Spring data JPA只查询部分字段问题及解决

@sqlresultsetmapping(name = "ebookinfo",
        classes = @constructorresult(targetclass = ebookinfo.class,
                columns = {
                        @columnresult(name = "book_id", type = long.class),
                        @columnresult(name = "book_name", type = string.class),
                        @columnresult(name = "file_type", type = string.class)
                }))
@namednativequery(name = "listexpressebooks",
        query = "select book_id, book_name, file_type from ebook order by update_date desc",
        resultsetmapping = "ebookinfo")
@entity
@table(name = "ebook")
public class ebook {

    private long bookid;

    private integer authorid;
    private string authorname;
    private integer categoryid;
    private string bookname;
    private string subtitle;
    private string tags;
    private string isbn;
    private string edition;
    private byte booktype;
    private integer star;
    private integer downloadcount;
    private byte status;
    private string filetype;
    private string outline;
    private string introduction;
    private string preface;
    private string cover;
    private float price;
    private string publisher;
    private string bgcolor;
    private string forecolor;
    private string titlecolor;
    private string coverbackgroundid;
    private string coverpictureid;
    private integer covertemplateid;
    private string coverpicturemode;
    private integer pagemode;
    private timestamp requestdate;
    private timestamp publishdate;
    private timestamp updatedate;

@data
public class ebookinfo {
    private long bookid;
    private string bookname;    
    private string filetype;

    public ebookinfo(long bookid, string bookname, string filetype) {
        this.bookid = bookid;
        this.bookname = bookname;
        this.filetype = filetype;
    }

}

    @query(name = "listexpressebooks", nativequery = true)
    public list<ebookinfo> listexpressebooks();

public list<blog> selectbyyearmonth(string year, string month, int status) {
    string sql = string.format("select new blog(blog.id, blog.title, blog.abs, blog.createtime) from blog blog where blog.status = %d and year(createtime) = %s and month(createtime) = %s order by blog.createtime desc", status, year, month);

    //query query = this.em.createnativequery(sql, "expressedresult");
    query query = this.em.createquery(sql);
    list results = query.getresultlist();

    return results;
}

class nativeresultprocessutils {

        /**
         * tuple转实体对象
         * @param source tuple对象
         * @param targetclass 目标实体class
         * @param <t> 目标实体类型
         * @return 目标实体
         */
        public static <t> t processresult(tuple source,class<t> targetclass) {
            object instantiate = beanutils.instantiate(targetclass);
            converttupletobean(source,instantiate,null);
            return (t) instantiate;
        }

        /**
         *
         * tuple转实体对象
         * @param source tuple对象
         * @param targetclass 目标实体class
         * @param <t> 目标实体类型
         * @param ignoreproperties 要忽略的属性
         * @return 目标实体
         */
        public static <t> t processresult(tuple source,class<t> targetclass,string... ignoreproperties) {
            object instantiate = beanutils.instantiate(targetclass);
            converttupletobean(source,instantiate,ignoreproperties);
            return (t) instantiate;
        }

        /**
         * 把tuple中属性名相同的值复制到实体中
         * @param source tuple对象
         * @param target 目标对象实例
         */
        public static void converttupletobean(tuple source,object target){
            converttupletobean(source,target,null);
        }

        /**
         * 把tuple中属性名相同的值复制到实体中
         * @param source tuple对象
         * @param target 目标对象实例
         * @param ignoreproperties 要忽略的属性
         */
        public static void converttupletobean(tuple source,object target, string... ignoreproperties){
            //目标class
            class<?> actualeditable = target.getclass();
            //获取目标类的属性信息
            propertydescriptor[] targetpds = beanutils.getpropertydescriptors(actualeditable);
            //忽略列表
            list<string> ignorelist = (ignoreproperties != null ? arrays.aslist(ignoreproperties) : null);

            //遍历属性节点信息
            for (propertydescriptor targetpd : targetpds) {
                //获取set方法
                method writemethod = targetpd.getwritemethod();
                //判断字段是否可以set
                if (writemethod != null && (ignorelist == null || !ignorelist.contains(targetpd.getname()))) {
                    //获取source节点对应的属性
                    string propertyname = targetpd.getname();
                    object value = source.get(propertyname);
                    if(value!=null && classutils.isassignable(writemethod.getparametertypes()[0], value.getclass())) {
                        try {
                            //判断target属性是否private
                            if (!modifier.ispublic(writemethod.getdeclaringclass().getmodifiers())) {
                                writemethod.setaccessible(true);
                            }
                            //写入target
                            writemethod.invoke(target, value);
                        }
                        catch (throwable ex) {
                            throw new fatalbeanexception(
                                "could not copy property '" + targetpd.getname() + "' from source to target", ex);
                        }
                    }
                }
            }
        }

    }