org.htmlunit.util

Class EncodingSniffer

java.lang.Object

org.htmlunit.util.EncodingSniffer

public final class EncodingSniffer
extends Object

Sniffs encoding settings from HTML, XML or other content. The HTML encoding sniffing algorithm is based on the HTML5 encoding sniffing algorithm.

Author:

Daniel Gredler, Ahmed Ashour, Ronald Brill, Lai Quang Duong

Method Summary

Modifier and Type	Method and Description
static Charset	extractEncodingFromContentType(String s) Extracts an encoding from the specified Content-Type value using the IETF algorithm; if no encoding is found, this method returns null.
static Charset	sniffEncoding(List<NameValuePair> headers, InputStream content) Deprecated. as of version 4.0.0; depending on the content use sniffEncodingFromMetaTag(InputStream), sniffEncodingFromXmlDeclaration(InputStream), or sniffEncodingFromCssDeclaration(InputStream) instead
static Charset	sniffEncodingFromCssDeclaration(InputStream is) Parses and returns the charset declaration at the start of a css file if any, otherwise returns null.
static Charset	sniffEncodingFromHttpHeaders(List<NameValuePair> headers) Deprecated. as of version 4.0.0; method will be removed without replacement
static Charset	sniffEncodingFromMetaTag(InputStream is) Attempts to sniff an encoding from an HTML meta tag in the specified byte array.
static Charset	sniffEncodingFromXmlDeclaration(InputStream is) Searches the specified XML content for an XML declaration and returns the encoding if found, otherwise returns null.
static Charset	sniffHtmlEncoding(List<NameValuePair> headers, InputStream content) Deprecated. as of version 4.0.0; depending on the content use sniffEncodingFromMetaTag(InputStream), sniffEncodingFromXmlDeclaration(InputStream), or sniffEncodingFromCssDeclaration(InputStream) instead
static Charset	sniffUnknownContentTypeEncoding(List<NameValuePair> headers, InputStream content) Deprecated. as of version 4.0.0; depending on the content use sniffEncodingFromMetaTag(InputStream), sniffEncodingFromXmlDeclaration(InputStream), or sniffEncodingFromCssDeclaration(InputStream) instead
static Charset	sniffXmlEncoding(List<NameValuePair> headers, InputStream content) Deprecated. as of version 4.0.0; depending on the content use sniffEncodingFromMetaTag(InputStream), sniffEncodingFromXmlDeclaration(InputStream), or sniffEncodingFromCssDeclaration(InputStream) instead
static Charset	toCharset(String charsetName) Returns Charset if the specified charset name is supported on this platform.
static String	translateEncodingLabel(Charset encodingLabel) Deprecated. as of version 4.0.0; method will be removed without replacement
static String	translateEncodingLabel(String encodingLabel) Translates the given encoding label into a normalized form according to Reference.

Methods inherited from class java.lang.Object

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

Method Detail

sniffEncoding

@Deprecated
public static Charset sniffEncoding(List<NameValuePair> headers,
                                                 InputStream content)
                                          throws IOException

Deprecated. as of version 4.0.0; depending on the content use sniffEncodingFromMetaTag(InputStream), sniffEncodingFromXmlDeclaration(InputStream), or sniffEncodingFromCssDeclaration(InputStream) instead

If the specified content is HTML content, this method sniffs encoding settings from the specified HTML content and/or the corresponding HTTP headers based on the HTML5 encoding sniffing algorithm.

If the specified content is XML content, this method sniffs encoding settings from the specified XML content and/or the corresponding HTTP headers using a custom algorithm.

Otherwise, this method sniffs encoding settings from the specified content of unknown type by looking for Content-Type information in the HTTP headers and Byte Order Mark information in the content.

Note that if an encoding is found but it is not supported on the current platform, this method returns null, as if no encoding had been found.

Parameters:

headers - the HTTP response headers sent back with the content to be sniffed

content - the content to be sniffed

Returns:

the encoding sniffed from the specified content and/or the corresponding HTTP headers, or null if the encoding could not be determined

Throws:

IOException - if an IO error occurs

sniffHtmlEncoding

@Deprecated
public static Charset sniffHtmlEncoding(List<NameValuePair> headers,
                                                     InputStream content)
                                              throws IOException

Deprecated. as of version 4.0.0; depending on the content use sniffEncodingFromMetaTag(InputStream), sniffEncodingFromXmlDeclaration(InputStream), or sniffEncodingFromCssDeclaration(InputStream) instead

Sniffs encoding settings from the specified HTML content and/or the corresponding HTTP headers based on the HTML5 encoding sniffing algorithm.

Note that if an encoding is found but it is not supported on the current platform, this method returns null, as if no encoding had been found.

