📄 htmlscanner.java
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// HtmlScanner - a fast HTML scanning class
//
// Copyright (C)1996,1998,1999 by Jef Poskanzer <jef@acme.com>.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//
// Visit the ACME Labs Java page for up-to-date versions of this and other
// fine Java utilities: http://www.acme.com/java/
package Acme;
import java.util.*;
import java.net.*;
import java.io.*;
/// A fast HTML scanning class.
// <P>
// This is a FilterInputStream that lets you read an HTML file, and at
// the same time scans it for URLs. You get the full text of the file
// through the normal read() calls, and you also get special callbacks
// with the URL strings.
// <P>
// The scanning is done by a hand-built finite-state machine.
// <P>
// <A HREF="/resources/classes/Acme/HtmlScanner.java">Fetch the software.</A><BR>
// <A HREF="/resources/classes/Acme.tar.gz">Fetch the entire Acme package.</A>
public class HtmlScanner extends FilterInputStream
{
/// Used for maintaining correct context, even with <BASE>.
private URL contextUrl;
// The list of HtmlObservers to call, paired with clientDatas.
private Vector observers = new Vector();
/// Constructor. If the client is not interested in getting called back
// with URLs, observer can be null (but then there's not much point in
// using this class).
public HtmlScanner( InputStream s, URL thisUrl, Acme.HtmlObserver observer )
{
this( s, thisUrl, observer, null );
}
/// Constructor with clientData. If the client is not interested in
// getting called back with URLs, observer can be null (but then there's
// not much point in using this class).
public HtmlScanner( InputStream s, URL thisUrl, Acme.HtmlObserver observer, Object clientData )
{
super( s );
try
{
contextUrl = Acme.Utils.plainUrl( thisUrl.toString() );
}
catch ( MalformedURLException e ) {}
if ( observer != null )
addObserver( observer, clientData );
}
/// Add an extra observer to this scanner. Multiple observers get called
// in the order they were added.
public void addObserver( Acme.HtmlObserver observer )
{
addObserver( observer, null );
}
/// Add an extra observer to this scanner. Multiple observers get called
// in the order they were added.
public void addObserver( Acme.HtmlObserver observer, Object clientData )
{
observers.addElement( new Acme.Pair( observer, clientData ) );
}
/// Special version of read() that runs all data through the HTML scanner.
public int read( byte[] b, int off, int len ) throws IOException
{
int r = in.read( b, off, len );
if ( r != -1 )
{
r += interpret( b, off, r );
if ( r < 0 )
r = 0; // not right
}
return r;
}
private boolean closed = false;
/// Override close() with one that makes sure the entire file gets
// read, so that all its URLs get extracted, even if the caller isn't
// interested in the data.
public void close() throws IOException
{
if ( ! closed ) // protect against double closes
{
byte[] b = new byte[4096];
int len;
while ( ( len = read( b, 0, b.length ) ) != -1 )
{}
in.close();
closed = true;
}
}
/// Add a finalize method to try and make sure that our
// jiggered close() gets called.
// @exception java.lang.Throwable if there's a problem
protected void finalize() throws java.lang.Throwable
{
try
{
close();
}
catch ( IOException e )
{}
super.finalize();
}
/// Override to make sure this goes through the above
// read( byte[], int, int) method.
public int read() throws IOException
{
byte[] b = new byte[1];
int r = read( b, 0, 1 );
if ( r == -1 )
return -1;
else
return b[0];
}
/// Override to make sure this goes through the above
// read( byte[], int, int) method.
public int read( byte[] b ) throws IOException
{
return read( b, 0, b.length );
}
/// Override to make sure this goes through the above
// read( byte[], int, int) method.
public long skip( long n ) throws IOException
{
byte[] b = new byte[(int) n]; // mildly bogus
return read( b, 0, (int) n );
}
/// Disallow mark()/reset().
public boolean markSupported()
{
return false;
}
// And here's the fun part - a finite-state-machine HTML scanner.
//
// Knows about: <!-- --> <A HREF=""> <IMG SRC=""> <FRAME SRC="">
// <BASE HREF=""> <AREA HREF=""> <LINK HREF=""> <BODY BACKGROUND="">
// <INPUT TYPE="image" SRC="">
//
// This is a big mess-o-code and not very maintainable or extendable, but
// it's fast and doesn't compile to as much object code as you'd think.
