BeanDefinitionVisitor, 遍历bean的各个属性用properties填充, BeanDefinitionVisitor会将替换的操作委托给内部的一个StringValueResolver来执行(PlaceholderResolvingStringValueResolver), 而这个StringValueResolver又会将操作委托给PropertyPlaceholderHelper, 这个helper(PropertyPlaceholderHelper)在实际执行的时候会执行内部的parseStringValue函数
使用BeanDefinitionVisitor的visitBeanDefinition方法来解析
···
protected void doProcessProperties(ConfigurableListableBeanFactory beanFactoryToProcess,
StringValueResolver valueResolver) {
BeanDefinitionVisitor visitor = new BeanDefinitionVisitor(valueResolver);
String[] beanNames = beanFactoryToProcess.getBeanDefinitionNames();
for (String curName : beanNames) {
// Check that we're not parsing our own bean definition,
// to avoid failing on unresolvable placeholders in properties file locations.
if (!(curName.equals(this.beanName) && beanFactoryToProcess.equals(this.beanFactory))) {
BeanDefinition bd = beanFactoryToProcess.getBeanDefinition(curName);
try {
visitor.visitBeanDefinition(bd);
}
catch (Exception ex) {
throw new BeanDefinitionStoreException(bd.getResourceDescription(), curName, ex.getMessage(), ex);
}
}
}
// New in Spring 2.5: resolve placeholders in alias target names and aliases as well.
beanFactoryToProcess.resolveAliases(valueResolver);
// New in Spring 3.0: resolve placeholders in embedded values such as annotation attributes.
beanFactoryToProcess.addEmbeddedValueResolver(valueResolver);
}
···
解析之后BeanDefinition的占位符将会被替换掉
