A line reading wrapper that works with byte streams. : InputStream « File Input Output « Java

1. Java
2. File Input Output
3. InputStream

A line reading wrapper that works with byte streams.

      
/*
 * Copyright 2008-2009 SHOP.COM
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
//package com.shop.util;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;

/**
 * A line reading wrapper that works with byte streams. Has the same sematics as
 * {@link BufferedReader}<br>
 * 
 * @author Jordan Zimmerman
 */
public class LineReader extends InputStream {
  public LineReader(InputStream in) {
    fIn = in;
    fBuffer = new StringBuilder();
    fLastWasCR = false;
    fPushbackChar = 0;
  }

  @Override
  public synchronized int read() throws IOException {
    if (fPushbackChar == 0) {
      return streamRead();
    } else {
      return pushbackRead();
    }
  }

  /**
   * copied from {@link BufferedReader#readLine()}
   * 
   * Reads a line of text. 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.
   * 
   * @return A String containing the contents of the line, not including any
   *         line-termination characters, or null if the end of the stream has
   *         been reached
   * 
   * @exception IOException
   *                If an I/O error occurs
   */
  public synchronized String readLine() throws IOException {
    fBuffer.setLength(0);

    boolean eof = false;
    for (;;) {
      int b = read();
      if (b == -1) {
        eof = true;
        break;
      }

      if (b == '\r') {
        fLastWasCR = true;
        break;
      }

      if (b == '\n') {
        break;
      }
      fBuffer.append((char) (b & 0xFF));
    }
    return ((fBuffer.length() == 0) && eof) ? null : fBuffer.toString();
  }

  @Override
  public synchronized void close() throws IOException {
    super.close();
    fBuffer = null;
    fIn.close();
  }

  /**
   * Push the given char so that the next() read will return this char
   * 
   * @param c
   *            char to push back
   */
  public synchronized void pushback(int c) {
    fPushbackChar = c;
  }

  private int pushbackRead() {
    int b = fPushbackChar;
    fPushbackChar = 0;
    return b;
  }

  private int streamRead() throws IOException {
    int b = fIn.read();
    if (fLastWasCR) {
      fLastWasCR = false;

      char c = (char) (b & 0xff);
      if (c == '\n') {
        return read();
      }
    }

    return b;
  }

  private InputStream fIn;
  private StringBuilder fBuffer;
  private boolean fLastWasCR;
  private int fPushbackChar;
}

   
    
    
    
    
    
  

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