Failed to convert property value of type [java.lang.String] to required type [int]

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [applicationContext.xml]: Initialization of bean failed; nested exception is org.springframework.beans.TypeMismatchException: Failed to convert property value of type [java.lang.String] to required type [int] for property 'initialPoolSize'; nested exception is java.lang.NumberFormatException: For input string: "${jdbc.initPoolSize}"

Caused by: org.springframework.beans.TypeMismatchException: Failed to convert property value of type [java.lang.String] to required type [int] for property 'initialPoolSize'; nested exception is java.lang.NumberFormatException: For input string: "${jdbc.initPoolSize}"

Caused by: java.lang.NumberFormatException: For input string: "${jdbc.initPoolSize}"

Spring开发时遇到这个错误，先以为是类型转换出了问题，可是检查不出毛病，最后才发现并不是类型转换的问题，而是我资源 配置文件没有导入得到Spring配置中

先在Spring配置文件中添加

然后在配置文件中添加导入代码

classpath:db.properties：资源文件路径