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IDNA

public abstract class IDNA
extends Object

java.lang.Object
   ↳ android.icu.text.IDNA


Abstract base class for IDNA processing. See http://www.unicode.org/reports/tr46/ and http://www.ietf.org/rfc/rfc3490.txt

The IDNA class is not intended for public subclassing.

The non-static methods implement UTS #46 and IDNA2008. IDNA2008 is implemented according to UTS #46, see getUTS46Instance().

IDNA2003 is obsolete. The static methods implement IDNA2003. They are all deprecated.

IDNA2003 API Overview:

The static IDNA API methods implement the IDNA protocol as defined in the IDNA RFC. The draft defines 2 operations: ToASCII and ToUnicode. Domain labels containing non-ASCII code points are required to be processed by ToASCII operation before passing it to resolver libraries. Domain names that are obtained from resolver libraries are required to be processed by ToUnicode operation before displaying the domain name to the user. IDNA requires that implementations process input strings with Nameprep, which is a profile of Stringprep , and then with Punycode. Implementations of IDNA MUST fully implement Nameprep and Punycode; neither Nameprep nor Punycode are optional. The input and output of ToASCII and ToUnicode operations are Unicode and are designed to be chainable, i.e., applying ToASCII or ToUnicode operations multiple times to an input string will yield the same result as applying the operation once. ToUnicode(ToUnicode(ToUnicode...(ToUnicode(string)))) == ToUnicode(string) ToASCII(ToASCII(ToASCII...(ToASCII(string))) == ToASCII(string).

Summary

Nested classes

enum IDNA.Error

IDNA error bit set values. 

class IDNA.Info

Output container for IDNA processing errors. 

Constants

int CHECK_BIDI

IDNA option to check for whether the input conforms to the BiDi rules.

int CHECK_CONTEXTJ

IDNA option to check for whether the input conforms to the CONTEXTJ rules.

int CHECK_CONTEXTO

IDNA option to check for whether the input conforms to the CONTEXTO rules.

int DEFAULT

Default options value: None of the other options are set.

int NONTRANSITIONAL_TO_ASCII

IDNA option for nontransitional processing in ToASCII().

int NONTRANSITIONAL_TO_UNICODE

IDNA option for nontransitional processing in ToUnicode().

int USE_STD3_RULES

Option to check whether the input conforms to the STD3 ASCII rules, for example the restriction of labels to LDH characters (ASCII Letters, Digits and Hyphen-Minus).

Public methods

static IDNA getUTS46Instance(int options)

Returns an IDNA instance which implements UTS #46.

abstract StringBuilder labelToASCII(CharSequence label, StringBuilder dest, IDNA.Info info)

Converts a single domain name label into its ASCII form for DNS lookup.

abstract StringBuilder labelToUnicode(CharSequence label, StringBuilder dest, IDNA.Info info)

Converts a single domain name label into its Unicode form for human-readable display.

abstract StringBuilder nameToASCII(CharSequence name, StringBuilder dest, IDNA.Info info)

Converts a whole domain name into its ASCII form for DNS lookup.

abstract StringBuilder nameToUnicode(CharSequence name, StringBuilder dest, IDNA.Info info)

Converts a whole domain name into its Unicode form for human-readable display.

Inherited methods

Constants

CHECK_BIDI

added in API level 24
public static final int CHECK_BIDI

IDNA option to check for whether the input conforms to the BiDi rules. For use in static worker and factory methods.

This option is ignored by the IDNA2003 implementation. (IDNA2003 always performs a BiDi check.)

Constant Value: 4 (0x00000004)

CHECK_CONTEXTJ

added in API level 24
public static final int CHECK_CONTEXTJ

IDNA option to check for whether the input conforms to the CONTEXTJ rules. For use in static worker and factory methods.

This option is ignored by the IDNA2003 implementation. (The CONTEXTJ check is new in IDNA2008.)

Constant Value: 8 (0x00000008)

CHECK_CONTEXTO

added in API level 24
public static final int CHECK_CONTEXTO

IDNA option to check for whether the input conforms to the CONTEXTO rules. For use in static worker and factory methods.

This option is ignored by the IDNA2003 implementation. (The CONTEXTO check is new in IDNA2008.)

This is for use by registries for IDNA2008 conformance. UTS #46 does not require the CONTEXTO check.

Constant Value: 64 (0x00000040)

DEFAULT

added in API level 24
public static final int DEFAULT

Default options value: None of the other options are set. For use in static worker and factory methods.

