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// HTMLParser Library $Name: v1_5 $ - A java-based parser for HTML
// http://sourceforge.org/projects/htmlparser
// Copyright (C) 2004 Derrick Oswald
//
// Revision Control Information
//
// $Source: /cvsroot/htmlparser/htmlparser/src/org/htmlparser/lexer/Page.java,v $
// $Author: derrickoswald $
// $Date: 2005/05/15 11:49:04 $
// $Revision: 1.50 $
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//

package org.htmlparser.lexer;

import java.io.InputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.net.UnknownHostException;
import java.util.zip.GZIPInputStream;
import java.util.zip.InflaterInputStream;

import org.htmlparser.http.ConnectionManager;
import org.htmlparser.util.ParserException;

/**
 * Represents the contents of an HTML page.
 * Contains the source of characters and an index of positions of line
 * separators (actually the first character position on the next line).
 */
public class Page
    implements
        Serializable
{
    /**
     * The default charset.
     * This should be {@value},
     * see RFC 2616 (http://www.ietf.org/rfc/rfc2616.txt?number=2616)
     * section 3.7.1
     * 

Another alias is "8859_1". */ public static final String DEFAULT_CHARSET = "ISO-8859-1"; /** * The default content type. * In the absence of alternate information, assume html content ({@value}). */ public static final String DEFAULT_CONTENT_TYPE = "text/html"; /** * Character value when the page is exhausted. * Has a value of {@value}. */ public static final char EOF = (char)Source.EOF; /** * The URL this page is coming from. * Cached value of getConnection().toExternalForm() or * setUrl(). */ protected String mUrl; /** * The base URL for this page. */ protected String mBaseUrl; /** * The source of characters. */ protected Source mSource; /** * Character positions of the first character in each line. */ protected PageIndex mIndex; /** * The connection this page is coming from or null. */ protected transient URLConnection mConnection; /** * Connection control (proxy, cookies, authorization). */ protected static ConnectionManager mConnectionManager = new ConnectionManager (); /** * Construct an empty page. */ public Page () { this (""); } /** * Construct a page reading from a URL connection. * @param connection A fully conditioned connection. The connect() * method will be called so it need not be connected yet. * @exception ParserException An exception object wrapping a number of * possible error conditions, some of which are outlined below. *

  • IOException If an i/o exception occurs creating the * source.
  • *
  • UnsupportedEncodingException if the character set specified in the * HTTP header is not supported.
  • */ public Page (URLConnection connection) throws ParserException { if (null == connection) throw new IllegalArgumentException ("connection cannot be null"); setConnection (connection); mBaseUrl = null; } /** * Construct a page from a stream encoded with the given charset. * @param stream The source of bytes. * @param charset The encoding used. * If null, defaults to the DEFAULT_CHARSET. * @exception UnsupportedEncodingException If the given charset * is not supported. */ public Page (InputStream stream, String charset) throws UnsupportedEncodingException { if (null == stream) throw new IllegalArgumentException ("stream cannot be null"); if (null == charset) charset = DEFAULT_CHARSET; mSource = new InputStreamSource (stream, charset); mIndex = new PageIndex (this); mConnection = null; mUrl = null; mBaseUrl = null; } /** * Construct a page from the given string. * @param text The HTML text. * @param charset Optional. The character set encoding that will * be reported by {@link #getEncoding}. If charset is null * the default character set is used. */ public Page (String text, String charset) { if (null == text) throw new IllegalArgumentException ("text cannot be null"); if (null == charset) charset = DEFAULT_CHARSET; mSource = new StringSource (text, charset); mIndex = new PageIndex (this); mConnection = null; mUrl = null; mBaseUrl = null; } /** * Construct a page from the given string. * The page will report that it is using an encoding of * {@link #DEFAULT_CHARSET}. * @param text The HTML text. */ public Page (String text) { this (text, null); } /** * Construct a page from a source. * @param source The source of characters. */ public Page (Source source) { if (null == source) throw new IllegalArgumentException ("source cannot be null"); mSource = source; mIndex = new PageIndex (this); mConnection = null; mUrl = null; mBaseUrl = null; } // // static methods // /** * Get the connection manager all Parsers use. * @return The connection manager. */ public static ConnectionManager getConnectionManager () { return (mConnectionManager); } /** * Set the connection manager to use. * @param manager The new connection manager. */ public static void setConnectionManager (ConnectionManager manager) { mConnectionManager = manager; } /** * Get a CharacterSet name corresponding to a charset parameter. * @param content A text line of the form: *
         * text/html; charset=Shift_JIS
         * 
