Redirecting a request using servlets and the "setHeader" method not working
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开发者_开发百科 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:)
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
Alternatively, you could try the following,
resp.setStatus(301);
resp.setHeader("Location", "index.jsp");
resp.setHeader("Connection", "close");
Another way of doing this if you want to redirect to any url source after the specified point of time
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
public class MyServlet extends HttpServlet
{
public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException
{
response.setContentType("text/html");
PrintWriter pw=response.getWriter();
pw.println("<b><centre>Redirecting to Google<br>");
response.setHeader("refresh,"5;https://www.google.com/"); // redirects to url after 5 seconds
pw.close();
}
}
加载中,请稍侯......
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