telnetinputstream.java

具有不同语法高亮的编辑器实例

package org.fife.net;

import java.io.FilterInputStream;
import java.io.InputStream;
import java.io.IOException;


/**
 * An input stream that handles carriage returns and CR/LF pairs correctly,
 * as specified by RFC 854.
 *
 * @author Robert Futrell
 * @version 0.5
 */
public class TelnetInputStream extends FilterInputStream {

	/**
	 * Whether the stream is being read as binary.
	 */
	private boolean binary;


/*****************************************************************************/


	/**
	 * Constructor.
	 *
	 * @param in The input stream to read from.
	 * @param binary Whether or not data from <code>in</code> should be
	 *        read as binary, or as ASCII.
	 */
	public TelnetInputStream(InputStream in, boolean binary) {
		super(in);
		this.binary = binary;
	}


/*****************************************************************************/


	/**
	 * Returns whether this stream is being read as binary.
	 *
	 * @return Whether this is a binary input stream.
	 */
	public boolean isBinary() {
		return binary;
	}


/*****************************************************************************/


	/**
	 * Reads a single character from the input stream.
	 *
	 * @return The character read, or <code>-1</code> if the end of stream
	 *         has been reached.
	 * @throws IOException If an I/O error occurs.
	 */
	public int read() throws IOException {
		int ch = super.read();
		if (binary)
			return ch;
		switch (ch) {
			case '\r':
				switch (ch = super.read()) {
					case '\0': // Just a carriage return.
						return '\r';
					case '\n': // A newline.
						return '\n';
					case -1: // End of stream; this is an error.
						throw new IOException("Unexpected end-of-input");
					default: // Anything else is an error.
						throw new IOException("Invalid char after CR: " +
											((char)ch));
				}
			default:
				return ch;
		}
	}


/*****************************************************************************/


	/**
	 * Reads a given number of bytes from the input stream and stores them
	 * in the specified array.
	 *
	 * @param b The array in which to store the input.
	 * @param offset The offset into <code>b</code> at which to begin
	 *        storing.
	 * @param length The number of bytes to store.
	 * @return The number of bytes actually read.
	 * @throws IOException If an I/O error occurs.
	 */
	public int read(byte[] b, int offset, int length) throws IOException {
		if (binary)
			return super.read(b, offset, length);
		for (int i=0; i<length; i++) {
			int ch = read();
			switch (ch) {
				case -1: // End of input reached.
					return i==0 ? -1 : i;
				default:
					b[offset++] = (byte)ch;
			}
		}
		return length;
	}


/*****************************************************************************/


	/**
	 * Attempts to read a line of text from the input stream.  Since a
	 * telnet input stream always ends lines in CR/LF pairs, this method
	 * returns all characters in the stream until a CR/LF pair or the
	 * end-of-stream is reached.  If no more bytes are available in the
	 * stream, <code>null</code> is returned.
	 *
	 * @return A string representing the next line in the input stream.
	 * @throws IOException If an I/O error occurs.
	 */
	public String readLine() throws IOException {
		int ch = read();
		if (ch==-1)
			return null;
		StringBuffer buf = new StringBuffer(80);
		buf.append((char)ch);
		while (true) {
			ch = read();
			switch (ch) {
				case '\r':
					ch = read();
					switch (ch) {
						case '\n':
							return buf.toString();
						case '\0':
							buf.append('\r');
							break;
						case -1:
							throw new IOException("Unexpected end of " +
											"input");
						default:
							throw new IOException("Invalid char " +
										"after CR: " + ((char)ch));
					}
				case -1:
					return buf.toString();
				default:
					buf.append((char)ch);
			}
		}
	}


/*****************************************************************************/

}