    * which is applicable both to the HTTP header field Content-Type and * the meta tag http-equiv="Content-Type". * Note this method also handles non-compliant quoted charset directives * such as: *
         * text/html; charset="UTF-8"
         * 
    * and *
         * text/html; charset='UTF-8'
         * 
    * @return The character set name to use when reading the input stream. * For JDKs that have the Charset class this is qualified by passing * the name to findCharset() to render it into canonical form. * If the charset parameter is not found in the given string, the default * character set is returned. * @see #findCharset * @see #DEFAULT_CHARSET */ public static String getCharset (String content) { final String CHARSET_STRING = "charset"; int index; String ret; ret = DEFAULT_CHARSET; if (null != content) { index = content.indexOf (CHARSET_STRING); if (index != -1) { content = content.substring (index + CHARSET_STRING.length ()).trim (); if (content.startsWith ("=")) { content = content.substring (1).trim (); index = content.indexOf (";"); if (index != -1) content = content.substring (0, index); //remove any double quotes from around charset string if (content.startsWith ("\"") && content.endsWith ("\"") && (1 < content.length ())) content = content.substring (1, content.length () - 1); //remove any single quote from around charset string if (content.startsWith ("'") && content.endsWith ("'") && (1 < content.length ())) content = content.substring (1, content.length () - 1); ret = findCharset (content, ret); // Charset names are not case-sensitive; // that is, case is always ignored when comparing // charset names. // if (!ret.equalsIgnoreCase (content)) // { // System.out.println ( // "detected charset \"" // + content // + "\", using \"" // + ret // + "\""); // } } } } return (ret); } /** * Lookup a character set name. * Vacuous for JVM's without java.nio.charset. * This uses reflection so the code will still run under prior JDK's but * in that case the default is always returned. * @param name The name to look up. One of the aliases for a character set. * @param fallback The name to return if the lookup fails. * @return The character set name. */ public static String findCharset (String name, String fallback) { String ret; try { Class cls; Method method; Object object; cls = Class.forName ("java.nio.charset.Charset"); method = cls.getMethod ("forName", new Class[] { String.class }); object = method.invoke (null, new Object[] { name }); method = cls.getMethod ("name", new Class[] { }); object = method.invoke (object, new Object[] { }); ret = (String)object; } catch (ClassNotFoundException cnfe) { // for reflection exceptions, assume the name is correct ret = name; } catch (NoSuchMethodException nsme) { // for reflection exceptions, assume the name is correct ret = name; } catch (IllegalAccessException ia) { // for reflection exceptions, assume the name is correct ret = name; } catch (InvocationTargetException ita) { // java.nio.charset.IllegalCharsetNameException // and java.nio.charset.UnsupportedCharsetException // return the default ret = fallback; System.out.println ( "unable to determine cannonical charset name for " + name + " - using " + fallback); } return (ret); } // // Serialization support // /** * Serialize the page. * There are two modes to serializing a page based on the connected state. * If connected, the URL and the current offset is saved, while if * disconnected, the underling source is saved. * @param out The object stream to store this object in. * @exception IOException If there is a serialization problem. */ private void writeObject (ObjectOutputStream out) throws IOException { String href; Source source; PageIndex index; // two cases, reading from a URL and not if (null != getConnection ()) { out.writeBoolean (true); out.writeInt (mSource.offset ()); // need to preread this much href = getUrl (); out.writeObject (href); setUrl (getConnection ().getURL ().toExternalForm ()); source = getSource (); mSource = null; // don't serialize the source if we can avoid it index = mIndex; mIndex = null; // will get recreated; valid for the new page anyway? out.defaultWriteObject (); mSource = source; mIndex = index; } else { out.writeBoolean (false); href = getUrl (); out.writeObject (href); setUrl (null); // don't try and read a bogus URL out.defaultWriteObject (); setUrl (href); } } /** * Deserialize the page. * For details see writeObject(). * @param in The object stream to decode. * @exception IOException If there is a deserialization problem with * the stream. * @exception ClassNotFoundException If the deserialized class can't be * located with the current classpath and class loader. */ private void readObject (ObjectInputStream in) throws IOException, ClassNotFoundException { boolean fromurl; int offset; String href; URL url; Cursor cursor; fromurl = in.readBoolean (); if (fromurl) { offset = in.readInt (); href = (String)in.readObject (); in.defaultReadObject (); // open the URL if (null != getUrl ()) { url = new URL (getUrl ()); try { setConnection (url.openConnection ()); } catch (ParserException pe) { throw new IOException (pe.getMessage ()); } } cursor = new Cursor (this, 0); for (int i = 0; i < offset; i++) try { getCharacter (cursor); } catch (ParserException pe) { throw new IOException (pe.getMessage ()); } setUrl (href); } else { href = (String)in.readObject (); in.defaultReadObject (); setUrl (href); } } /** * Reset the page by resetting the source of characters. */ public void reset () { getSource ().reset (); mIndex = new PageIndex (this); // todo: is this really necessary? } /** * Close the page by destroying the source of characters. * @exception IOException If destroying the source encounters an error. */ public void close () throws IOException { if (null != getSource ()) getSource ().destroy (); } /** * Clean up this page, releasing resources. * Calls close(). * @exception Throwable if close() throws an * IOException. */ protected void finalize () throws Throwable { close (); } /** * Get the connection, if any. * @return The connection object for this page, or null if this page * is built from a stream or a string. */ public URLConnection getConnection () { return (mConnection); } /** * Set the URLConnection to be used by this page. * Starts reading from the given connection. * This also resets the current url. * @param connection The connection to use. * It will be connected by this method. * @exception ParserException If the connect() method fails, * or an I/O error occurs opening the input stream or the character set * designated in the HTTP header is unsupported. */ public void setConnection (URLConnection connection) throws ParserException { Stream stream; String type; String charset; String contentEncoding; mConnection = connection; try { getConnection ().connect (); } catch (UnknownHostException uhe) { throw new ParserException ("Connect to " + mConnection.getURL ().toExternalForm () + " failed.", uhe); } catch (IOException ioe) { throw new ParserException ("Exception connecting to " + mConnection.getURL ().toExternalForm () + " (" + ioe.getMessage () + ").", ioe); } type = getContentType (); charset = getCharset (type); try { contentEncoding = connection.getContentEncoding(); if ((null != contentEncoding) && (-1 != contentEncoding.indexOf ("gzip"))) { stream = new Stream (new GZIPInputStream ( getConnection ().getInputStream ())); } else if ((null != contentEncoding) && (-1 != contentEncoding.indexOf ("deflate"))) { stream = new Stream (new InflaterInputStream ( getConnection ().getInputStream ())); } else { stream = new Stream (getConnection ().getInputStream ()); } try { mSource = new InputStreamSource (stream, charset); } catch (UnsupportedEncodingException uee) { // StringBuilder msg; // // msg = new StringBuilder (1024); // msg.append (getConnection ().getURL ().toExternalForm ()); // msg.append (" has an encoding ("); // msg.append (charset); // msg.append (") which is not supported, using "); // msg.append (DEFAULT_CHARSET); // System.out.println (msg.toString ()); charset = DEFAULT_CHARSET; mSource = new InputStreamSource (stream, charset); } } catch (IOException ioe) { throw new ParserException ("Exception getting input stream from " + mConnection.getURL ().toExternalForm () + " (" + ioe.getMessage () + ").", ioe); } mUrl = connection.getURL ().toExternalForm (); mIndex = new PageIndex (this); } /** * Get the URL for this page. * This is only available if the page has a connection * (getConnection() returns non-null), or the document base has * been set via a call to setUrl(). * @return The url for the connection, or null if there is * no conenction or the document base has not been set. */ public String getUrl () { return (mUrl); } /** * Set the URL for this page. * This doesn't affect the contents of the page, just the interpretation * of relative links from this point forward. * @param url The new URL. */ public void setUrl (String url) { mUrl = url; } /** * Gets the baseUrl. * @return The base URL for this page, or null if not set. */ public String getBaseUrl () { return (mBaseUrl); } /** * Sets the baseUrl. * @param url The base url for this page. */ public void setBaseUrl (String url) { mBaseUrl = url; } /** * Get the source this page is reading from. * @return The current source. */ public Source getSource () { return (mSource); } /** * Try and extract the content type from the HTTP header. * @return The content type. */ public String getContentType () { URLConnection connection; String content; String ret; ret = DEFAULT_CONTENT_TYPE; connection = getConnection (); if (null != connection) { content = connection.getContentType (); if (null != content) ret = content; } return (ret); } /** * Read the character at the given cursor position. * The cursor position can be only behind or equal to the * current source position. * Returns end of lines (EOL) as \n, by converting \r and \r\n to \n, * and updates the end-of-line index accordingly * Advances the cursor position by one (or two in the \r\n case). * @param cursor The position to read at. * @return The character at that position, and modifies the cursor to * prepare for the next read. If the source is exhausted a zero is returned. * @exception ParserException If an IOException on the underlying source * occurs, or an attemp is made to read characters in the future (the * cursor position is ahead of the underlying stream) */ public char getCharacter (Cursor