Spring boot Could not resolve placeholder

在resources目录下配置了application.properties文件，其中：
spring.data.mongodb.uri=mongodb://

每次启动时，都会报错：
Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'spring.data.mongodb.uri' in value "${spring.data.mongodb.uri}"

但是之前是可以启动的，代码片段：
@Configuration
public class MongoDataSourceConfiguration {
@Value("${spring.data.mongodb.uri}")
private String uri;

...to do something...

}

请问如何解决呢？

 <context:property-placeholder location="classpath*:redis.properties" ignore-unresolvable="true" />  

看见后面ignore-unresolvable属性没？百度下这个属性估计你问题就解决了

http://blog.csdn.net/longerandlonger/article/details/7193160

加上这个