Constant Value: 0 (0x00000000)

NONTRANSITIONAL_TO_ASCII

added in API level 24
public static final int NONTRANSITIONAL_TO_ASCII

IDNA option for nontransitional processing in ToASCII(). For use in static worker and factory methods.

By default, ToASCII() uses transitional processing.

This option is ignored by the IDNA2003 implementation. (This is only relevant for compatibility of newer IDNA implementations with IDNA2003.)

Constant Value: 16 (0x00000010)

NONTRANSITIONAL_TO_UNICODE

added in API level 24
public static final int NONTRANSITIONAL_TO_UNICODE

IDNA option for nontransitional processing in ToUnicode(). For use in static worker and factory methods.

By default, ToUnicode() uses transitional processing.

This option is ignored by the IDNA2003 implementation. (This is only relevant for compatibility of newer IDNA implementations with IDNA2003.)

Constant Value: 32 (0x00000020)

USE_STD3_RULES

added in API level 24
public static final int USE_STD3_RULES

Option to check whether the input conforms to the STD3 ASCII rules, for example the restriction of labels to LDH characters (ASCII Letters, Digits and Hyphen-Minus). For use in static worker and factory methods.

Constant Value: 2 (0x00000002)

Public methods

getUTS46Instance

added in API level 24
public static IDNA getUTS46Instance (int options)

Returns an IDNA instance which implements UTS #46. Returns an unmodifiable instance, owned by the caller. Cache it for multiple operations, and delete it when done. The instance is thread-safe, that is, it can be used concurrently.

UTS #46 defines Unicode IDNA Compatibility Processing, updated to the latest version of Unicode and compatible with both IDNA2003 and IDNA2008.

The worker functions use transitional processing, including deviation mappings, unless NONTRANSITIONAL_TO_ASCII or NONTRANSITIONAL_TO_UNICODE is used in which case the deviation characters are passed through without change.

Disallowed characters are mapped to U+FFFD.

Operations with the UTS #46 instance do not support the ALLOW_UNASSIGNED option.

By default, the UTS #46 implementation allows all ASCII characters (as valid or mapped). When the USE_STD3_RULES option is used, ASCII characters other than letters, digits, hyphen (LDH) and dot/full stop are disallowed and mapped to U+FFFD.

Parameters
options int: Bit set to modify the processing and error checking.

Returns
IDNA the UTS #46 IDNA instance, if successful

labelToASCII

added in API level 24
public abstract StringBuilder labelToASCII (CharSequence label, 
                StringBuilder dest, 
                IDNA.Info info)

Converts a single domain name label into its ASCII form for DNS lookup. If any processing step fails, then info.hasErrors() will be true and the result might not be an ASCII string. The label might be modified according to the types of errors. Labels with severe errors will be left in (or turned into) their Unicode form.

Parameters
label CharSequence: Input domain name label

dest StringBuilder: Destination string object

info IDNA.Info: Output container of IDNA processing details.

Returns
StringBuilder dest

labelToUnicode

added in API level 24
public abstract StringBuilder labelToUnicode (CharSequence label, 
                StringBuilder dest, 
                IDNA.Info info)

Converts a single domain name label into its Unicode form for human-readable display. If any processing step fails, then info.hasErrors() will be true. The label might be modified according to the types of errors.

Parameters
label CharSequence: Input domain name label

dest StringBuilder: Destination string object

info IDNA.Info: Output container of IDNA processing details.

Returns
StringBuilder dest

nameToASCII

added in API level 24
public abstract StringBuilder nameToASCII (CharSequence name, 
                StringBuilder dest, 
                IDNA.Info info)

Converts a whole domain name into its ASCII form for DNS lookup. If any processing step fails, then info.hasErrors() will be true and the result might not be an ASCII string. The domain name might be modified according to the types of errors. Labels with severe errors will be left in (or turned into) their Unicode form.

Parameters
name CharSequence: Input domain name

dest StringBuilder: Destination string object

info IDNA.Info: Output container of IDNA processing details.

Returns
StringBuilder dest

nameToUnicode

added in API level 24
public abstract StringBuilder nameToUnicode (CharSequence name, 
                StringBuilder dest, 
                IDNA.Info info)

Converts a whole domain name into its Unicode form for human-readable display. If any processing step fails, then info.hasErrors() will be true. The domain name might be modified according to the types of errors.

Parameters
name CharSequence: Input domain name

dest StringBuilder: Destination string object

info IDNA.Info: Output container of IDNA processing details.

Returns
StringBuilder dest