在上篇文章中SpringApplication到底run了什么（上）中，我們分析了下面這個run方法的前半部分，本篇文章繼續開工
public ConfigurableApplicationContext run(String... args) {
//。。。
//接上文繼續
configureIgnoreBeanInfo(environment);
Banner printedBanner = printBanner(environment);
context = createApplicationContext();
exceptionReporters = getSpringFactoriesInstances(
SpringBootExceptionReporter.class,
new Class[] { ConfigurableApplicationContext.class }, context);
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);
}
catch (Throwable ex) {
handleRunFailure(context, listeners, exceptionReporters, ex);
throw new IllegalStateException(ex);
}
listeners.running(context);
return context;
}
- 獲取系統屬性
spring.beaninfo.ignore
private void configureIgnoreBeanInfo(ConfigurableEnvironment environment) {
if (System.getProperty(
CachedIntrospectionResults."spring.beaninfo.ignore") == null) {
Boolean ignore = environment.getProperty("spring.beaninfo.ignore",
Boolean.class, Boolean.TRUE);
System.setProperty(CachedIntrospectionResults."spring.beaninfo.ignore",
ignore.toString());
}
}
但是這個屬性的作用還真不知道。。
- 打印banner
- 根據當前環境創建ApplicationContext
protected ConfigurableApplicationContext createApplicationContext() {
Class<?> contextClass = this.applicationContextClass;
if (contextClass == null) {
try {
switch (this.webApplicationType) {
case SERVLET:
contextClass = Class.forName(DEFAULT_WEB_CONTEXT_CLASS);
break;
case REACTIVE:
contextClass = Class.forName(DEFAULT_REACTIVE_WEB_CONTEXT_CLASS);
break;
default:
contextClass = Class.forName(DEFAULT_CONTEXT_CLASS);
}
}
catch (ClassNotFoundException ex) {
throw new IllegalStateException(
"Unable create a default ApplicationContext, "
+ "please specify an ApplicationContextClass",
ex);
}
}
return (ConfigurableApplicationContext) BeanUtils.instantiateClass(contextClass);
}
基於咱們的Servlet環境，所以創建的ApplicationContext為AnnotationConfigServletWebServerApplicationContext
9. 加載SpringBootExceptionReporter，這個類里包含了SpringBoot啟動失敗后異常處理相關的組件
private <T> Collection<T> getSpringFactoriesInstances(Class<T> type,
Class<?>[] parameterTypes, Object... args) {
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
Set<String> names = new LinkedHashSet<>(
SpringFactoriesLoader.loadFactoryNames(type, classLoader));
List<T> instances = createSpringFactoriesInstances(type, parameterTypes,
classLoader, args, names);
AnnotationAwareOrderComparator.sort(instances);
return instances;
}
10 prepareContext 這一塊還是比較長的
private void prepareContext(ConfigurableApplicationContext context,
ConfigurableEnvironment environment, SpringApplicationRunListeners listeners,
ApplicationArguments applicationArguments, Banner printedBanner) {
context.setEnvironment(environment);
postProcessApplicationContext(context);
applyInitializers(context);
listeners.contextPrepared(context);
if (this.logStartupInfo) {
logStartupInfo(context.getParent() == null);
logStartupProfileInfo(context);
}
context.getBeanFactory().registerSingleton("springApplicationArguments",
applicationArguments);
if (printedBanner != null) {
context.getBeanFactory().registerSingleton("springBootBanner", printedBanner);
}
// Load the sources
Set<Object> sources = getAllSources();
Assert.notEmpty(sources, "Sources must not be empty");
load(context, sources.toArray(new Object[0]));
listeners.contextLoaded(context);
}
1. 第一行，將context中相關的environment全部替換
public void setEnvironment(ConfigurableEnvironment environment) {
super.setEnvironment(environment); // 設置context的environment
this.reader.setEnvironment(environment); // 實例化context的reader屬性的conditionEvaluator屬性
this.scanner.setEnvironment(environment); // 設置context的scanner屬性的environment屬性
}
2. 上下文后處理
protected void postProcessApplicationContext(ConfigurableApplicationContext context) {
