Re: UnknownHostException

manoj baba wrote:
I wanna access simple Http [sic] site...

I think ter is an error in the socket obj creation... pls help
urgent...

Unfortunately, Usenet is a terrible place for urgent needs - things proceed at a more measured pace. It's primary purpose is to serve discussion needs.

You would likely get quicker and better-quality responses if you were to spell words out in full and use normal punctuation.

import java.io.*;
import java.net.*;
public class http

Class names should start with an upper-case letter, by convention.

{
public static void main(String[] args)
{
try
{
OutputStream to_file = new FileOutputStream("f:
temp.txt");

Since you're reading text, i.e., characters, you probably should write the copy using characters, i.e., with a Writer instead of an OutputStream.

URL url = new URL("http://www.wickedlysmart.com/HeadFirst/

Is this line break in your original code or an artifact of posting to Usenet?

HeadFirstJava/HeadFirstJavaIndex.html");

Y'know, your code would be a /whole/ lot easier to read and analyze if you would use a standard indentation style (with spaces, not TAB characters). For Usenet a 2-space indent is sufficient, though some prefer 3- or 4-space indentation.

String protocol = url.getProtocol();
String host = url.getHost();
int port = url.getPort();
if(port == -1) port = 80;
String filename =url.getFile();
System.out.println(filename+"\n\n");
Socket socket = new Socket(host, port);
InputStream from_server = socket.getInputStream();
PrintWriter to_server = new PrintWriter(socket.getOutputStream());
to_server.print("Get" + filename +"\n\n");

You might need a blank between "Get" and the file name. Will this even work as you intend?

to_server.flush();
byte[] buffer = new byte[4096];
int byte_read;
while((byte_read = from_server.read(buffer)) != -1)
{
to_file.write(buffer,0,byte_read);
System.out.print((char)byte_read);

This debug output will fubar on multi-byte encodings. Logger libraries are superior to System.out for this purpose.

}
socket.close();
to_file.close();

}
catch(Exception e)
{
e.printStackTrace();
}

}
}

Output:

C:\java\bin>java Http

The case of this class invocation doesn't match the case of the class invocation. That's an error.


/HeadFirst/HeadFirstJava/HeadFirstJavaIndex.html

java.net.UnknownHostException: www.wickedlysmart.com
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:177)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:364)
at java.net.Socket.connect(Socket.java:507)
at java.net.Socket.connect(Socket.java:457)
at java.net.Socket.<init>(Socket.java:365)
at java.net.Socket.<init>(Socket.java:178)
at Http.main(Http.java:20)

Which line is line 20?


C:\java\bin>

the output file f:\temp.txt is created but empty...:(
pls help out from this error...

Let's analyze the error, shall we? Presumably the error occurred on the "new Socket()" line. This constructor is documented to throw
UnknownHostException - if the IP address of the host could not be determined.

(You've read this, presumably.)

So, your system is unable to resolve the address in question. Can you reach it with your browser? Perhaps the DNS isn't working as you expect.

--
Lew
.

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