableEnvironment 构造environment对象 继承AbstractEnvironment
// AbstractEnvironment构造器中调用customizePropertySources方法
// StandardEnvironment对象:配置systemEnvironment systemProperties
// StandardServletEnvironment对象:配置servletContextInitParams servletConfigInitParams jndiProperties
configureEnvironment(environment, applicationArguments.getSourceArgs());
// 配置环境的信息
// configurePropertySources 配置PropertySources
// commandLineArgs、servletConfigInitParams、servletContextInitParams、jndiProperties（如果存在）、
// systemProperties、systemEnvironment、defaultProperties（如果存在）
// configureProfiles 配置Profiles
// 至于哪个具体的配置文件会被加载，需要在application.properties文件中通过spring.profiles.active属性来设置，其值对应{profile}值。
// application-dev.properties：开发环境 application-test.properties：测试环境 application-prod.properties：生产环境
listeners.environmentPrepared(environment);
// 通知所有的观察者,发送ApplicationEnvironmentPreparedEvent事件.
// org.springframework.boot.context.config.ConfigFileApplicationListener,
// org.springframework.boot.context.config.AnsiOutputApplicationListener,
// org.springframework.boot.logging.LoggingApplicationListener,
// org.springframework.boot.logging.ClasspathLoggingApplicationListener,
// org.springframework.boot.autoconfigure.BackgroundPreinitializer,
// org.springframework.boot.context.config.DelegatingApplicationListener,
// org.springframework.boot.context.FileEncodingApplicationListener
//
bindToSpringApplication(environment);
if (!this.isCustomEnvironment) {
environment = new EnvironmentConverter(getClassLoader())
.convertEnvironmentIfNecessary(environment, deduceEnvironmentClass());
}
ConfigurationPropertySources.attach(environment);
return environment;
}
prepareContext分析
private void prepareContext(ConfigurableApplicationContext context,
ConfigurableEnvironment environment, SpringApplicationRunListeners listeners,
ApplicationArguments applicationArguments, Banner printedBanner) {
// 1. 上下文设置环境
context.setEnvironment(environment);
// 2. 调用postProcessApplicationContext方法设置上下文的beanNameGenerator和resourceLoader(如果SpringApplication有的话)
postProcessApplicationContext(context);
// 3. 拿到之前实例化SpringApplication对象的时候设置的ApplicationContextInitializer，调用它们的initialize方法，对上下文做初始化
applyInitializers(context);
// 4. contextPrepareds 是一个空实现
listeners.contextPrepared(context);
// 5. 打印启动日志
if (this.logStartupInfo) {
logStartupInfo(context.getParent() == null);
logStartupProfileInfo(context);
}
// Add boot specific singleton beans
// 6. 日志往上下文的beanFactory中注册一个singleton的bean，bean的名字是springApplicationArguments，bean的实例是之前实例化的ApplicationArguments对象
context.getBeanFactory().registerSingleton("springApplicationArguments",
applicationArguments);
// 如果之前获取的printedBanner不为空，那么往上下文的beanFactory中注册一个singleton的bean，bean的名字是springBootBanner，bean的实例就是这个printedBanner
if (printedBanner != null) {
context.getBeanFactory().registerSingleton("springBootBanner", printedBanner);
}
// Load the sources
Set<Object> sources = getSources();
Assert.notEmpty(sources, "Sources must not be empty");
// 7. 调用load方法注册启动类的bean定义，也就是调用SpringApplication.run(Application.class, args);的类，SpringApplication的load方法内会创建BeanDefinitionLoader的对象，并调用它的load()方法
load(context, sources.toArray(new Object[sources.size()]));
// 8. 调用listeners的contextLoaded方法，说明上下文已经加载，该方法先找到所有的ApplicationListener，遍历这些listener，如果该listener继承了ApplicationContextAware类，那么在这一步会调用它的setApplicationContext方法，设置context
listeners.contextLoaded(context);
}
# Environment Post Processors org.springframework.boot.env.EnvironmentPostProcessor=\ org.springframework.boot.cloud.CloudFoundryVcapEnvironmentPostProcessor,\ org.springframework.boot.env.SpringApplicationJsonEnvironmentPostProcessor,\ org.springframework.boot.env.SystemEnvironmentPropertySourceEnvironmentPostProcessor
1.SpringFactoriesLoader类
loadFactoryNames->loadSpringFactories->META-INF/spring.factories
位置:spring-boot-2.0.5.RELEASE-sources.jar目录下
