How to display images and information

Question

how to display images and information(e.g. like questions) on a jsp page that stored in a database

Answer 1

Look As far as i can see....
Utlimately every file could be expressed as a bytes buffer.
so say if you have a bean called Choice Bean which is expressed as
public class ChoiceBean{
   private String choiceid;
   private String choicedesc;
   private byte image[];
   public void setChoiceId(String choiceid){
          this.choiceid = choiceid;
    public String getChoiceId(){
           return this.choiceid;
      public void setChoiceDesc(String choicedesc){
           this.choicedesc = choicedesc;
       public String getChoiceDesc(){
           return this.choicedesc;
       public void setImage(byte image[]){
              this.image = image;
         public byte[] getImage(){
              return this.image;
}QuestionList.java:
===============
public class QuestionList{
     private List<ChoiceBean> choicelist;
      /*Other member variable declarations*/
       public  List<ChoiceBean> getChoiceList(){
                /*Custom code where you may build the list by querying the DA layer*/
                 return this.choicelist;
     public int search(String choiceid){
             int index = -1;
             for(int i =0 ; i < this.choicelist.size() ; i++){
                    ChoiceBean cb = this.choicelist.get(i);
                     if(cb.getChoiceId().equals(choiceid)){
                            index = i;
                            break;
             return index;
    /* Other member method declarations */
}and you are retreving List<ChoiceBean> from DB using your query & have created a session attribute / <jsp:useBean> named ChoiceList
NOTE: sometimes your application server can go out of bounds as you are consuming a lot of memory by creating an arraylist object.
use the following methodology to display images & choices
sample.jsp:
=========
<jsp:useBean id="QuestionList"  class="com.qpa.dao.QuestionList" scope="session"/>
<TABLE>
<%
/* QuestionList.getChoiceList() is a method which fetches data from the DB & returns it in form of  List<ChoiceBean> */
List<ChoiceBean> choicelist = QuestionList.getChoiceList();
for(int i =0 ; i < choicelist.size() ; i++){
%>
<TR>
<TD><%!=choicelist.get(i).getChoiceId()%></TD>
<!-- calling servlet which renders an images in JPG format based upon given choiceid(unique field) -->
<TD><IMAGE src="ImageServlet?choiceid=<%!=choicelist.get(i).getChoiceId()%>"/> </TD>
<TD><%!=choicelist.get(i).getChoiceDesc()%></TD>
</TR>
<%
%>
</TABLE>
<%
    session.remove("QuestionList");
%>
NOTE: usage of JSTL or any other custom built tag-libraries makes life more simpler in the following case
ImageServlet.java:
===============
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        byte buffer[] = null;
        HttpSession session = request.getSession(false);
        /*getting the QuestionList from the session*/
        QuestionList ql = null;
        String choiceid = new String("");
        try{
             choiceid = request.getParameter("choiceid");
             /*getting the QuestionList from the session*/
            ql = (QuestionList)  session.getAttribute("QuestionList");
        } catch(Exception exp){
        if(choiceid.equals("") == false &&  ql != null ){
            List<ChoiceBean> clist = QuestionList.getChoiceList();           
               assuming that you have created a serach method which searches the entire choice list and would give you
               the index of that object which is being refered by unique choiceid and returns -1 if not found
            int index =  QuestionList.search(choiceid);
            if(index != -1){
               ChoiceBean cb = clist.get(index);
               buffer = cb.getImage();
        if(buffer != null){
             // assuming that we have stored images in JPEG format only
             JPEGImageDecoder decoder = JPEGCodec.createJPEGDecoder(new ByteArrayInputStream(buffer));
             BufferedImage image =decoder.decodeAsBufferedImage();
             response.setContentType("image/jpeg");
             // Send back image
             ServletOutputStream sos = response.getOutputStream();
             JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(sos);
             encoder.encode(image);
        } else {
           response.setContentType("text/html");
           response.getWriter().println("<b>Image data not found</b>");              
}However,i still feel there are few loopholes with this approach where Application Server can eat up a lot of heap space which may result in outofmemorybound exception.
Hope this might help :)
REGARDS,
RaHuL