cursor) throws ParserException { int i; char ret; i = cursor.getPosition (); if (mSource.offset () < i) // hmmm, we could skip ahead, but then what about the EOL index throw new ParserException ( "attempt to read future characters from source " + i + " > " + mSource.offset ()); else if (mSource.offset () == i) try { i = mSource.read (); if (Source.EOF == i) ret = EOF; else { ret = (char)i; cursor.advance (); } } catch (IOException ioe) { throw new ParserException ( "problem reading a character at position " + cursor.getPosition (), ioe); } else { // historic read try { ret = mSource.getCharacter (i); } catch (IOException ioe) { throw new ParserException ( "can't read a character at position " + i, ioe); } cursor.advance (); } // handle \r if ('\r' == ret) { // switch to single character EOL ret = '\n'; // check for a \n in the next position if (mSource.offset () == cursor.getPosition ()) try { i = mSource.read (); if (Source.EOF == i) { // do nothing } else if ('\n' == (char)i) cursor.advance (); else try { mSource.unread (); } catch (IOException ioe) { throw new ParserException ( "can't unread a character at position " + cursor.getPosition (), ioe); } } catch (IOException ioe) { throw new ParserException ( "problem reading a character at position " + cursor.getPosition (), ioe); } else try { if ('\n' == mSource.getCharacter (cursor.getPosition ())) cursor.advance (); } catch (IOException ioe) { throw new ParserException ( "can't read a character at position " + cursor.getPosition (), ioe); } } if ('\n' == ret) // update the EOL index in any case mIndex.add (cursor); return (ret); } /** * Get the current encoding being used. * @return The encoding used to convert characters. */ public String getEncoding () { return (getSource ().getEncoding ()); } /** * Begins reading from the source with the given character set. * If the current encoding is the same as the requested encoding, * this method is a no-op. Otherwise any subsequent characters read from * this page will have been decoded using the given character set.

    * Some magic happens here to obtain this result if characters have already * been consumed from this page. * Since a Reader cannot be dynamically altered to use a different character * set, the underlying stream is reset, a new Source is constructed * and a comparison made of the characters read so far with the newly * read characters up to the current position. * If a difference is encountered, or some other problem occurs, * an exception is thrown. * @param character_set The character set to use to convert bytes into * characters. * @exception ParserException If a character mismatch occurs between * characters already provided and those that would have been returned * had the new character set been in effect from the beginning. An * exception is also thrown if the underlying stream won't put up with * these shenanigans. */ public void setEncoding (String character_set) throws ParserException { getSource ().setEncoding (character_set); } /** * Build a URL from the link and base provided. * @return An absolute URL. * @param link The (relative) URI. * @param base The base URL of the page, either from the <BASE> tag * or, if none, the URL the page is being fetched from. * @exception MalformedURLException If creating the URL fails. */ public URL constructUrl (String link, String base) throws MalformedURLException { String path; boolean modified; boolean absolute; int index; URL url; // constructed URL combining relative link and base url = new URL (new URL (base), link); path = url.getFile (); modified = false; absolute = link.startsWith ("/"); if (!absolute) { // we prefer to fix incorrect relative links // this doesn't fix them all, just the ones at the start while (path.startsWith ("/.")) { if (path.startsWith ("/../")) { path = path.substring (3); modified = true; } else if (path.startsWith ("/./") || path.startsWith("/.")) { path = path.substring (2); modified = true; } else break; } } // fix backslashes while (-1 != (index = path.indexOf ("/\\"))) { path = path.substring (0, index + 1) + path.substring (index + 2); modified = true; } if (modified) url = new URL (url, path); return (url); } /** * Create an absolute URL from a relative link. * @param link The reslative portion of a URL. * @return The fully qualified URL or the original link if it was absolute * already or a failure occured. */ public String getAbsoluteURL (String link) { String base; URL url; String ret; if ((null == link) || ("".equals (link))) ret = ""; else try { base = getBaseUrl (); if (null == base) base = getUrl (); if (null == base) ret = link; else { url = constructUrl (link, base); ret = url.toExternalForm (); } } catch (MalformedURLException murle) { ret = link; } return (ret); } /** * Get the line number for a cursor. * @param cursor The character offset into the page. * @return The line number the character is in. */ public int row (Cursor cursor) { return (mIndex.row (cursor)); } /** * Get the line number for a cursor. * @param position The character offset into the page. * @return The line number the character is in. */ public int row (int position) { return (mIndex.row (position)); } /** * Get the column number for a