Including External Image in JSP

Question

Hi all,
I need to be able to load a external image (image in a specific loaction on the server but not in the webapp location). Unfortunealty I cannot use servlets and have to code it in the JSP directly.
So far I have this code :
<%@ page import="java.io.*"%>
<%@ page import="javax.imageio.stream.*"%>
<%@ page import="br.gov.sc.tce.sco.view.framework.Constants"%>
<%
     response.setContentType("image/gif");
     String  fileName = Constants.UPLOAD_FOTO_HOME + ( request.getParameter("fileName") == null ? "" : request.getParameter("fileName") );
     FileInputStream fis = null;
     OutputStream os = null;
     try {
          fis = new FileInputStream(fileName);
          os = response.getOutputStream();
          while ( fis.available() > 0  ) {
               os.write(fis.read());
     } catch (Exception e) {
          e.printStackTrace();
     } finally {
          if (fis != null) {
               try {fis.close();} catch (IOException e1) {} finally {fis = null;}
          if (os != null) {
               try {os.flush();os.close();} catch (IOException e1) {} finally {os = null;}
%>and in the pages that need to include pages I do something like the following :
<img src="<%=appName%>/include/jsp/showImage.jsp?fileName=<%=((Foto)fotoCad).getNomeArquivo()%>" width="60" height="60">This all seems to work ok , the images display , except that I get a stacktrace error afterwards of java.lang.IllegalStateException: getOutputStream() has already been called for this response
Any help would be appreciated
Regards
Robin

Answer 1

If you want to get rid of the exception, you have to remove all carriage returns between your JSP tags
Explanation:
If you put a carriage return in your code, the generated servlet generates: out.println("\r\n") (depending on your os)
In other words it has already got the output stream/writer in order to print out some characters to the stream. Hence the generated error message.
The following should generate without any exception raised.
See how carriage returns are eliminated?
Note this also includes no carriage return at the END of the file after the closing %>
<%@ page import="java.io.*"
%><%@ page import="javax.imageio.stream.*"
%><%@ page import="br.gov.sc.tce.sco.view.framework.Constants"
%><%@ page contentType="image/gif" %><%
     String  fileName = Constants.UPLOAD_FOTO_HOME + ( request.getParameter("fileName") == null ? "" : request.getParameter("fileName") );
     FileInputStream fis = null;
     OutputStream os = null;
     try {
          fis = new FileInputStream(fileName);
          os = response.getOutputStream();
          while ( fis.available() > 0  ) {
               os.write(fis.read());
     } catch (Exception e) {
          e.printStackTrace(System.out);
     } finally {
          if (fis != null) {
               try {fis.close();} catch (IOException e1) {} finally {fis = null;}
          if (os != null) {
               try {os.flush();os.close();} catch (IOException e1) {} finally {os = null;}
%>