Size Limit InputStream : InputStream « File Input Output « Java

Home
Java
1.2D Graphics GUI
2.3D
3.Advanced Graphics
4.Ant
5.Apache Common
6.Chart
7.Class
8.Collections Data Structure
9.Data Type
10.Database SQL JDBC
11.Design Pattern
12.Development Class
13.EJB3
14.Email
15.Event
16.File Input Output
17.Game
18.Generics
19.GWT
20.Hibernate
21.I18N
22.J2EE
23.J2ME
24.JDK 6
25.JNDI LDAP
26.JPA
27.JSP
28.JSTL
29.Language Basics
30.Network Protocol
31.PDF RTF
32.Reflection
33.Regular Expressions
34.Scripting
35.Security
36.Servlets
37.Spring
38.Swing Components
39.Swing JFC
40.SWT JFace Eclipse
41.Threads
42.Tiny Application
43.Velocity
44.Web Services SOA
45.XML
Java » File Input Output » InputStreamScreenshots 
Size Limit InputStream
    
/*
 * Input stream wrapper with a byte limit.
 * Copyright (C) 2004 Stephen Ostermiller
 * http://ostermiller.org/contact.pl?regarding=Java+Utilities
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * See COPYING.TXT for details.
 */

import java.io.*;

/**
 * An input stream wrapper that will read only a set number of bytes from the
 * underlying stream.
 *
 @author Stephen Ostermiller http://ostermiller.org/contact.pl?regarding=Java+Utilities
 @since ostermillerutils 1.04.00
 */
public class SizeLimitInputStream extends InputStream {

  /**
   * The input stream that is being protected.
   * All methods should be forwarded to it,
   * after checking the size that has been read.
   *
   @since ostermillerutils 1.04.00
   */
  protected InputStream in;

  /**
   * The number of bytes to read at most from this
   * Stream.  Read methods should
   * check to ensure that bytesRead never
   * exceeds maxBytesToRead.
   *
   @since ostermillerutils 1.04.00
   */
  protected long maxBytesToRead = 0;

  /**
   * The number of bytes that have been read
   * from this stream.  Read methods should
   * check to ensure that bytesRead never
   * exceeds maxBytesToRead.
   *
   @since ostermillerutils 1.04.00
   */
  protected long bytesRead = 0;

  /**
   * The number of bytes that have been read
   * from this stream since mark() was called.
   *
   @since ostermillerutils 1.04.00
   */
  protected long bytesReadSinceMark = 0;

  /**
   * The number of bytes the user has request
   * to have been marked for reset.
   *
   @since ostermillerutils 1.04.00
   */
  protected long markReadLimitBytes = -1;

  /**
   * Get the number of bytes actually read
   * from this stream.
   *
   @return number of bytes that have already been taken from this stream.
   *
   @since ostermillerutils 1.04.00
   */
  public long getBytesRead(){
    return bytesRead;
  }

  /**
   * Get the maximum number of bytes left to read
   * before the limit (set in the constructor) is reached.
   *
   @return The number of bytes that (at a maximum) are left to be taken from this stream.
   *
   @since ostermillerutils 1.04.00
   */
  public long getBytesLeft(){
    return maxBytesToRead - bytesRead;
  }

  /**
   * Tell whether the number of bytes specified
   * in the constructor have been read yet.
   *
   @return true iff the specified number of bytes have all been read.
   *
   @since ostermillerutils 1.04.00
   */
  public boolean allBytesRead(){
    return getBytesLeft() == 0;
  }

  /**
   * Get the number of total bytes (including bytes already read)
   * that can be read from this stream (as set in the constructor).
   @return Maximum bytes that can be read until the size limit runs out
   *
   @since ostermillerutils 1.04.00
   */
  public long getMaxBytesToRead(){
    return maxBytesToRead;
  }