cursor. * @param cursor The character offset into the page. * @return The character offset into the line this cursor is on. */ public int column (Cursor cursor) { return (mIndex.column (cursor)); } /** * Get the column number for a cursor. * @param position The character offset into the page. * @return The character offset into the line this cursor is on. */ public int column (int position) { return (mIndex.column (position)); } /** * Get the text identified by the given limits. * @param start The starting position, zero based. * @param end The ending position * (exclusive, i.e. the character at the ending position is not included), * zero based. * @return The text from start to end. * @see #getText(StringBuffer, int, int) * @exception IllegalArgumentException If an attempt is made to get * characters ahead of the current source offset (character position). */ public String getText (int start, int end) throws IllegalArgumentException { String ret; try { ret = mSource.getString (start, end - start); } catch (IOException ioe) { throw new IllegalArgumentException ( "can't get the " + (end - start) + "characters at position " + start + " - " + ioe.getMessage ()); } return (ret); } /** * Put the text identified by the given limits into the given buffer. * @param buffer The accumulator for the characters. * @param start The starting position, zero based. * @param end The ending position * (exclusive, i.e. the character at the ending position is not included), * zero based. * @exception IllegalArgumentException If an attempt is made to get * characters ahead of the current source offset (character position). */ public void getText (StringBuilder buffer, int start, int end) throws IllegalArgumentException { int length; if ((mSource.offset () < start) || (mSource.offset () < end)) throw new IllegalArgumentException ( "attempt to extract future characters from source" + start + "|" + end + " > " + mSource.offset ()); if (end < start) { length = end; end = start; start = length; } length = end - start; try { mSource.getCharacters (buffer, start, length); } catch (IOException ioe) { throw new IllegalArgumentException ( "can't get the " + (end - start) + "characters at position " + start + " - " + ioe.getMessage ()); } } /** * Get all text read so far from the source. * @return The text from the source. * @see #getText(StringBuffer) */ public String getText () { return (getText (0, mSource.offset ())); } /** * Put all text read so far from the source into the given buffer. * @param buffer The accumulator for the characters. * @see #getText(StringBuffer,int,int) */ public void getText (StringBuilder buffer) { getText (buffer, 0, mSource.offset ()); } /** * Put the text identified by the given limits into the given array at the specified offset. * @param array The array of characters. * @param offset The starting position in the array where characters are to be placed. * @param start The starting position, zero based. * @param end The ending position * (exclusive, i.e. the character at the ending position is not included), * zero based. * @exception IllegalArgumentException If an attempt is made to get * characters ahead of the current source offset (character position). */ public void getText (char[] array, int offset, int start, int end) throws IllegalArgumentException { int length; if ((mSource.offset () < start) || (mSource.offset () < end)) throw new IllegalArgumentException ("attempt to extract future characters from source"); if (end < start) { // swap length = end; end = start; start = length; } length = end - start; try { mSource.getCharacters (array, offset, start, end); } catch (IOException ioe) { throw new IllegalArgumentException ( "can't get the " + (end - start) + "characters at position " + start + " - " + ioe.getMessage ()); } } /** * Get the text line the position of the cursor lies on. * @param cursor The position to calculate for. * @return The contents of the URL or file corresponding to the line number * containg the cursor position. */ public String getLine (Cursor cursor) { int line; int size; int start; int end; line = row (cursor); size = mIndex.size (); if (line < size) { start = mIndex.elementAt (line); line++; if (line <= size) end = mIndex.elementAt (line); else end = mSource.offset (); } else // current line { start = mIndex.elementAt (line - 1); end = mSource.offset (); } return (getText (start, end)); } /** * Get the text line the position of the cursor lies on. * @param position The position to calculate for. * @return The contents of the URL or file corresponding to the line number * containg the cursor position. */ public String getLine (int position) { return (getLine (new Cursor (this, position))); } /** * Display some of this page as a string. * @return The last few characters the source read in. */ public String toString () { StringBuilder buffer; int start; String ret; if (mSource.offset () > 0) { buffer = new StringBuilder (43); start = mSource.offset () - 40; if (0 > start) start = 0; else buffer.append ("..."); getText (buffer, start, mSource.offset ()); ret = buffer.toString (); } else ret = super.toString (); return (ret); } }





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