JSP pageContext Object is implicitly available to the developer on Java Server Pages. A pageContext implicit object is used for storing and retrieving page-related information and sharing objects within the same translation unit and same request. Also used as a convenience class that maintains a table of all the other implicit objects.
It stores referece to the implicit objects-
The following example shows how PageContext is used to populate other implicit objects.
public void _jspService (HttpServletRequest request, HttpServletResponse response)
throws java.io.IOException, ServletException {
...
try {
...
application = pageContext.getServletContext ();
config = pageContext.getServletConfig ();
session = pageContext.getSession ();
out = pageContext.getOut ();
...
} catch (Throwable t) {
...
} finally {
...
}
}
Provides convenience methods to get and set attributes in different scopes-
This example uses attributes to save and retrieve data in each of the four scopes:
<%
// Save data
pageContext.setAttribute("attr1", "value0"); // PAGE_SCOPE is the default
pageContext.setAttribute("attr2", "value1", PageContext.PAGE_SCOPE);
pageContext.setAttribute("attr3", "value2", PageContext.REQUEST_SCOPE);
pageContext.setAttribute("attr4", "value3", PageContext.SESSION_SCOPE);
pageContext.setAttribute("attr5", "value4", PageContext.APPLICATION_SCOPE);
%>
<%-- Show the values --%>
<%= pageContext.getAttribute("attr1") %>
<%= pageContext.getAttribute("attr2", PageContext.PAGE_SCOPE) %>
<%= pageContext.getAttribute("attr3", PageContext.REQUEST_SCOPE) %>
<%= pageContext.getAttribute("attr4", PageContext.SESSION_SCOPE) %>
<%= pageContext.getAttribute("attr5", PageContext.APPLICATION_SCOPE) %>
JSP pageContext Object Example:
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>JSP pageContext Object Example</title>
</head>
<body>
<%
JspWriter pw = pageContext.getOut();
pw.print("Hello Dinesh....This is another example of JSP 'pageContext' object");
%>
</body>
</html>
As you can see above, using JSP pageContext object, JspWriter instance is created. Using this JspWriter object, String response is set that displayed on the browser when JSP served a request.
