spring占位符解析器---PropertyPlaceholderHelper

一、PropertyPlaceholderHelper 职责

　　扮演者占位符解析器的角色,专门用来负责解析路劲中or名字中的占位符的字符，并替换上具体的值

二、例子

public class PropertyPlaceholderHelperDemo {

    @SuppressWarnings("resource")
    public static void main(String[] args) {
        Properties properties = System.getProperties();
        
        properties.setProperty("prefixName", "read-code");
        
        ApplicationContext ac = new ClassPathXmlApplicationContext("classpath:${prefixName}-spring.xml");
        
        ReadCodeService readCodeService = (ReadCodeService) ac.getBean("readCodeService");
        
        readCodeService.say();
    }
}

你可以debug进去，看下源码。底层PropertyPlaceholderHelper会去解析替换占位符value。