使用ssh框架开发web应用出现以下错误

Unable to instantiate Action, printAction, defined for 'provider' in namespace '/system'Error creating bean with name 'printAction' defined in class path resource [spring/struts/system.xml]: Error setting property values; nested exception is org.springframework.beans.NotWritablePropertyException: Invalid property 'printService' of bean class [com.dbwen.system.web.action.PrintAction]: Bean property 'printService' is not writable or has an invalid setter method. Does the parameter type of the setter match the return type of the getter?