Package org.apache.tika.detect

Class BOMDetector

java.lang.Object

org.apache.tika.detect.BOMDetector

All Implemented Interfaces:

Serializable, SelfConfiguring, EncodingDetector

public class BOMDetector
extends Object
implements EncodingDetector

Encoding detector that identifies the character set from a byte-order mark (BOM) at the start of the stream. Returns a single EncodingResult.ResultType.DECLARATIVE result when a BOM is found — a BOM is an explicit in-band declaration of encoding and takes priority over all statistical or structural inference.

SPI-loaded first in the default encoding-detector chain so that BOM evidence reaches the meta arbiter (JunkFilterEncodingDetector) before any statistical detector runs. MojibusterEncodingDetector strips the BOM from its own probe independently to ensure consistent model inference (BOMs are excluded from training data).

Since:

Apache Tika 0.x (moved to org.apache.tika.detect in 4.0)

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
BOMDetector()

Method Summary

Modifier and Type	Method	Description
List<EncodingResult>	detect(TikaInputStream tis, Metadata metadata, ParseContext parseContext)	Detects the character encoding of the given text document.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

BOMDetector

public BOMDetector()

Method Details

detect

public List<EncodingResult> detect(TikaInputStream tis,
 Metadata metadata,
 ParseContext parseContext)
                            throws IOException

Description copied from interface: EncodingDetector

Detects the character encoding of the given text document.

Returns an empty list if the encoding cannot be determined. Returns a ranked list of candidates in descending confidence order otherwise. The first entry is always the best guess.

If the document input stream is not available, then the first argument may be null. Otherwise the detector may read bytes from the start of the stream to help in encoding detection. The given stream is guaranteed to support the mark feature and the detector is expected to mark the stream before reading any bytes from it, and to reset the stream before returning. The stream must not be closed by the detector.

The given input metadata is only read, not modified, by the detector.

Specified by:

detect in interface EncodingDetector

Parameters:

tis - text document input stream, or null

metadata - input metadata for the document

parseContext - the parse context

Returns:

ranked list of encoding results, empty if unknown; never null

Throws:

IOException - if the document input stream could not be read