So I decided to write an example of how to do it. The example is designed to go from a JSF page to a servlet which will process the headers and display the information. The alternate example passes the request to a servlet which then passes it back to another JSF page for display. The example also demonstrates using a <f:param /> to pass additional information. The project was done using NetBeans and Maven 2.
Note: The project files can be downloaded here: jsf-servlet-forwarding.zip
As you can see from the images, the forms are very simple and used for demonstration only.
 |
| JSF Request Form |
INDEX.XHTML
<h:form id="form1">
<h:panelGrid id="panelGrid1" columns="1">
<h:outputLabel id="outputLabel1" for="inputText1" value="Please enter your name:"/>
<h:inputText id="inputText1" value="#{indexBean.name}" required="true"/>
<h:message id="message1" for="inputText1"/>
<h:panelGroup id="panelGroup1">
<h:commandButton id="commandButton1" value="Forward" type="submit" action="#{indexBean.forward}"/>
<h:commandButton id="commandButton2" value="Process" type="submit" action="#{indexBean.forward}">
<f:param id="param1" name="target" value="/results.xhtml"/>
</h:commandButton>
</h:panelGroup>
</h:panelGrid>
</h:form>
 |
| JSF -Servlet -JSF Response |
RESULTS.XHTML
This file has some interesting syntax which a number of people may not be used to seeing, for example #{param['form1:inputText1']} which is using Expression Language (EL) to read the param[] and find the specific form element which is in single quotes.
<h:body>
<p>
<h:outputText id="outputText1" value="TA DA!" style="font-weight: bold; font-size: larger; text-align: center;"/>
</p>
<p>
<h:outputText id="outputText2" value="Hello #{param['form1:inputText1']}!"/>
</p>
<p>
<h:outputText id="outputText3" value="'target' ==> #{param.target}"/>
</p>
<p>
<h:outputText id="outputText4" value="'form1:inputText1' (name) ==> #{param['form1:inputText1']}"/>
</p>
<h:form id="form1">
<h:commandButton id="commandButton1" type="submit" value="Back" action="index.xhtml"/>
</h:form>
</h:body>
 |
| Servlet Response |
PROCESSSERVLET.JAVA
/*
* Copyright 2011 Blue Lotus Software, LLC.
* Copyright 2011 John Yeary <jyeary@bluelotussoftware.com>.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* under the License.
*/
/*
* $Id: ProcessServlet.java 324 2011-01-05 03:02:41Z jyeary $
*/
package com.bluelotussoftware.example.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* An example servlet which reads the {@link javax.servlet.http.HttpServletRequest} and
* displays the values on an HTML page, or if the parameter 'target' is set, it will
* forward the {@link javax.servlet.http.HttpServletRequest} and
* {@link javax.servlet.http.HttpServletResponse}.
*
* @author John Yeary <jyeary@bluelotussoftware.com>
* @version 1.0
*/
public class ProcessServlet extends HttpServlet {
private static final long serialVersionUID = -380096497389125142L;
/**
* Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
if (request.getParameter("target") != null) {
System.out.println("TARGET: " + request.getParameter("target"));
RequestDispatcher dispatcher = request.getRequestDispatcher(request.getParameter("target"));
dispatcher.forward(request, response);
} else {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try {
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet ProcessServlet</title>");
out.println("</head>");
out.println("<body>");
out.println("<h1>Servlet ProcessServlet at " + request.getContextPath() + "</h1>");
out.println("<h2>Headers</h2>");
Enumeration<String> headers = request.getHeaderNames();
while (headers.hasMoreElements()) {
String s = headers.nextElement();
out.println("<p>" + s + " : " + request.getHeader(s) + "</p>");
}
out.println("<h2>Attributes</h2>");
Enumeration<String> attributes = request.getAttributeNames();
while (attributes.hasMoreElements()) {
String s = attributes.nextElement();
out.println("<p>" + s + " : " + request.getAttribute(s) + "</p>");
}
out.println("<h2>Parameters</h2>");
Enumeration<String> parameters = request.getParameterNames();
while (parameters.hasMoreElements()) {
String s = parameters.nextElement();
out.println("<p>" + s + " : " + request.getParameter(s) + "</p>");
}
out.println("</body>");
out.println("</html>");
} finally {
out.close();
}
}
}
// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
/**
* Handles the HTTP <code>GET</code> method.
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
/**
* Handles the HTTP <code>POST</code> method.
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
/**
* Returns a short description of the servlet.
* @return a String containing servlet description
*/
@Override
public String getServletInfo() {
return "Short description";
}// </editor-fold>
}
INDEXBEAN.JAVA
/*
* Copyright 2011 Blue Lotus Software, LLC.
* Copyright 2011 John Yeary <jyeary@bluelotussoftware.com>.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* under the License.
*/
/*
* $Id: IndexBean.java 324 2011-01-05 03:02:41Z jyeary $
*/
package com.bluelotussoftware.example.jsf.bean;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.RequestScoped;
import javax.faces.context.ExternalContext;
import javax.faces.context.FacesContext;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* {@link javax.faces.bean.ManagedBean} for the {@literal index.xhtml} which is
* used for demonstration of forwarding {@link javax.servlet.http.HttpServletRequest}
* and {@link javax.servlet.http.HttpServletResponse} to an external servlet.
*
* @author John Yeary <jyeary@bluelotussoftware.com>
* @version 1.0
*/
@ManagedBean
@RequestScoped
public class IndexBean {
/**
* Field for name.
*/
private String name;
/**
* Default Constructor
*/
public IndexBean() {
}
/**
* Getter for name field
* @return name provided.
*/
public String getName() {
return name;
}
/**
* Setter for name field.
* @param name value provided.
*/
public void setName(String name) {
this.name = name;
}
/**
* Forwards the {@link javax.servlet.http.HttpServletRequest} and
* {@link javax.servlet.http.HttpServletResponse} to a servlet URL
* pattern called {@literal /process}, and sets the {@link javax.faces.context.FacesContext#responseComplete()}.
*/
public void forward() {
try {
FacesContext ctx = FacesContext.getCurrentInstance();
ExternalContext ectx = ctx.getExternalContext();
HttpServletRequest request = (HttpServletRequest) ectx.getRequest();
HttpServletResponse response = (HttpServletResponse) ectx.getResponse();
RequestDispatcher dispatcher = request.getRequestDispatcher("/process");
dispatcher.forward(request, response);
ctx.responseComplete();
} catch (ServletException ex) {
Logger.getLogger(IndexBean.class.getName()).log(Level.SEVERE, null, ex);
} catch (IOException ex) {
Logger.getLogger(IndexBean.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
Thank you for posting this. It demonstrates the concept perfectly and saved me heaps of trial and error.
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