首先放一张接口设计图:
spring-boot 启动分析
SpringApplication.run(BlogApplication.class, args);
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跟踪到
private void initialize(Object[] sources) {
if(sources != null && sources.length > 0) {
this.sources.addAll(Arrays.asList(sources));
}
this.webEnvironment = this.deduceWebEnvironment();
//加载所有jar中spring-factories下的所有工厂
this.setInitializers(this.getSpringFactoriesInstances(ApplicationContextInitializer.class));
this.setListeners(this.getSpringFactoriesInstances(ApplicationListener.class));
this.mainApplicationClass = this.deduceMainApplicationClass();
}
public static List loadFactoryNames(Class factoryClass, ClassLoader classLoader) {
String factoryClassName = factoryClass.getName();
try {
Enumeration urls = classLoader != null?classLoader.getResources("META-INF/spring.factories"):ClassLoader.getSystemResources("META-INF/spring.factories");
ArrayList result = new ArrayList();
while(urls.hasMoreElements()) {
URL url = (URL)urls.nextElement();
Properties properties = PropertiesLoaderUtils.loadProperties(new UrlResource(url));
String factoryClassNames = properties.getProperty(factoryClassName);//加载所有工厂
result.addAll(Arrays.asList(StringUtils.commaDelimitedListToStringArray(factoryClassNames)));
}
return result;
} catch (IOException var8) {
throw new IllegalArgumentException("Unable to load [" + factoryClass.getName() + "] factories from location [" + "META-INF/spring.factories" + "]", var8);
}
}
这些工厂对应实现了不同的工厂类
private Collection getSpringFactoriesInstances(Class type, Class[] parameterTypes, Object... args) {
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
Set names = new LinkedHashSet(SpringFactoriesLoader.loadFactoryNames(type, classLoader));
List instances = this.createSpringFactoriesInstances(type, parameterTypes, classLoader, args, names);
AnnotationAwareOrderComparator.sort(instances);
return instances;
}
* e.g 需要实例化的工厂
实例化所有工厂并排序
private void initialize(Object[] sources) {
if(sources != null && sources.length > 0) {
this.sources.addAll(Arrays.asList(sources));
}
this.webEnvironment = this.deduceWebEnvironment();
this.setInitializers(this.getSpringFactoriesInstances(ApplicationContextInitializer.class));
this.setListeners(this.getSpringFactoriesInstances(ApplicationListener.class));
this.mainApplicationClass = this.deduceMainApplicationClass();
}
接下来为每个工厂设置监听
private Class deduceMainApplicationClass() {
try {
StackTraceElement[] stackTrace = (new RuntimeException()).getStackTrace();
StackTraceElement[] var2 = stackTrace;
int var3 = stackTrace.length;
for(int var4 = 0; var4 < var3; ++var4) {
StackTraceElement stackTraceElement = var2[var4];
if("main".equals(stackTraceElement.getMethodName())) {
return Class.forName(stackTraceElement.getClassName());
}
}
} catch (ClassNotFoundException var6) {
;
}
return null;
}
设置异常处理栈
SpringApplication设置并初始化完毕,接下来看下它的run方法
public ConfigurableApplicationContext run(String... args) {
StopWatch stopWatch = new StopWatch();
stopWatch.start();
ConfigurableApplicationContext context = null;
FailureAnalyzers analyzers = null;
this.configureHeadlessProperty();
SpringApplicationRunListeners listeners = this.getRunListeners(args);//加载刚才所有 //SpringApplicationRunListener listener实例并启动
listeners.starting();
try {
ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
ConfigurableEnvironment environment = this.prepareEnvironment(listeners, applicationArguments);
Banner printedBanner = this.printBanner(environment);
context = this.createApplicationContext();
new FailureAnalyzers(context);
this.prepareContext(context, environment, listeners, applicationArguments, printedBanner);
this.refreshContext(context);
this.afterRefresh(context, applicationArguments);
listeners.finished(context, (Throwable)null);
stopWatch.stop();
if(this.logStartupInfo) {
(new StartupInfoLogger(this.mainApplicationClass)).logStarted(this.getApplicationLog(), stopWatch);
}
return context;
} catch (Throwable var9) {
this.handleRunFailure(context, listeners, (FailureAnalyzers)analyzers, var9);
throw new IllegalStateException(var9);
}
}
看下listener.start方法在干什么:
依次执行以上构造方法
public void starting() {
this.initialMulticaster.multicastEvent(new ApplicationStartedEvent(this.application, this.args));
}
public void multicastEvent(ApplicationEvent event) {
this.multicastEvent(event, this.resolveDefaultEventType(event));
}
遍历所有观察者,发布事件
public void multicastEvent(final ApplicationEvent event, ResolvableType eventType) {
ResolvableType type = eventType != null?eventType:this.resolveDefaultEventType(event);
Iterator var4 = this.getApplicationListeners(event, type).iterator();
while(var4.hasNext()) {
final ApplicationListener listener = (ApplicationListener)var4.next();
Executor executor = this.getTaskExecutor();
if(executor != null) {
executor.execute(new Runnable() {
public void run() {
SimpleApplicationEventMulticaster.this.invokeListener(listener, event);
}
});
} else {
this.invokeListener(listener, event);
}
}
}
//发布事件,spring启动啦,各部门该干啥干啥去啦
protected void invokeListener(ApplicationListener listener, ApplicationEvent event) {
ErrorHandler errorHandler = this.getErrorHandler();
if(errorHandler != null) {
try {
listener.onApplicationEvent(event);
} catch (Throwable var7) {
errorHandler.handleError(var7);
}
} else {
try {
listener.onApplicationEvent(event);
} catch (ClassCastException var8) {
String msg = var8.getMessage();
if(msg != null && !msg.startsWith(event.getClass().getName())) {
throw var8;
}
Log logger = LogFactory.getLog(this.getClass());
if(logger.isDebugEnabled()) {
logger.debug("Non-matching event type for listener: " + listener, var8);
}
}
}
}
//接着发布spring准备好了启动事件
ConfigurableEnvironment environment = this.prepareEnvironment(listeners, applicationArguments);
//打印logo,初始化各个上下文
context = this.createApplicationContext();
new FailureAnalyzers(context);
this.prepareContext(context, environment, listeners, applicationArguments, printedBanner);
this.refreshContext(context);
this.afterRefresh(context, applicationArguments);
listeners.finished(context, (Throwable)null);
stopWatch.stop();
//stopWatch监听启动用时
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