CODEWITHSUNDEEP
javareadlinebufferedreaderterminator
Adrian Herscu
Adrian Herscu

Reputation: 817

reading lines from java socket with inconsistent line terminators

I am using BufferedReader#readLine() to get text lines from a TCP/IP socket.

During the same session, my server sometimes sends lines terminated with \r\n and sometimes it send lines terminated just with \n.

This behavior is not under my control :(

The Javadoc for readLine() says:

"A line is considered to be terminated by any one of a line feed ('\n'), a carriage return ('\r'), or a carriage return followed immediately by a linefeed."

Unfortunately, that does not seem to work (at least on Windows). It only "knows" to read lines ending with \r\n.

Any suggestion?

Thanks in advance, Adrian.

Upvotes: 0

Views: 3883

Answers (2)

Adrian Herscu
Adrian Herscu

Reputation: 817

Wrote a simple socket client and tested against a netcat server. The issue is that the netcat server always sends in UTF-8 and the client cannot expect UTF-16 for example.

Here is the client code:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.Socket;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.UnknownHostException;

public class LineReader {

    /**
     * @param args
     */
    public static void main(String[] args) {
        if (args.length < 2) {
            System.out.println("usage: java LineReader charset url");
            System.exit(1);
        }

        try {
            final String charset = args[0];
            final URI url = new URI(args[1]);
            final String host = url.getHost();
            final int port = url.getPort();
            final Socket socket = new Socket(host, port);
            final BufferedReader reader = new BufferedReader(
                    new InputStreamReader(socket.getInputStream(), charset));
            while (true) {
                final String line = reader.readLine();
                System.out.println(line);
            }
        } catch (URISyntaxException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (UnknownHostException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

}

Bottom line: there is no issue with the readLine method.

Upvotes: 1

Wilmer
Wilmer

Reputation: 1045

Try using the line.separator property of the underlaying OS: You could do it as follows:

static final String lineSeparator = System.getProperty ( "line.separator" );

Upvotes: 0

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