Read data from the background to <s:select> in Struts2

See online a lot of struts2 from the background to read data to <s:select>, but are not too detailed, may be I can not understand it! So I made a myself, which may have a lot of bad places, look at the vast number of netizens pointed out

Results

 Public classBooksImplementsjava.io.Serializable {// Fields    PrivateString bookId; PrivateString BookType; PrivateString BookName; PrivateString Bookauthor; PrivateString bookpress; PrivateFloat Bookprice; PrivateInteger Booknumber; PrivateSet readers =NewHashSet ();//omit the corresponding set and get methods}

In Impl

// query all book types     Public List Findbooktype ()    {        = hibernatesessionfactory.getsession ();         = session.begintransaction ();        String hql= "from Books GROUP by BookType";         = Session.createquery (hql);         = query.list ();         return list;    }

In action

 Publicstring Findbooktype () {string result= "Error"; List List=NULL; Booksdao Booksdao=NewBooksimpl (); List=Booksdao.findbooktype (); if(list!=NULL) {Actioncontext CTX=Actioncontext.getcontext (); Map Map=ctx.getsession (); Map.put ("BookType", list); //result= "error";SYSTEM.OUT.PRINTLN ("--->" +list.size ()); }                    returnresult; }

In JSP

<label= "category"  name= "Books.booktype"  list= "# Session.booktype "                            listKey=" id "  listvalue=" BookType "  Headerkey= "-1"  headervalue= "Please select the category of the book"                            emptyoption= " False "/>

Struts2 reads data from the background to <s:select>