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I am new to servlet development, and I was reading an ebook, and found that I can redirect to a different web page using
setHeader("Location", "http://www.google.com")
But this is not working, as I have written this code as:
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class ModHelloWorld extends HttpServlet{
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException{
// response.addHeader("Location", "http://www.google.com");
response.setHeader("Location", "http://www.google.com");
response.setContentType("text/html");
PrintWriter pw = response.getWriter();
pw.println("<html><head><title>Modified Hello World</title></head><body>");
pw.println("<h1>");
//getInitParameter function reads the contents ot init-param elements.
pw.println(getInitParameter("message"));
pw.println("</h1>");
pw.println("</body></html>");
pw.close();
}
}
i have checked the headers using my program to get the headers of the webpage which is as under:
import java.net.*;
import java.io.*;
class getHeaders{
public static void main(String args[]){
URL url = null;
URLConnection urc = null;
try {
url = new URL(args[0]);
urc = url.openConnection();
for(int i=0 ; ; i++) {
String name = urc.getHeaderFieldKey(i);
String value = urc.getHeaderField(i);
if(name == null && value == null)//both null so end of header
break;
else if(name == null){//first line of header{
System.out.println("Server HTTP version, Response code: ");
System.out.println(value);
System.out.println("ENd of first header field");
} else {
System.out.println("name of header is: " + name + " and its value is : " + value);
}
}
} catch(MalformedURLException e){
System.out.println("Malformed URL " + e.getMessage());
} catch(IOException e){
e.printStackTrace();
}
}
}
And i am getting the output as:
Server HTTP version, Response code:
HTTP/1.1 200 OK
ENd of first header field
name of header is: Server and its value is : Apache-Coyote/1.1
name of header is: Location and its value is : http://www.google.com
name of header is: Content-Type and its value is : text/html
name of header is: Content-Length and its value is : 101
name of header is: Date and its value is : Sat, 05 Mar 2011 15:27:29 GMT
But I was not redirected to google's page from my browser.
Thanks in advance:)
479
setHeader. Sets a response header with the given name and value. If the header had already been set, the new value overwrites the previous one. The containsHeader method can be used to test for the presence of a header before setting its value.
Oh no no! That's not how you redirect. It's far more simpler:
public class ModHelloWorld extends HttpServlet{
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException{
response.sendRedirect("http://www.google.com");
}
}
Also, it's a bad practice to write HTML code within a servlet. You should consider putting all that markup into a JSP and invoking the JSP using:
response.sendRedirect("/path/to/mynewpage.jsp");
As you can see, the response is still HTTP/1.1 200 OK. To indicate a redirect, you need to send back a 302 status code:
response.setStatus(HttpServletResponse.SC_FOUND); // SC_FOUND = 302
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