if (this.beanNameGenerator != null) {
context.getBeanFactory().registerSingleton(
AnnotationConfigUtils.CONFIGURATION_BEAN_NAME_GENERATOR,
this.beanNameGenerator);
}
if (this.resourceLoader != null) {
if (context instanceof GenericApplicationContext) {
((GenericApplicationContext) context)
.setResourceLoader(this.resourceLoader);
}
if (context instanceof DefaultResourceLoader) {
((DefaultResourceLoader) context)
.setClassLoader(this.resourceLoader.getClassLoader());
}
}
}
這一塊默認beanNameGenerator和resourceLoader都是空的，只有當我們自定義這兩個對象時才會把容器內的bean替換
3. 執行所有的ApplicationContextInitializer的initialize方法
protected void applyInitializers(ConfigurableApplicationContext context) {
for (ApplicationContextInitializer initializer : getInitializers()) {
Class<?> requiredType = GenericTypeResolver.resolveTypeArgument(
initializer.getClass(), ApplicationContextInitializer.class);
Assert.isInstanceOf(requiredType, context, "Unable to call initializer.");
initializer.initialize(context);
}
}
4. `listeners.contextPrepared(context)`這是個空方法，沒有實現，一個Spring的擴展點
5. 打印profile
6. 注冊bean：`springApplicationArguments`
7. 發布事件
public void contextLoaded(ConfigurableApplicationContext context) {
for (ApplicationListener<?> listener : this.application.getListeners()) {
if (listener instanceof ApplicationContextAware) {
((ApplicationContextAware) listener).setApplicationContext(context);
}
context.addApplicationListener(listener);
}
this.initialMulticaster.multicastEvent(
new ApplicationPreparedEvent(this.application, this.args, context));
}
這里不僅發布了ApplicationPreparedEvent事件，還往實現了ApplicationContextAware接口的監聽器中注入了context容器
8. load，其實就是創建了一個BeanDefinitionLoader對象
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);
}
loader.load();
}
- 容器的初始化
refreshContext
這個方法最后還是調用的AbstractApplicationContext類的refresh方法，由於篇幅過長這里就不展開了，感興趣的同學可以參考這篇文章：基於注解的SpringIOC源碼解析
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// 記錄容器的啟動時間、標記“已啟動”狀態、檢查環境變量
prepareRefresh();
// 初始化BeanFactory容器、注冊BeanDefinition
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// 設置 BeanFactory 的類加載器，添加幾個 BeanPostProcessor，手動注冊幾個特殊的 bean
prepareBeanFactory(beanFactory);
try {
// 擴展點
postProcessBeanFactory(beanFactory);
// 調用 BeanFactoryPostProcessor 各個實現類的 postProcessBeanFactory(factory) 方法
invokeBeanFactoryPostProcessors(beanFactory);
// 注冊 BeanPostProcessor 的實現類
registerBeanPostProcessors(beanFactory);
// 初始化MessageSource
initMessageSource();
// 初始化事件廣播器
initApplicationEventMulticaster();
// 擴展點
onRefresh();
// 注冊事件監聽器
registerListeners();
// 初始化所有的 singleton beans
finishBeanFactoryInitialization(beanFactory);
// 廣播事件
finishRefresh();
}
catch (BeansException ex) {
if (logger.isWarnEnabled()) {
logger.warn("Exception encountered during context initialization - " +
"cancelling refresh attempt: " + ex);
}
// 銷毀已經初始化的的Bean
destroyBeans();
// 設置 'active' 狀態
cancelRefresh(ex);
throw ex;
}
finally {
// 清除緩存
resetCommonCaches();
}
}
}
afterRefresh
這里沒有任何實現，Spring留給我們的擴展點- 停止之前啟動的計時裝置，然后發送
ApplicationStartedEvent事件 - 調用系統中
ApplicationRunner以及CommandLineRunner接口的實現類，關於這兩個接口的使用可以參考我的這篇文章：Java項目啟動時執行指定方法的幾種方式
private void callRunners(ApplicationContext context, ApplicationArguments args) {
List<Object> runners = new ArrayList<>();
runners.addAll(context.getBeansOfType(ApplicationRunner.class).values());
runners.addAll(context.getBeansOfType(CommandLineRunner.class).values());
AnnotationAwareOrderComparator.sort(runners);
for (Object runner : new LinkedHashSet<>(runners)) {
if (runner instanceof ApplicationRunner) {
callRunner((ApplicationRunner) runner, args);
}
if (runner instanceof CommandLineRunner) {
callRunner((CommandLineRunner) runner, args);
}
}
}
- 異常處理
- 發送
ApplicationReadyEvent事件