springboot情操陶冶-SpringApplication(二)

SpringApplication#run()

public ConfigurableApplicationContext run(String... args) {
StopWatch stopWatch = new StopWatch();
stopWatch.start();
ConfigurableApplicationContext context = null;
Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
// 读取java.awt.headless系统变量，默认为true.常用于linux图片的渲染
configureHeadlessProperty();
// 获取SpringApplicationRunListener接口集合并实例化调用公共接口starting()
SpringApplicationRunListeners listeners = getRunListeners(args);
listeners.starting();
try {
ApplicationArguments applicationArguments = new DefaultApplicationArguments(
args);
// environment configuration
ConfigurableEnvironment environment = prepareEnvironment(listeners,
applicationArguments);
// spring.beaninfo.ignore属性读取
configureIgnoreBeanInfo(environment);
// springboot的banner样图
Banner printedBanner = printBanner(environment);
// 创建spring应用上下文(尚未刷新)
context = createApplicationContext();
// SpringBootExceptionReporter接口集合读取
exceptionReporters = getSpringFactoriesInstances(
SpringBootExceptionReporter.class,
new Class[] { ConfigurableApplicationContext.class }, context);
// applicationContext configuration
prepareContext(context, environment, listeners, applicationArguments,
printedBanner);
// 刷新spring应用上下文
refreshContext(context);
afterRefresh(context, applicationArguments);
stopWatch.stop();
if (this.logStartupInfo) {
new StartupInfoLogger(this.mainApplicationClass)
.logStarted(getApplicationLog(), stopWatch);
}
// SpringApplicationRunListener接口的started()方法调用
listeners.started(context);
callRunners(context, applicationArguments);
}
catch (Throwable ex) {
handleRunFailure(context, ex, exceptionReporters, listeners);
throw new IllegalStateException(ex);
}

try {
// SpringApplicationRunListener接口的running()方法调用
listeners.running(context);
}
catch (Throwable ex) {
handleRunFailure(context, ex, exceptionReporters, null);
throw new IllegalStateException(ex);
}
return context;
}

SpringApplication#getRunListeners()

public EventPublishingRunListener(SpringApplication application, String[] args) {
this.application = application;
this.args = args;
this.initialMulticaster = new SimpleApplicationEventMulticaster();
for (ApplicationListener<?> listener : application.getListeners()) {
this.initialMulticaster.addApplicationListener(listener);
}
}

@Override
public void starting() {
this.initialMulticaster.multicastEvent(
new ApplicationStartingEvent(this.application, this.args));
}

SpringApplication#prepareEnvironment()

private ConfigurableEnvironment prepareEnvironment(
SpringApplicationRunListeners listeners,
ApplicationArguments applicationArguments) {
// Create and configure the environment
ConfigurableEnvironment environment = getOrCreateEnvironment();
// 解析args参数和spring.profiles.active配置读取
configureEnvironment(environment, applicationArguments.getSourceArgs());
// 触发ApplicationEnvironmentPreparedEvent事件
listeners.environmentPrepared(environment);
bindToSpringApplication(environment);
if (this.webApplicationType == WebApplicationType.NONE) {
environment = new EnvironmentConverter(getClassLoader())
.convertToStandardEnvironmentIfNecessary(environment);
}
ConfigurationPropertySources.attach(environment);
return environment;
}

commandLineArgs

spring.profiles.active

spring.profiles.active

configurationProperties

SpringApplication#configureIgnoreBeanInfo()

spring.beaninfo.ignore

SpringApplication#printBanner()

.   ____          _            __ _ _
/\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/  ___)| |_)| | | | | || (_| |  ) ) ) )
'  |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot ::        (v2.0.3.RELEASE)

SpringApplication#createApplicationContext()

SpringApplication#prepareContext()

SpringApplication#applyInitializers()

protected void applyInitializers(ConfigurableApplicationContext context) {
for (ApplicationContextInitializer initializer : getInitializers()) {
// 检查相应的ApplicationContextInitializer实体类所接收的泛型实体class
Class<?> requiredType = GenericTypeResolver.resolveTypeArgument(
initializer.getClass(), ApplicationContextInitializer.class);
// 只对接收的泛型为ConfigurableApplicationContext.class进行相应的初始化
Assert.isInstanceOf(requiredType, context, "Unable to call initializer.");
initializer.initialize(context);
}
}

SpringApplication#load()

// 此处的source一般为main函数所在的class，也可通过SpringApplication#setSource()来新增
protected void load(ApplicationContext context, Object[] sources) {
if (logger.isDebugEnabled()) {
logger.debug(
"Loading source " + StringUtils.arrayToCommaDelimitedString(sources));
}
BeanDefinitionLoader loader = createBeanDefinitionLoader(
getBeanDefinitionRegistry(context), sources);
if (this.beanNameGenerator != null) {
loader.setBeanNameGenerator(this.beanNameGenerator);
}
if (this.resourceLoader != null) {
loader.setResourceLoader(this.resourceLoader);
}
if (this.environment != null) {
loader.setEnvironment(this.environment);
}
// 加载beans
loader.load();
}

BeanDefinitionLoader(BeanDefinitionRegistry registry, Object... sources) {
Assert.notNull(registry, "Registry must not be null");
Assert.notEmpty(sources, "Sources must not be empty");
this.sources = sources;
// 注解解析类
this.annotatedReader = new AnnotatedBeanDefinitionReader(registry);
// xml解析类
this.xmlReader = new XmlBeanDefinitionReader(registry);
if (isGroovyPresent()) {
this.groovyReader = new GroovyBeanDefinitionReader(registry);
}
// classpath扫描类，并屏蔽指定的sources类
this.scanner = new ClassPathBeanDefinitionScanner(registry);
this.scanner.addExcludeFilter(new ClassExcludeFilter(sources));
}

@Configuration/@Autowired/@Required

public int load() {
int count = 0;
for (Object source : this.sources) {
count += load(source);
}
return count;
}

private int load(Object source) {
Assert.notNull(source, "Source must not be null");
if (source instanceof Class<?>) {
return load((Class<?>) source);
}
if (source instanceof Resource) {
return load((Resource) source);
}
if (source instanceof Package) {
return load((Package) source);
}
if (source instanceof CharSequence) {
return load((CharSequence) source);
}
throw new IllegalArgumentException("Invalid source type " + source.getClass());
}
// 笔者重点关注此处
private int load(Class<?> source) {
if (isGroovyPresent()
&& GroovyBeanDefinitionSource.class.isAssignableFrom(source)) {
// Any GroovyLoaders added in beans{} DSL can contribute beans here
GroovyBeanDefinitionSource loader = BeanUtils.instantiateClass(source,
GroovyBeanDefinitionSource.class);
load(loader);
}
// 查看class是否被@Component修饰过。此处多用于加载main类
if (isComponent(source)) {
// 注册bean
this.annotatedReader.register(source);
return 1;
}
return 0;
}

@Component

@SpringApplication

SpringApplication#refresh()

异常处理

小结

@SpringBootApplication