private final static int ST_GROUND = 0;
private final static int ST_LT = 1;
private final static int ST_LTJUNK = 2;
private final static int ST_LT_BANG = 3;
private final static int ST_LT_BANG_DASH = 4;
private final static int ST_COMMENT = 5;
private final static int ST_COMMENT_DASH = 6;
private final static int ST_COMMENT_DASH_DASH = 7;
private final static int ST_LT_A = 8;
private final static int ST_A = 9;
private final static int ST_A_QUOTE = 10;
private final static int ST_A_H = 11;
private final static int ST_A_HR = 12;
private final static int ST_A_HRE = 13;
private final static int ST_A_HREF = 14;
private final static int ST_A_HREF_EQUAL = 15;
private final static int ST_AHREF_Q = 16;
private final static int ST_AHREF_NQ = 17;
private final static int ST_LT_I = 18;
private final static int ST_LT_IM = 19;
private final static int ST_LT_IMG = 20;
private final static int ST_IMG = 21;
private final static int ST_IMG_QUOTE = 22;
private final static int ST_IMG_S = 23;
private final static int ST_IMG_SR = 24;
private final static int ST_IMG_SRC = 25;
private final static int ST_IMG_SRC_EQUAL = 26;
private final static int ST_IMGSRC_Q = 27;
private final static int ST_IMGSRC_NQ = 28;
private final static int ST_LT_F = 29;
private final static int ST_LT_FR = 30;
private final static int ST_LT_FRA = 31;
private final static int ST_LT_FRAM = 32;
private final static int ST_LT_FRAME = 33;
private final static int ST_FRAME = 34;
private final static int ST_FRAME_QUOTE = 35;
private final static int ST_FRAME_S = 36;
private final static int ST_FRAME_SR = 37;
private final static int ST_FRAME_SRC = 38;
private final static int ST_FRAME_SRC_EQUAL = 39;
private final static int ST_FRAMESRC_Q = 40;
private final static int ST_FRAMESRC_NQ = 41;
private final static int ST_LT_B = 42;
private final static int ST_LT_BA = 43;
private final static int ST_LT_BAS = 44;
private final static int ST_LT_BASE = 45;
private final static int ST_BASE = 46;
private final static int ST_BASE_QUOTE = 47;
private final static int ST_BASE_H = 48;
private final static int ST_BASE_HR = 49;
private final static int ST_BASE_HRE = 50;
private final static int ST_BASE_HREF = 51;
private final static int ST_BASE_HREF_EQUAL = 52;
private final static int ST_BASEHREF_Q = 53;
private final static int ST_BASEHREF_NQ = 54;
private final static int ST_LT_AR = 55;
private final static int ST_LT_ARE = 56;
private final static int ST_LT_AREA = 57;
private final static int ST_AREA = 58;
private final static int ST_AREA_QUOTE = 59;
private final static int ST_AREA_H = 60;
private final static int ST_AREA_HR = 61;
private final static int ST_AREA_HRE = 62;
private final static int ST_AREA_HREF = 63;
private final static int ST_AREA_HREF_EQUAL = 64;
private final static int ST_AREAHREF_Q = 65;
private final static int ST_AREAHREF_NQ = 66;
private final static int ST_LT_L = 67;
private final static int ST_LT_LI = 68;
private final static int ST_LT_LIN = 69;
private final static int ST_LT_LINK = 70;
private final static int ST_LINK = 71;
private final static int ST_LINK_QUOTE = 72;
private final static int ST_LINK_H = 73;
private final static int ST_LINK_HR = 74;
private final static int ST_LINK_HRE = 75;
private final static int ST_LINK_HREF = 76;
private final static int ST_LINK_HREF_EQUAL = 77;
private final static int ST_LINKHREF_Q = 78;
private final static int ST_LINKHREF_NQ = 79;
private final static int ST_LT_BO = 80;
private final static int ST_LT_BOD = 81;
private final static int ST_LT_BODY = 82;
private final static int ST_BODY = 83;
private final static int ST_BODY_QUOTE = 84;
private final static int ST_BODY_B = 85;
private final static int ST_BODY_BA = 86;
private final static int ST_BODY_BAC = 87;
private final static int ST_BODY_BACK = 88;
private final static int ST_BODY_BACKG = 89;
private final static int ST_BODY_BACKGR = 90;
private final static int ST_BODY_BACKGRO = 91;
private final static int ST_BODY_BACKGROU = 92;
private final static int ST_BODY_BACKGROUN = 93;
private final static int ST_BODY_BACKGROUND = 94;
private final static int ST_BODY_BACKGROUND_EQUAL = 95;
private final static int ST_BODYBACKGROUND_Q = 96;
private final static int ST_BODYBACKGROUND_NQ = 97;
private final static int ST_LT_IN = 98;
private final static int ST_LT_INP = 99;
private final static int ST_LT_INPU = 100;
private final static int ST_LT_INPUT = 101;
private final static int ST_INPUT = 102;
private final static int ST_INPUT_QUOTE = 103;
private final static int ST_INPUT_S = 104;
private final static int ST_INPUT_SR = 105;
private final static int ST_INPUT_SRC = 106;
private final static int ST_INPUT_SRC_EQUAL = 107;
private final static int ST_INPUTSRC_Q = 108;
private final static int ST_INPUTSRC_NQ = 109;
private int state = ST_GROUND;
private StringBuffer urlBuf = new StringBuffer( 100 );
/// Whether the interpreter is currently accumulating a URL.
protected boolean gettingUrl = false;
// Shared with substitute().
private byte[] interpBuf;
private int interpIndex;
private int interpEnd;
private int interpDelta;
/// Run the finite-state machine on a buffer-load.
