Navigation not possible until page is completely loaded -- Severe usability

The tag above is the culprit. It appears the facesservlet will only return the current page if it does not receive the hidden field.

I've written a filter as a work around (well more like copied someone else's filter). In it's current form my filter sucks because it blocks the response until the whole page has been produced by the faces servlet. I'm working on a filter that will allow me to simulate latency throughput and reliability so I can test this stuff without messing with my live installation. The filter code follows. Workaround is to insert a hidden field in your page at the point where you want the faces servlet to accept a submit request and set the hidden field's text property to "enableSubmit". the hidden field's id must be "hiddenField1" and the form "form1" (both are defaults). If someone feels like telling me how to make it non blocking (I've got to override the write method of something to do this) please feel free to let know how...

Regards

Y

import java.io.CharArrayWriter;

import java.io.PrintWriter;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpServletResponseWrapper;

/* This class 'borrowed' from Sun's example:

*See http://java.sun.com/products/servlet/Filters.html

*/

public class CharResponseWrapper extends

HttpServletResponseWrapper {

private CharArrayWriter output;

public String toString() {

return output.toString();

}

public CharResponseWrapper(HttpServletResponse response){

super(response);

output = new CharArrayWriter();

}

public PrintWriter getWriter(){

return new PrintWriter(output);

}

}

/*

* HiddenFieldFilter.java

*

* Created on 03 November 2006, 12:34

*/

import java.io.*;

import java.net.*;

import java.util.*;

import java.text.*;

import javax.servlet.*;

import javax.servlet.http.*;

import javax.servlet.Filter;

import javax.servlet.FilterChain;

import javax.servlet.FilterConfig;

import javax.servlet.ServletContext;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

/**

*

* @author yossarian

* @version

*/

public class HiddenFieldFilter implements Filter {

// The filter configuration object we are associated with. If

// this value is null, this filter instance is not currently

// configured.

private FilterConfig filterConfig = null;

public HiddenFieldFilter() {

}

private PrintWriter out;

private CharResponseWrapper wrapper;

private void doBeforeProcessing(ServletRequest request, ServletResponse response)

throws IOException, ServletException {

if (debug) log("NewSimpleFilter:DoBeforeProcessing");

//

// Write code here to process the request and/or response before

// the rest of the filter chain is invoked.

//

/*This code adapted from Suns example

*see http://java.sun.com/products/servlet/Filters.html

*/

out = response.getWriter();

wrapper = new CharResponseWrapper((HttpServletResponse)response);

}

String remove="<input id=\"form1_hidden\" name=\"form1_hidden\" value=\"form1_hidden\" type=\"hidden\" />";

String replace="<input type=\"hidden\" id=\"form1:hiddenField1\" name=\"form1:hiddenField1\" value=\"enableSubmit\" />";

private void doAfterProcessing(ServletRequest request, ServletResponse response)

throws IOException, ServletException {

if (debug) log("NewSimpleFilter:DoAfterProcessing");

//

// Write code here to process the request and/or response after

// the rest of the filter chain is invoked.

//

/* Removes the string inquestion from the stream and then injects it

*into the stream after the <form> element

*TODO see if having two fields is a problem

*TODO allow replacement based on some key field in the orginal page

*eg replace a hidden field "bananna" with the magic hidden field

*/

//<input id=\"form1:hiddenField1\" name=\"form1:hiddenField1\" type=\"hidden\" value=\"enableSubmit\" />";

if(wrapper.getContentType().indexOf("text/html")!=-1) {

//CharArrayWriter caw = new CharArrayWriter();

//// Remove hidden field

//if (debug){log("removing magic field at pos "+new Integer(res.indexOf(remove)).toString());}

//res=res.replace((CharSequence)remove, (CharSequence)"");

//if (debug){log("magic field now at pos "+new Integer(res.indexOf(remove)).toString());}

//Insert hidden field in place of our user one

// if (debug){log("exchanging user field at pos "+new Integer(res.indexOf(replace)).toString());}

