页面发生500错误

org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'com/imooc/sm/dao/DepartmentDao.xml'. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias ' String'.  Cause: java.lang.ClassNotFoundException: Cannot find class:  String

网页错误是

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'departmentController': Unsatisfied dependency expressed through field 'departmentService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'departmentService': Unsatisfied dependency expressed through field 'departmentDao'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'departmentDao' defined in URL [jar:file:/D:/apache-tomcat-8.5.39/webapps/ROOT/WEB-INF/lib/sm_service-1.0-SNAPSHOT.jar!/com/imooc/sm/dao/DepartmentDao.class]: Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'com/imooc/sm/dao/DepartmentDao.xml'. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias ' String'.  Cause: java.lang.ClassNotFoundException: Cannot find class:  String