com.gargoylesoftware.htmlunit.util

Class EncodingSniffer

java.lang.Object

com.gargoylesoftware.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

Method Summary

Modifier and Type	Method and Description
static Charset	sniffEncoding(List<NameValuePair> headers, InputStream content) 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.
static Charset	sniffEncodingFromHttpHeaders(List<NameValuePair> headers) Attempts to sniff an encoding from the specified HTTP headers.
static Charset	sniffHtmlEncoding(List<NameValuePair> headers, InputStream content) Sniffs encoding settings from the specified HTML content and/or the corresponding HTTP headers based on the HTML5 encoding sniffing algorithm.
static Charset	sniffUnknownContentTypeEncoding(List<NameValuePair> headers, InputStream content) 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.
static Charset	sniffXmlEncoding(List<NameValuePair> headers, InputStream content) Sniffs encoding settings from the specified XML content and/or the corresponding HTTP headers using a custom algorithm.
static Charset	toCharset(String charsetName) Returns Charset if the specified charset name is supported on this platform.
static String	translateEncodingLabel(Charset 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

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

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

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

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

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

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

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

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

public static Charset sniffEncodingFromHttpHeaders(List<NameValuePair> headers)

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

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

public static String translateEncodingLabel(Charset 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