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JSP Sessions and Debugging
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(Continued from previous part...)
Passing Values between Pages
There are many ways to pass values from one pages to the next pages:
- Putting values into the session object.
- Putting values into the application object
- Putting values at the end of the redirect URL.
In the following example, I have two JSP pages working together as a registration
process. Here is the fist JSP page, RegForm.jsp:
<?xml version="1.0"?>
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="1.2">
<!-- RegForm.jsp
Copyright (c) 2002 by Dr. Herong Yang
-->
<jsp:directive.page contentType="text/html"/>
<jsp:declaration><![CDATA[
private String getItem(String queryString, String key) {
String value = null;
if (queryString!=null) {
int i = queryString.indexOf(key);
if (i>-1) {
i = i + key.length();
int j = queryString.indexOf("&",i);
if (j>-1) {
value = queryString.substring(i,j);
} else {
value = queryString.substring(i);
}
if (value.startsWith("=")) {
value = value.replaceFirst("=","");
}
}
}
return value;
}
]]></jsp:declaration>
<jsp:scriptlet><![CDATA[
String lastUser = (String) application.getAttribute("name");
if (lastUser==null) {
lastUser = "Nobody";
application.setAttribute("name",lastUser);
}
String queryString = request.getQueryString();
String submit = getItem(queryString,"submit");
if (submit!=null && submit.equals("Submit")) {
// Collecting the input data
session.setAttribute("name",getItem(queryString,"name"));
session.setAttribute("pass",getItem(queryString,"pass"));
application.setAttribute("name",getItem(queryString,"name"));
response.sendRedirect("RegDone.jsp?color="
+getItem(queryString,"color"));
} else {
// Presenting the registration form
out.print("<html><body>");
out.print("<b>Registration Form</b>:<br/>");
out.print("<form action=RegForm.jsp method=get>");
out.print("Login Name:");
out.print("<input type=text size=16 name=name><br/>");
out.print("Password:");
out.print("<input type=text size=16 name=pass><br/>");
out.print("Favor Color:");
out.print("<input type=text size=16 name=color><br/>");
out.print("<input type=submit name=submit value=Submit></br>");
out.print("</form>");
out.print("Your session ID is "+session.getId()+"<br/>");
out.print("Last user on the server: "+lastUser+"<br/>");
out.print("</body></html>");
}
]]></jsp:scriptlet>
</jsp:root>
Here is the second JSP page, RegDone.jsp:
<?xml version="1.0"?>
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="1.2">
<!-- RegDone.jsp
Copyright (c) 2002 by Dr. Herong Yang
-->
<jsp:directive.page contentType="text/html"/>
<jsp:declaration><![CDATA[
private String getItem(String queryString, String key) {
String value = null;
if (queryString!=null) {
int i = queryString.indexOf(key);
if (i>-1) {
i = i + key.length();
int j = queryString.indexOf("&",i);
if (j>-1) {
value = queryString.substring(i,j);
} else {
value = queryString.substring(i);
}
if (value.startsWith("=")) {
value = value.replaceFirst("=","");
}
}
}
return value;
}
]]></jsp:declaration>
<jsp:scriptlet><![CDATA[
out.print("<html><body>");
String lastUser = (String) application.getAttribute("name");
String queryString = request.getQueryString();
out.print("<b>Thank you for registering with us</b>:<br/>");
out.print("Login Name: "+(String)session.getAttribute("name")
+"<br/>");
out.print("Password: "+(String)session.getAttribute("pass")
+"<br/>");
out.print("Favor Color: "+getItem(queryString,"color")+"<br/>");
out.print("Your session ID is "+session.getId()+"<br/>");
out.print("Last user on the server: "+lastUser+"<br/>");
out.print("</body></html>");
]]></jsp:scriptlet>
</jsp:root>
(Continued on next part...)
Part:
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2
3
4
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