private int interpret( byte[] b, int off, int len )
{
interpBuf = b;
interpDelta = 0;
interpEnd = off + len;
for ( interpIndex = off; interpIndex < interpEnd; ++interpIndex )
{
char ch = (char) b[interpIndex];
switch ( state )
{
case ST_GROUND:
switch ( ch )
{
case '<': state = ST_LT; break;
default: break;
}
break;
case ST_LT:
switch ( ch )
{
case '!': state = ST_LT_BANG; break;
case 'A': case 'a': state = ST_LT_A; break;
case 'B': case 'b': state = ST_LT_B; break;
case 'F': case 'f': state = ST_LT_F; break;
case 'I': case 'i': state = ST_LT_I; break;
case 'L': case 'l': state = ST_LT_L; break;
case '>': state = ST_GROUND; break;
default: state = ST_LTJUNK; break;
}
break;
case ST_LTJUNK:
switch ( ch )
{
case '>': state = ST_GROUND; break;
default: break;
}
break;
case ST_LT_BANG:
switch ( ch )
{
case '-': state = ST_LT_BANG_DASH; break;
case '>': state = ST_GROUND; break;
default: state = ST_LTJUNK; break;
}
break;
case ST_LT_BANG_DASH:
switch ( ch )
{
case '-': state = ST_COMMENT; break;
case '>': state = ST_GROUND; break;
default: state = ST_LTJUNK; break;
}
break;
case ST_COMMENT:
switch ( ch )
{
case '-': state = ST_COMMENT_DASH; break;
default: break;
}
break;
case ST_COMMENT_DASH:
switch ( ch )
{
case '-': state = ST_COMMENT_DASH_DASH; break;
default: break;
}
break;
case ST_COMMENT_DASH_DASH:
switch ( ch )
{
case '>': state = ST_GROUND; break;
default: break;
}
break;
case ST_LT_A:
switch ( ch )
{
case ' ': case '\t': case '\n': case '\r':
state = ST_A; break;
case 'R': case 'r': state = ST_LT_AR; break;
case '>': state = ST_GROUND; break;
default: state = ST_LTJUNK; break;
}
break;
case ST_A:
switch ( ch )
{
case '>': state = ST_GROUND; break;
case '"': state = ST_A_QUOTE; break;
case 'H': case 'h': state = ST_A_H; break;
default: break;
}
break;
case ST_A_QUOTE:
switch ( ch )
{
case '"': state = ST_A; break;
default: break;
}
break;
case ST_A_H:
switch ( ch )
{
case 'R': case 'r': state = ST_A_HR; break;
case '"': state = ST_A_QUOTE; break;
default: state = ST_A; break;
}
break;
case ST_A_HR:
switch ( ch )
{
case 'E': case 'e': state = ST_A_HRE; break;
case '"': state = ST_A_QUOTE; break;
default: state = ST_A; break;
}
break;
case ST_A_HRE:
switch ( ch )
{
case 'F': case 'f': state = ST_A_HREF; break;
case '"': state = ST_A_QUOTE; break;
default: state = ST_A; break;
}
break;
case ST_A_HREF:
switch ( ch )
{
case ' ': case '\t': case '\n': case '\r': break;
case '=': state = ST_A_HREF_EQUAL; break;
case '"': state = ST_A_QUOTE; break;
default: state = ST_A; break;
}
break;
case ST_A_HREF_EQUAL:
// Start accumulating a URL.
gettingUrl = true;
urlBuf.setLength( 0 );
switch ( ch )
{
case ' ': case '\t': case '\n': case '\r': break;
case '"': state = ST_AHREF_Q; break;
default:
// Accumulate the URL.
urlBuf.append( ch );
state = ST_AHREF_NQ;
break;
}
break;
case ST_AHREF_Q:
switch ( ch )
{
case '"':
// Got a complete URL.
callAHREF( urlBuf.toString() );
gettingUrl = false;
state = ST_A;
break;
default:
// Accumulate the URL.
urlBuf.append( ch );
break;
}
break;
case ST_AHREF_NQ:
switch ( ch )
{
case '>':
case ' ': case '\t': case '\n': case '\r':
// Got a complete URL.
callAHREF( urlBuf.toString() );
gettingUrl = false;
state = ( ch == '>' ? ST_GROUND : ST_A );
break;
default:
// Accumulate the URL.
urlBuf.append( ch );
break;
}
break;
case ST_LT_I:
switch ( ch )
{
case 'M': case 'm': state = ST_LT_IM; break;
case 'N': case 'n': state = ST_LT_IN; break;
case '>': state = ST_GROUND; break;
default: state = ST_LTJUNK; break;
}
break;
case ST_LT_IM:
switch ( ch )
{
case 'G': case 'g': state = ST_LT_IMG; break;
case '>': state = ST_GROUND; break;
default: state = ST_LTJUNK; break;
}
break;
case ST_LT_IMG:
switch ( ch )
{
case ' ': case '\t': case '\n': case '\r':
state = ST_IMG; break;
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