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Servlet Interview Questions and Answers, job interview questions, interview questions, Servlet interview faqs!
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Java Servlet Interview Questions
What is CGI variables?
These are a somewhat eclectic collection of information about the request. Some are derived from the HTTP request line and headers (e.g. the part of the URI that came after the question mark and typically contains the form data, or the Content-Length header), some are derived from the socket itself (e.g. the name and IP address of the requesting host), and some are derived from server installation parameters (e.g. the mapping of URLs to actual paths).
How to read CGI variables?
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
// Creates a table showing the values of all the CGI variables.
public class ShowCGIVariables extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String[][] variables = {
{ "AUTH_TYPE", request.getAuthType() },
{ "CONTENT_LENGTH", String.valueOf(request.getContentLength()) },
{ "CONTENT_TYPE", request.getContentType() },
{ "DOCUMENT_ROOT", getServletContext().getRealPath("/") },
{ "PATH_INFO", request.getPathInfo() },
{ "PATH_TRANSLATED", request.getPathTranslated() },
{ "QUERY_STRING", request.getQueryString() },
{ "REMOTE_ADDR", request.getRemoteAddr() },
{ "REMOTE_HOST", request.getRemoteHost() },
{ "REMOTE_USER", request.getRemoteUser() },
{ "REQUEST_METHOD", request.getMethod() },
{ "SCRIPT_NAME", request.getServletPath() },
{ "SERVER_NAME", request.getServerName() },
{ "SERVER_PORT", String.valueOf(request.getServerPort()) },
{ "SERVER_PROTOCOL", request.getProtocol() },
{ "SERVER_SOFTWARE", getServletContext().getServerInfo() }
};
String title = "Servlet Example: Showing CGI Variables";
out.println(ServletUtilities.headWithTitle(title) + "<BODY BGCOLOR=\"#FDF5E6\">\n" +
"<H1 ALIGN=CENTER>" + title + "</H1>\n" +
"<TABLE BORDER=1 ALIGN=CENTER>\n" +
"<TR BGCOLOR=\"#FFAD00\">\n" +
"<TH>CGI Variable Name<TH>Value");
for(int i=0; i<variables.length; i++) {
String varName = variables[i][0];
String varValue = variables[i][1];
if (varValue == null)
varValue = "<I>Not specified</I>";
out.println("<TR><TD>" + varName + "<TD>" + varValue);
}
out.println("</TABLE></BODY></HTML>");
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