String res=wrapper.toString().replace((CharSequence)replace, (CharSequence)remove);

// if (debug){log("magic field now at pos "+new Integer(res.indexOf(remove)).toString());}

//caw.write(res);

response.setContentLength(res.length());

out.write(res);

} else

out.write(wrapper.toString());

out.close();

}

/**

*

* @param request The servlet request we are processing

* @param result The servlet response we are creating

* @param chain The filter chain we are processing

*

* @exception IOException if an input/output error occurs

* @exception ServletException if a servlet error occurs

*/

public void doFilter(ServletRequest request, ServletResponse response,

FilterChain chain)

throws IOException, ServletException {

long begin = new Date().getTime();

if (debug) log("NewSimpleFilter:doFilter()");

doBeforeProcessing(request, response);

Throwable problem = null;

try {

chain.doFilter(request, wrapper);

} catch(Throwable t) {

//

// If an exception is thrown somewhere down the filter chain,

// we still want to execute our after processing, and then

// rethrow the problem after that.

//

problem = t;

t.printStackTrace();

}

doAfterProcessing(request, response);

if (debug){log("HiddenFieldFilter processing time "+ new Long(new Date().getTime()-begin).toString());}

//

// If there was a problem, we want to rethrow it if it is

// a known type, otherwise log it.

//

if (problem != null) {

if (problem instanceof ServletException) throw (ServletException)problem;

if (problem instanceof IOException) throw (IOException)problem;

sendProcessingError(problem, response);

}

}

/**

* Return the filter configuration object for this filter.

*/

public FilterConfig getFilterConfig() {

return (this.filterConfig);

}

/**

* Set the filter configuration object for this filter.

*

* @param filterConfig The filter configuration object

*/

public void setFilterConfig(FilterConfig filterConfig) {

this.filterConfig = filterConfig;

}

/**

* Destroy method for this filter

*

*/

public void destroy() {

}

/**

* Init method for this filter

*

*/

public void init(FilterConfig filterConfig) {

this.filterConfig = filterConfig;

if (filterConfig != null) {

if (debug) {

log("NewSimpleFilter:Initializing filter");

}

}

}

/**

* Return a String representation of this object.

*/

public String toString() {

if (filterConfig == null) return ("NewSimpleFilter()");

StringBuffer sb = new StringBuffer("NewSimpleFilter(");

sb.append(filterConfig);

sb.append(")");

return (sb.toString());

}

private void sendProcessingError(Throwable t, ServletResponse response) {

String stackTrace = getStackTrace(t);

if(stackTrace != null && !stackTrace.equals("")) {

try {

response.setContentType("text/html");

PrintStream ps = new PrintStream(response.getOutputStream());

PrintWriter pw = new PrintWriter(ps);

pw.print("<html>\n<head>\n<title>Error</title>\n</head>\n<body>\n"); //NOI18N

// PENDING! Localize this for next official release

pw.print("<h1>The resource did not process correctly</h1>\n<pre>\n");

pw.print(stackTrace);

pw.print("</pre></body>\n</html>"); //NOI18N

pw.close();

ps.close();

response.getOutputStream().close();;

}

catch(Exception ex){ }

} else {

try {

PrintStream ps = new PrintStream(response.getOutputStream());

t.printStackTrace(ps);

ps.close();

response.getOutputStream().close();;

} catch(Exception ex){ }

}

}

public static String getStackTrace(Throwable t) {

String stackTrace = null;

try {

StringWriter sw = new StringWriter();

PrintWriter pw = new PrintWriter(sw);

t.printStackTrace(pw);

pw.close();

sw.close();

stackTrace = sw.getBuffer().toString();

} catch(Exception ex) {}

return stackTrace;

}

public void log(String msg) {

filterConfig.getServletContext().log(msg);

}

private static final boolean debug = false;

}

Sorry -- it's a bit messy with stuff commented out etc...

yossarian at 2007-7-7 3:28:25 >