Render a JSP page into HTML in a String

I've figured a ver ugly workarround... Using HttpUtils to make a self http request in my application through Tomcat, get the HTML and store it in a String, but I obviously loose session and request information, of course, as I am creating a plain new request. Maybe I code this till I find something a bit more elegant.

Thanks,

Ignacio

icordobaa at 2007-7-12 23:58:55 >

The perfect example of how the mail gets triggered is the "Forgot my password mail". The user invokes a serlvet (a struts action in fact) that must generate an email, but return a complete different response to the user browser: ("Please check your mail"). The email is in HTML and I want it to be rendered from a JSP, which has nothiing to do with the response returned to the browser, but sharing the request (user info and other objects set as attributes to the response). I want to achieve this because my design department likes designing this emails directly as JSPs (somehow I have managed to make them learn some JSP) and with complete independence from my code. Thanks for your examples. I'll try to figure it out how to split response to the browser from response in the HttpServletResponseWrapper.

icordobaa at 2007-7-12 23:58:55 >

Hi again

any ideas on why this is not working?

I get an empty ByteArrayOutputStream / String (include() method in the dispatcher doesn't make the dispatcher write anything into the OutputStream).

templatePath is the absolute path of the JSP ("/user/ForgotPassword.jsp")

ByteArrayOutputStream out = new ByteArrayOutputStream();

RequestDispatcher dispatcher = servletcontext.getRequestDispatcher(templatePath);

RedirectingServletResponse dummyResponse = new RedirectingServletResponse(response, out);

dispatcher.include(request,dummyResponse);

return out.toString();

Thanks for any info.

icordobaa at 2007-7-12 23:58:55 >

[nobr]Ok, just tried it out myself, and I'm getting the same result you are.

Nothing makes it out to the RedirectingServletResponse.

It appears to be buffering it somewhere in the included page.

If you put a command to flush the buffer on the jsp page being included: <% out.flush; %> then it works.

So why doesn't it work normally? Why doesn't the call to requestDispatcher.include (or forward) flush/commit its response?

I will admit to being stuck on this one. I'm figuring its something in the internal workings of Tomcat/JSP to do with when a page is flushed or not, but I can't thing of anything right now.

Here is the test I put together to try this out (along with a few corrections to my previous code). I will admit to being stumped :-)

The response wrapper:

package web;

import java.io.IOException;

import java.io.OutputStream;

import java.io.PrintWriter;

import javax.servlet.ServletOutputStream;

import javax.servlet.ServletResponse;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpServletResponseWrapper;

public class RedirectingServletResponse extends HttpServletResponseWrapper {

RedirectServletStream out;

/**

* @param arg0

*/

public RedirectingServletResponse(HttpServletResponse response, OutputStream out) {

super(response);

this.out = new RedirectServletStream(out);

}

/* (non-Javadoc)

* @see javax.servlet.ServletResponse#flushBuffer()

*/

public void flushBuffer() throws IOException {

out.flush();

}

/* (non-Javadoc)

* @see javax.servlet.ServletResponse#getOutputStream()

*/

public ServletOutputStream getOutputStream() throws IOException {

return out;

}

/* (non-Javadoc)

* @see javax.servlet.ServletResponse#getWriter()

*/

public PrintWriter getWriter() throws IOException {

return new PrintWriter(out);

}

/* (non-Javadoc)

* @see javax.servlet.ServletResponseWrapper#getResponse()

*/

public ServletResponse getResponse() {

return super.getResponse();

}

/* (non-Javadoc)

* @see javax.servlet.ServletResponseWrapper#setResponse(javax.servlet.ServletResponse)

*/

public void setResponse(ServletResponse arg0) {

super.setResponse(arg0);

}

private static class RedirectServletStream extends ServletOutputStream {

OutputStream out;

RedirectServletStream(OutputStream out) {

this.out = out;

}

public void write(int param) throws java.io.IOException {

out.write(param);

}

}

}

A JSP using this class: requestWrapperTest.jsp

<%@ page import="java.io.*" %>

<%@ page import="web.RedirectingServletResponse" %>

<%@ page contentType="text/html;charset=UTF8" %>

<%!

public String getEmailText(HttpServletRequest request, HttpServletResponse response, String emailURL) {

try{

// create an output stream - to file, to memory...

ByteArrayOutputStream out = new ByteArrayOutputStream();

// create the "dummy" response object

RedirectingServletResponse dummyResponse;

dummyResponse = new RedirectingServletResponse(response, out);

// get a request dispatcher for the email template to load

RequestDispatcher rd = request.getRequestDispatcher(emailURL);

// execute that JSP

rd.include(request, dummyResponse);

// at this point the ByteArrayOutputStream has had the response written into it.

dummyResponse.flushBuffer();

byte[] result = out.toByteArray();

System.out.println("result = " + result.length);

// now you can do with it what you will.

String emailText = new String(result);

return emailText;

}

catch (Exception e){

e.printStackTrace(System.out);

return "DANGER WILL ROBINSON!";

}

}

%>

<html>

<body>

<h2> Server Info Virtual!!</h2>

Server info = <%= application.getServerInfo() %> <br>

Servlet engine version = <%= application.getMajorVersion() %>.<%= application.getMinorVersion() %><br>

Java version = <%= System.getProperty("java.vm.version") %><br>

<hr>

<%

String result = getEmailText(request, response, "/testLoad.jsp");

System.out.println(result);

%>

<%= result %>

</body>

</html>

And the template page being included: testLoad.jsp

This is the page loaded for testing

<%

System.out.println("in the inner jsp");

// uncomment the following line to see this example work

//out.flush();

%>

[/nobr]

evnafetsa at 2007-7-12 23:58:56 >