Re: infinite loop with http requests
On 20.11.2006 18:37, yawnmoth wrote:
I'm trying to write something that'll let me output the contents of a
given webpage while skipping over the headers. Since I'm trying to
learn raw HTTP, I'm using Sockets and not URL.
Anyway, the header of an HTTP response ends when you have "\r\n\r\n".
BufferedReader's readLine treats that as two lines since it considers
"\r\n" to be a line terminating character. Since it also strips off
the line terminating characters, readLine should return the second line
as "".
Per that, I've written a program that will loop, continuously, until ""
is encountered. Unfortunately, "" never appears to be encountered and
thus I have an infinite loop.
Here's my code:
import java.net.*;
import java.io.*;
public class HttpRequestor
{
public static void main(String[] args) {
try {
Socket sock = new Socket("www.google.com", 80);
String httpRequest = "GET / HTTP/1.0\r\nHost:
www.google.com\r\n\r\n";
sock.getOutputStream().write(httpRequest.getBytes());
BufferedReader text = new BufferedReader(new
InputStreamReader(sock.getInputStream()));
String line, output = "";
while (text.readLine() != "");
while ((line = text.readLine()) != null) {
System.out.println("\r\n'"+URLEncoder.encode(line)+"'\r\n");
}
}
catch (Exception e) {
e.printStackTrace();
}
}
}
To confirm that I was indeed getting "" back from readLine, I wrote the
following:
import java.net.*;
import java.io.*;
public class HttpRequestor
{
public static void main(String[] args) {
try {
Socket sock = new Socket("www.google.com", 80);
String httpRequest = "GET / HTTP/1.0\r\nHost:
www.google.com\r\n\r\n";
sock.getOutputStream().write(httpRequest.getBytes());
BufferedReader text = new BufferedReader(new
InputStreamReader(sock.getInputStream()));
String line, output = "";
while ((line = text.readLine()) != null) {
System.out.println("\r\n'"+URLEncoder.encode(line)+"'\r\n");
}
}
catch (Exception e) {
e.printStackTrace();
}
}
}
This shows that "" is indeed being returned by readLine. So why
doesn't the while loop in the first program terminate when "" is
received?
Because you compare strings with == (identity) instead with equals()
(equivalence).
robert
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