ApplicationContext(九)初始化非延遲的 bean
阿新 • • 發佈:2019-02-23
ble rename sla factory parse frame root ora allow
ApplicationContext(九)初始化非延遲的 bean
此至,ApplicationContext 已經完成了全部的準備工作,開始初始化剩余的 bean 了(第 11 步)。
public void refresh() throws BeansException, IllegalStateException {
// 11. 初始化剩余的 bean (部分在 invokeBeanFactoryPostProcessors 已經初始化)
finishBeanFactoryInitialization(beanFactory);
}
finishBeanFactoryInitialization 主要是實例化非懶加載的 bean。
protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) { // 1. 註冊 ConversionService,註意 beanName 必須為 conversionService if (beanFactory.containsBean(CONVERSION_SERVICE_BEAN_NAME) && beanFactory.isTypeMatch(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class)) { beanFactory.setConversionService( beanFactory.getBean(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class)); } // Initialize LoadTimeWeaverAware beans early to allow for registering their transformers early. String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false); for (String weaverAwareName : weaverAwareNames) { getBean(weaverAwareName); } // Stop using the temporary ClassLoader for type matching. beanFactory.setTempClassLoader(null); // 2. 凍結所有的 bean 定義,說明註冊的 bean 定義將不被修改 beanFactory.freezeConfiguration(); // 3. 初始化剩下的 bean beanFactory.preInstantiateSingletons(); }
一、註冊 ConversionService
(1) String2DateConverter
public class String2DateConverter implements Converter<String, Date> { @Override public Date convert(String source) { SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd"); try { return sdf.parse(source); } catch (ParseException e) { ; } return null; } }
(2) 註冊
註意:beanName 必須為 conversionService
<bean id="conversionService" class="org.springframework.context.support.ConversionServiceFactoryBean">
<property name="converters">
<set>
<bean class="com.github.binarylei.spring01.day0728.conversionservice.String2DateConverter"/>
</set>
</property>
</bean>
(3) 測試
@Test
public void test() {
DefaultConversionService service = new DefaultConversionService();
service.addConverter(new String2DateConverter());
Date value = service.convert("2018-08-02", Date.class);
System.out.println(value);
}
二、凍結配置
源代碼【DefaultListableBeanFactory】
public void freezeConfiguration() {
this.configurationFrozen = true;
this.frozenBeanDefinitionNames = StringUtils.toStringArray(this.beanDefinitionNames);
}
三、初始化非延遲加載
public void preInstantiateSingletons() throws BeansException {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Pre-instantiating singletons in " + this);
}
// 1. 創建剩下的單實例 bean
List<String> beanNames = new ArrayList<String>(this.beanDefinitionNames);
// Trigger initialization of all non-lazy singleton beans...
for (String beanName : beanNames) {
RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
if (isFactoryBean(beanName)) {
final FactoryBean<?> factory = (FactoryBean<?>) getBean(FACTORY_BEAN_PREFIX + beanName);
boolean isEagerInit;
if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) {
isEagerInit = AccessController.doPrivileged(new PrivilegedAction<Boolean>() {
@Override
public Boolean run() {
return ((SmartFactoryBean<?>) factory).isEagerInit();
}
}, getAccessControlContext());
}
else {
isEagerInit = (factory instanceof SmartFactoryBean &&
((SmartFactoryBean<?>) factory).isEagerInit());
}
if (isEagerInit) {
getBean(beanName);
}
}
else {
getBean(beanName);
}
}
}
// 2. 篩選出實現了 SmartInitializingSingleton 接口的 bean,回調 afterSingletonsInstantiated() 方法
// @EventListener 註解的方式註冊監聽器就是在這一步完成的
for (String beanName : beanNames) {
Object singletonInstance = getSingleton(beanName);
if (singletonInstance instanceof SmartInitializingSingleton) {
final SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance;
if (System.getSecurityManager() != null) {
AccessController.doPrivileged(new PrivilegedAction<Object>() {
@Override
public Object run() {
smartSingleton.afterSingletonsInstantiated();
return null;
}
}, getAccessControlContext());
}
else {
smartSingleton.afterSingletonsInstantiated();
}
}
}
}
每天用心記錄一點點。內容也許不重要,但習慣很重要!
ApplicationContext(九)初始化非延遲的 bean