AbstractRefreshableConfigApplicationContext

/**
* Resolve the given path, replacing placeholders with corresponding
* system property values if necessary. Applied to config locations.
* @param path the original file path
* @return the resolved file path
* @see org.springframework.util.SystemPropertyUtils#resolvePlaceholders
*/

用系统定义的值，比如: 类路径替换 "java.class.path"

resolvePath(String path)