Parameters:

headers - the HTTP response headers sent back with the HTML content to be sniffed

content - the HTML content to be sniffed

Returns:

the encoding sniffed from the specified HTML content and/or the corresponding HTTP headers, or null if the encoding could not be determined

Throws:

IOException - if an IO error occurs

sniffXmlEncoding

@Deprecated
public static Charset sniffXmlEncoding(List<NameValuePair> headers,
                                                    InputStream content)
                                             throws IOException

Deprecated. as of version 4.0.0; depending on the content use sniffEncodingFromMetaTag(InputStream), sniffEncodingFromXmlDeclaration(InputStream), or sniffEncodingFromCssDeclaration(InputStream) instead

Sniffs encoding settings from the specified XML content and/or the corresponding HTTP headers using a custom algorithm.

Note that if an encoding is found but it is not supported on the current platform, this method returns null, as if no encoding had been found.

Parameters:

headers - the HTTP response headers sent back with the XML content to be sniffed

content - the XML content to be sniffed

Returns:

the encoding sniffed from the specified XML content and/or the corresponding HTTP headers, or null if the encoding could not be determined

Throws:

IOException - if an IO error occurs

sniffUnknownContentTypeEncoding

@Deprecated
public static Charset sniffUnknownContentTypeEncoding(List<NameValuePair> headers,
                                                                   InputStream content)
                                                            throws IOException

Deprecated. as of version 4.0.0; depending on the content use sniffEncodingFromMetaTag(InputStream), sniffEncodingFromXmlDeclaration(InputStream), or sniffEncodingFromCssDeclaration(InputStream) instead

Sniffs encoding settings from the specified content of unknown type by looking for Content-Type information in the HTTP headers and Byte Order Mark information in the content.

Note that if an encoding is found but it is not supported on the current platform, this method returns null, as if no encoding had been found.

Parameters:

headers - the HTTP response headers sent back with the content to be sniffed

content - the content to be sniffed

Returns:

the encoding sniffed from the specified content and/or the corresponding HTTP headers, or null if the encoding could not be determined

Throws:

IOException - if an IO error occurs

sniffEncodingFromHttpHeaders

@Deprecated
public static Charset sniffEncodingFromHttpHeaders(List<NameValuePair> headers)

Deprecated. as of version 4.0.0; method will be removed without replacement

Attempts to sniff an encoding from the specified HTTP headers.

Parameters:

headers - the HTTP headers to examine

Returns:

the encoding sniffed from the specified HTTP headers, or null if the encoding could not be determined

sniffEncodingFromMetaTag

public static Charset sniffEncodingFromMetaTag(InputStream is)
                                        throws IOException

Attempts to sniff an encoding from an HTML meta tag in the specified byte array.

Parameters:

is - the content stream to check for an HTML meta tag

Returns:

the encoding sniffed from the specified bytes, or null if the encoding could not be determined

Throws:

IOException - if an IO error occurs

extractEncodingFromContentType

public static Charset extractEncodingFromContentType(String s)

Extracts an encoding from the specified Content-Type value using the IETF algorithm; if no encoding is found, this method returns null.

Parameters:

s - the Content-Type value to search for an encoding

Returns:

the encoding found in the specified Content-Type value, or null if no encoding was found

sniffEncodingFromXmlDeclaration

public static Charset sniffEncodingFromXmlDeclaration(InputStream is)
                                               throws IOException

Searches the specified XML content for an XML declaration and returns the encoding if found, otherwise returns null.

Parameters:

is - the content stream to check for the charset declaration

Returns:

the encoding of the specified XML content, or null if it could not be determined

Throws:

IOException - if an IO error occurs

sniffEncodingFromCssDeclaration

public static Charset sniffEncodingFromCssDeclaration(InputStream is)
                                               throws IOException

Parses and returns the charset declaration at the start of a css file if any, otherwise returns null.

e.g.

@charset "UTF-8"

Parameters:

is - the input stream to parse

Returns:

the charset declaration at the start of a css file if any, otherwise returns null.

Throws:

IOException - if an IO error occurs

toCharset

public static Charset toCharset(String charsetName)

Returns Charset if the specified charset name is supported on this platform.

Parameters:

charsetName - the charset name to check

Returns:

Charset if the specified charset name is supported on this platform

translateEncodingLabel

@Deprecated
public static String translateEncodingLabel(Charset encodingLabel)

Deprecated. as of version 4.0.0; method will be removed without replacement

Translates the given encoding label into a normalized form according to Reference.

Parameters:

encodingLabel - the label to translate

Returns:

the normalized encoding name or null if not found

translateEncodingLabel

public static String translateEncodingLabel(String encodingLabel)

Translates the given encoding label into a normalized form according to Reference.

Parameters:

encodingLabel - the label to translate

Returns:

the normalized encoding name or null if not found