获取类上的注解的相关参数

Class clsEntity=Class.forName("com.controllon.modul." + entityName);

        if (clsEntity==null) {return 0;}        Field tableColumn = clsEntity.getDeclaredField(column);        if (tableColumn==null) {return 0;}        javax.persistence.Column columnAnnotation = (Column) tableColumn.getAnnotation(Column.class);        int len = 0 ;               if (columnAnnotation==null) {             // 获取默认的长度        } else {            len = columnAnnotation.length() ;        }