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https://issues.apache.org/jira/browse/NUTCH-25?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12514382
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Doug Cook commented on NUTCH-25:
--------------------------------
Oops, spoke to soon. On running a more extensive test, I saw quite a few
ArrayIndexOutOfBound errors coming from ICU4J. Most were for index 0, some were
not.
The index 0 ones seem explainable by passing in content that is too short (see:
http://bugs.icu-project.org/trac/ticket/5596). This was easily fixed. Then
there were problems from non-zero indices; I don't understand why these happen,
but in any case, they should not cause the entire fetch to fail, so I added a
try/catch around the call to ICU4J; failures will now fall back to the previous
methods (the response header or sniffing, as appropriate).
The new check follows. When this crawl finishes I will look for any more subtle
errors in my relevance tests.
String encoding = null;
if (minConfidence >= 0 && DETECTABLES.contains(getContentType()) &&
content.length > 4) {
detector.enableInputFilter(true);
detector.setText(content);
CharsetMatch match = null;
try {
match = detector.detect();
}
catch (Exception e) {}
if (LOG.isTraceEnabled()) {
LOG.trace("Detected: confidence="+match.getConfidence());
}
if (match != null && match.getConfidence() >= minConfidence)
encoding = match.getName();
}
if (encoding != null) {
metadata.set(Metadata.DETECTED_ENCODING, encoding);
}
}
> needs 'character encoding' detector
> -----------------------------------
>
> Key: NUTCH-25
> URL: https://issues.apache.org/jira/browse/NUTCH-25
> Project: Nutch
> Issue Type: Wish
> Reporter: Stefan Groschupf
> Priority: Trivial
> Attachments: NUTCH-25_draft.patch
>
>
> transferred from:
> http://sourceforge.net/tracker/index.php?func=detail&aid=995730&group_id=59548&atid=491356
> submitted by:
> Jungshik Shin
> this is a follow-up to bug 993380 (figure out 'charset'
> from the meta tag).
> Although we can cover a lot of ground using the 'C-T'
> header field in in the HTTP header and the
> corresponding meta tag in html documents (and in case
> of XML, we have to use a similar but a different
> 'parsing'), in the wild, there are a lot of documents
> without any information about the character encoding
> used. Browsers like Mozilla and search engines like
> Google use character encoding detectors to deal with
> these 'unlabelled' documents.
> Mozilla's character encoding detector is GPL/MPL'd and
> we might be able to port it to Java. Unfortunately,
> it's not fool-proof. However, along with some other
> heuristic used by Mozilla and elsewhere, it'll be
> possible to achieve a high rate of the detection.
> The following page has links to some other related pages.
> http://trainedmonkey.com/week/2004/26
> In addition to the character encoding detection, we
> also need to detect the language of a document, which
> is even harder and should be a separate bug (although
> it's related).
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