panda.net.io.CRLFLineReader Maven / Gradle / Ivy
package panda.net.io;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.Reader;
/**
* CRLFLineReader implements a readLine() method that requires exactly CRLF to terminate an input
* line. This is required for IMAP, which allows bare CR and LF.
*/
public final class CRLFLineReader extends BufferedReader {
private static final char LF = '\n';
private static final char CR = '\r';
/**
* Creates a CRLFLineReader that wraps an existing Reader input source.
*
* @param reader The Reader input source.
*/
public CRLFLineReader(Reader reader) {
super(reader);
}
/**
* Read a line of text. A line is considered to be terminated by carriage return followed
* immediately by a linefeed. This contrasts with BufferedReader which also allows other
* combinations.
*/
@Override
public String readLine() throws IOException {
StringBuilder sb = new StringBuilder();
int intch;
boolean prevWasCR = false;
synchronized (lock) { // make thread-safe (hopefully!)
while ((intch = read()) != -1) {
if (prevWasCR && intch == LF) {
return sb.substring(0, sb.length() - 1);
}
if (intch == CR) {
prevWasCR = true;
}
else {
prevWasCR = false;
}
sb.append((char)intch);
}
}
String string = sb.toString();
if (string.length() == 0) { // immediate EOF
return null;
}
return string;
}
}