Spring源码:initMessageSource源码解析
针对于国际化问题的MessageSource
/**
* Initialize the MessageSource.
* Use parent's if none defined in this context.
*/
protected void initMessageSource() {
//获取Bean工厂,一般是DefaultListBeanFactory
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
//首先判断是否已有xml文件定义了id为messageSource的bean对象
if (beanFactory.containsLocalBean(MESSAGE_SOURCE_BEAN_NAME)) {
//如果有,则从Bean工厂得到这个bean对象
this.messageSource = beanFactory.getBean(MESSAGE_SOURCE_BEAN_NAME, MessageSource.class);
// Make MessageSource aware of parent MessageSource.
//当父类Bean工厂不为空,并且这个bean对象是HierarchicalMessageSource类型
if (this.parent != null && this.messageSource instanceof HierarchicalMessageSource) {
//为HierarchicalMessageSource的实现类
HierarchicalMessageSource hms = (HierarchicalMessageSource) this.messageSource;
//设置父类MessageSource,此处设置内部的parent messageSource
if (hms.getParentMessageSource() == null) {
// Only set parent context as parent MessageSource if no parent MessageSource
// registered already.
hms.setParentMessageSource(getInternalParentMessageSource());
}
}
if (logger.isTraceEnabled()) {
logger.trace("Using MessageSource [" + this.messageSource + "]");
}
}
else {
// Use empty MessageSource to be able to accept getMessage calls.
//如果没有xml文件定义信息源对象,新建DelegatingMessageSource类作为messageSource的Bean
//因为DelegatingMessageSource类实现了HierarchicalMessageSource接口,而这个接口继承了MessageSource这个类
//因此实现了这个接口的类,都是MessageSource的子类,因此DelegatingMessageSource也是一个MessageSource
DelegatingMessageSource dms = new DelegatingMessageSource();
//给这个DelegatingMessageSource添加父类消息源
dms.setParentMessageSource(getInternalParentMessageSource());
this.messageSource = dms;
//将这个messageSource实例注册到Bean工厂中
beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource);
if (logger.isTraceEnabled()) {
logger.trace("No '" + MESSAGE_SOURCE_BEAN_NAME + "' bean, using [" + this.messageSource + "]");
}
}
}