  /**
   * Create a new size limit input stream from
   * another stream given a size limit.
   *
   @param in The input stream.
   @param maxBytesToRead the max number of bytes to allow to be read from the underlying stream.
   *
   @since ostermillerutils 1.04.00
   */
  public SizeLimitInputStream(InputStream in, long maxBytesToRead){
    this.in = in;
    this.maxBytesToRead = maxBytesToRead;
  }

  /**
   * {@inheritDoc}
   */
  @Override public int read() throws IOException {
    if (bytesRead >= maxBytesToRead){
      return -1;
    }
    int b = in.read();
    if(b != -1){
      bytesRead++;
      bytesReadSinceMark++;
    }
    return b;
  }

  /**
   * {@inheritDoc}
   */
  @Override public int read(byte[] bthrows IOException {
    return this.read(b, 0, b.length);
  }

  /**
   * {@inheritDoc}
   */
  @Override public int read(byte[] b, int off, int lenthrows IOException {
    if (bytesRead >= maxBytesToRead){
      return -1;
    }
    long bytesLeft = getBytesLeft();
    if (len > bytesLeft){
      len = (int)bytesLeft;
    }
    int bytesJustRead = in.read(b, off, len);
    bytesRead += bytesJustRead;
    bytesReadSinceMark += bytesJustRead;
    return bytesJustRead;
  }

  /**
   * {@inheritDoc}
   */
  @Override public long skip(long nthrows IOException {
    if (bytesRead >= maxBytesToRead){
      return -1;
    }
    long bytesLeft = getBytesLeft();
    if (n > bytesLeft){
      n = bytesLeft;
    }
    return in.skip(n);
  }

  /**
   * {@inheritDoc}
   */
  @Override public int available() throws IOException {
    int available = in.available();
    long bytesLeft = getBytesLeft();
    if (available > bytesLeft){
      available = (int)bytesLeft;
    }
    return available;
  }

  /**
   * Close this stream and underlying streams.
   * Calling this method may make data on the
   * underlying stream unavailable.
   * <p>
   * Consider wrapping this stream in a NoCloseStream
   * so that clients can
   * call close() with no effect.
   *
   @since ostermillerutils 1.04.00
   */
  @Override public void close() throws IOException {
    in.close();
  }

  /**
   * {@inheritDoc}
   */
  @Override public void mark(int readlimit){
    if (in.markSupported()){
      markReadLimitBytes = readlimit;
      bytesReadSinceMark = 0;
      in.mark(readlimit);
    }
  }

  /**
   * {@inheritDoc}
   */
  @Override public void reset() throws IOException {
    if (in.markSupported() && bytesReadSinceMark <= markReadLimitBytes){
      bytesRead -= bytesReadSinceMark;
      in.reset();
      bytesReadSinceMark = 0;
    }
  }

  /**
   * {@inheritDoc}
   */
  @Override public boolean markSupported(){
    return in.markSupported();
  }
}

   
    
    
    
  
Related examples in the same category
1.Creating an input or output stream on a ByteBuffer
2.Creating a Manifest for a JAR File
3.Convert InputStream to String
4.An limited-data-size input stream
5.An input stream which reads sequentially from multiple sources
6.Combined InputStream
7.Minimal InputStream subclass to fetch bytes form a String
8.Read and return the entire contents of the supplied InputStream. This method always closes the stream when finished reading.
9.Compare two InputStream
10.Read and return the entire contents of the supplied InputStream.
11.Deserializes an object from an input stream.
12.Reads at most certain bytes from input stream and returns them as a byte array.
13.Convert Reader to InputStream
14.A trace of the data that is being retrieved from an input stream
15.EOLConvertingInputStream: InputStream which converts \r bytes not followed by \n and \n not preceded by \r to \r\n.
16.A line reading wrapper that works with byte streams.
17.Smart Encoding InputStream
18.Wraps a stream that has been exported to import the data in readable form
19.This input stream wrapper closes the base input stream when fully read.
20.LZFInputStream and LZFOutputStream
21.Random input stream
java2s.com  | Contact Us | Privacy Policy
Copyright 2009 - 12 Demo Source and Support. All rights reserved.
All other trademarks are property of their respective owners.