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// ScraperInputStream.java
// (C) 2005, 2006 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 2005 on http://www.anomic.de
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $LastChangedDate$
// $LastChangedRevision$
// $LastChangedBy$
//
// LICENSE
//
// 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.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
package de.anomic.document.parser.html;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import java.util.Properties;
import net.yacy.kelondro.data.meta.DigestURI;
public class ScraperInputStream extends InputStream implements ScraperListener {
private static final int MODE_PRESCAN = 0;
private static final int MODE_PRESCAN_FINISHED = 1;
private int mode = 1;
private static final long preBufferSize = 4096;
private long preRead = 0;
private final BufferedInputStream bufferedIn;
private String detectedCharset;
private boolean charsetChanged = false;
private boolean endOfHead = false;
private Reader reader;
private Writer writer;
public ScraperInputStream(
final InputStream inStream,
final String inputStreamCharset,
final DigestURI rooturl,
final Transformer transformer,
final boolean passbyIfBinarySuspect
) {
// create a input stream for buffereing
this.bufferedIn = new BufferedInputStream(inStream,(int) preBufferSize);
this.bufferedIn.mark((int) preBufferSize);
final ContentScraper scraper = new ContentScraper(rooturl);
scraper.registerHtmlFilterEventListener(this);
try {
this.reader = new InputStreamReader(this,inputStreamCharset);
} catch (UnsupportedEncodingException e) {
try {
this.reader = new InputStreamReader(this, "UTF-8");
} catch (UnsupportedEncodingException e1) {
// how is that possible?
this.reader = new InputStreamReader(this);
}
}
this.writer = new TransformerWriter(null,null,scraper,transformer,passbyIfBinarySuspect);
}
private static String extractCharsetFromMimetypeHeader(final String mimeType) {
if (mimeType == null) return null;
final String[] parts = mimeType.split(";");
if (parts == null || parts.length <= 1) return null;
for (int i=1; i < parts.length; i++) {
final String param = parts[i].trim();
if (param.startsWith("charset=")) {
String charset = param.substring("charset=".length()).trim();
if (charset.startsWith("\"") || charset.startsWith("'")) charset = charset.substring(1);
if (charset.endsWith("\"") || charset.endsWith("'")) charset = charset.substring(0,charset.length()-1);
return charset.trim();
}
}
return null;
}
public void scrapeTag0(final String tagname, final Properties tagopts) {
if (tagname == null || tagname.length() == 0) return;
if (tagname.equalsIgnoreCase("meta")) {
if (tagopts.containsKey("http-equiv")) {
final String value = tagopts.getProperty("http-equiv");
if (value.equalsIgnoreCase("Content-Type")) {
// parse lines like <meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">
final String contentType = tagopts.getProperty("content","");
this.detectedCharset = extractCharsetFromMimetypeHeader(contentType);
if (this.detectedCharset != null && this.detectedCharset.length() > 0) {
this.charsetChanged = true;
} else if (tagopts.containsKey("charset")) {
// sometimes the charset property is configured as extra attribut. try it ...
this.detectedCharset = tagopts.getProperty("charset");
this.charsetChanged = true;
}
}
}
}
}
public void scrapeTag1(final String tagname, final Properties tagopts, final char[] text) {
if (tagname == null || tagname.length() == 0) return;
if (tagname.equalsIgnoreCase("head")) {
this.endOfHead = true;
}
}
public String detectCharset() throws IOException {
this.mode = MODE_PRESCAN;
// loop until we have detected the header element or the charset data
int c;
while ((c = this.reader.read())!= -1) {
this.writer.write(c);
if (this.charsetChanged) break; // thats enough
}
// free writer
this.writer = null;
// don't close writer here, otherwise it will shutdown our source stream
// reset the buffer if not already done
if (this.mode != MODE_PRESCAN_FINISHED) {
this.mode++;
this.bufferedIn.reset();
}
// return scanning result
return (this.charsetChanged) ? this.detectedCharset : null;
}
public int read() throws IOException {
// mode 0 is called from within the detectCharset function
if (this.mode == MODE_PRESCAN) {
if (this.endOfHead || this.charsetChanged || this.preRead >= preBufferSize - 1) {
return -1;
}
this.preRead++;
}
return this.bufferedIn.read();
}
}
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