Issue
I'm trying to go to a jnlp file from a jsp page to get the fingerprints of users registered, the file is as below..
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%
String path = request.getContextPath();
String protocol = request.getScheme();
String domain = request.getServerName();
String port = Integer.toString(request.getServerPort());
String a = protocol + "://" + domain + ":" + port + path;
path = protocol + "://" + domain + ":" + port + path + "/";
%>
<%@page contentType="application/x-java-jnlp-file" pageEncoding="UTF-8"%>
<%@taglib uri="http://www.springframework.org/tags" prefix="spring" %>
<?xml version="1.0" encoding="UTF-8"?>
<jnlp spec="1.0+" codebase="<%=path%>" href="">
<information>
<title>Mytitle</title>
<vendor>Myvendor</vendor>
</information>
<security><all-permissions/></security>
<resources>
<!-- Application Resources -->
<j2se version="1.6+" href="http://java.sun.com/products/auto/j2se"/>
<jar href="jnlp/FingerPrintApplet.jar" main="true"/>
</resources>
<application-desc main-class="ui.InvitationApplet">
<argument>${firstName}</argument>
<argument>${lastName}</argument>
<argument>${loginId}</argument>
<argument>${roleId}</argument>
<argument>${urlCode}</argument>
<argument>${mainRecordOfficer}</argument>
<argument>${middleName}</argument>
<argument>${employeeId}</argument>
<argument>${createdBy}</argument>
<argument><%=a%></argument>
<argument>${invitedUnder}</argument>
<argument>${login_type}</argument>
</application-desc>
</jnlp>
But every time jsp page is hit, jnlp gets downloaded but I get exception
java.lang.IllegalStateException: getOutputStream() has already been called for this response
I also came to know that this exception is due to "blank spaces" for new lines in the compiled jsp file, for that I also added below line at the top of jsp
<%@ page trimDirectiveWhitespaces="true" %>
But still I get same issue, and then I also did some stupid things like removing blank spaces in jsp file manually like
<%@ page .....%><%@ page.....%>
But still same exception.
Solution
This occurs because, white spaces are preserved by default in jsp page, which may get added to output as a line, so the above explained exception comes, to get rid of that just add following lines in web.xml
and this should be fixed.
<jsp-config>
<jsp-property-group>
<url-pattern>*.jsp</url-pattern>
<trim-directive-whitespaces>true</trim-directive-whitespaces>
</jsp-property-group>
</jsp-config>
Answered By - Mithilesh Tipkari