/*
* @(#)Charset.java 1.54 08/04/07
*
* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.nio.charset;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.spi.CharsetProvider;
import java.security.AccessController;
import java.security.AccessControlException;
import java.security.PrivilegedAction;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Locale;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;
import sun.misc.ASCIICaseInsensitiveComparator;
import sun.misc.Service;
import sun.misc.ServiceConfigurationError;
import sun.nio.cs.StandardCharsets;
import sun.nio.cs.ThreadLocalCoders;
import sun.security.action.GetPropertyAction;
/**
* A named mapping between sequences of sixteen-bit Unicode <a
* href="../../lang/Character.html#unicode">code units</a> and sequences of
* bytes. This class defines methods for creating decoders and encoders and
* for retrieving the various names associated with a charset. Instances of
* this class are immutable.
*
* <p> This class also defines static methods for testing whether a particular
* charset is supported, for locating charset instances by name, and for
* constructing a map that contains every charset for which support is
* available in the current Java virtual machine. Support for new charsets can
* be added via the service-provider interface defined in the {@link
* java.nio.charset.spi.CharsetProvider} class.
*
* <p> All of the methods defined in this class are safe for use by multiple
* concurrent threads.
*
*
* <a name="names"><a name="charenc">
* <h4>Charset names</h4>
*
* <p> Charsets are named by strings composed of the following characters:
*
* <ul>
*
* <li> The uppercase letters <tt>'A'</tt> through <tt>'Z'</tt>
* (<tt>'\u0041'</tt> through <tt>'\u005a'</tt>),
*
* <li> The lowercase letters <tt>'a'</tt> through <tt>'z'</tt>
* (<tt>'\u0061'</tt> through <tt>'\u007a'</tt>),
*
* <li> The digits <tt>'0'</tt> through <tt>'9'</tt>
* (<tt>'\u0030'</tt> through <tt>'\u0039'</tt>),
*
* <li> The dash character <tt>'-'</tt>
* (<tt>'\u002d'</tt>, <small>HYPHEN-MINUS</small>),
*
* <li> The period character <tt>'.'</tt>
* (<tt>'\u002e'</tt>, <small>FULL STOP</small>),
*
* <li> The colon character <tt>':'</tt>
* (<tt>'\u003a'</tt>, <small>COLON</small>), and
*
* <li> The underscore character <tt>'_'</tt>
* (<tt>'\u005f'</tt>, <small>LOW LINE</small>).
*
* </ul>
*
* A charset name must begin with either a letter or a digit. The empty string
* is not a legal charset name. Charset names are not case-sensitive; that is,
* case is always ignored when comparing charset names. Charset names
* generally follow the conventions documented in <a
* href="http://ietf.org/rfc/rfc2278.txt"><i>RFC 2278: IANA Charset
* Registration Procedures</i></a>.
*
* <p> Every charset has a <i>canonical name</i> and may also have one or more
* <i>aliases</i>. The canonical name is returned by the {@link #name() name} method
* of this class. Canonical names are, by convention, usually in upper case.
* The aliases of a charset are returned by the {@link #aliases() aliases}
* method.
*
* <a name="hn">
*
* <p> Some charsets have an <i>historical name</i> that is defined for
* compatibility with previous versions of the Java platform. A charset's
* historical name is either its canonical name or one of its aliases. The
* historical name is returned by the <tt>getEncoding()</tt> methods of the
* {@link java.io.InputStreamReader#getEncoding InputStreamReader} and {@link
* java.io.OutputStreamWriter#getEncoding OutputStreamWriter} classes.
*
* <a name="iana">
*
* <p> If a charset listed in the <a
* href="http://www.iana.org/assignments/character-sets"><i>IANA Charset
* Registry</i></a> is supported by an implementation of the Java platform then
* its canonical name must be the name listed in the registry. Many charsets
* are given more than one name in the registry, in which case the registry
* identifies one of the names as <i>MIME-preferred</i>. If a charset has more
* than one registry name then its canonical name must be the MIME-preferred
* name and the other names in the registry must be valid aliases. If a
* supported charset is not listed in the IANA registry then its canonical name
* must begin with one of the strings <tt>"X-"</tt> or <tt>"x-"</tt>.
*
* <p> The IANA charset registry does change over time, and so the canonical
* name and the aliases of a particular charset may also change over time. To
* ensure compatibility it is recommended that no alias ever be removed from a
* charset, and that if the canonical name of a charset is changed then its
* previous canonical name be made into an alias.
*
*
* <h4>Standard charsets</h4>
*
* <p> Every implementation of the Java platform is required to support the
* following standard charsets. Consult the release documentation for your
* implementation to see if any other charsets are supported. The behavior
* of such optional charsets may differ between implementations.
*
* <blockquote><table width="80%" summary="Description of standard charsets">
* <tr><th><p align="left">Charset</p></th><th><p align="left">Description</p></th></tr>
* <tr><td valign=top><tt>US-ASCII</tt></td>
* <td>Seven-bit ASCII, a.k.a. <tt>ISO646-US</tt>,
* a.k.a. the Basic Latin block of the Unicode character set</td></tr>
* <tr><td valign=top><tt>ISO-8859-1 </tt></td>
* <td>ISO Latin Alphabet No. 1, a.k.a. <tt>ISO-LATIN-1</tt></td></tr>
* <tr><td valign=top><tt>UTF-8</tt></td>
* <td>Eight-bit UCS Transformation Format</td></tr>
* <tr><td valign=top><tt>UTF-16BE</tt></td>
* <td>Sixteen-bit UCS Transformation Format,
* big-endian byte order</td></tr>
* <tr><td valign=top><tt>UTF-16LE</tt></td>
* <td>Sixteen-bit UCS Transformation Format,
* little-endian byte order</td></tr>
* <tr><td valign=top><tt>UTF-16</tt></td>
* <td>Sixteen-bit UCS Transformation Format,
* byte order identified by an optional byte-order mark</td></tr>
* </table></blockquote>
*
* <p> The <tt>UTF-8</tt> charset is specified by <a
* href="http://ietf.org/rfc/rfc2279.txt"><i>RFC 2279</i></a>; the
* transformation format upon which it is based is specified in
* Amendment 2 of ISO 10646-1 and is also described in the <a
* href="http://www.unicode.org/unicode/standard/standard.html"><i>Unicode
* Standard</i></a>.
*
* <p> The <tt>UTF-16</tt> charsets are specified by <a
* href="http://ietf.org/rfc/rfc2781.txt"><i>RFC 2781</i></a>; the
* transformation formats upon which they are based are specified in
* Amendment 1 of ISO 10646-1 and are also described in the <a
* href="http://www.unicode.org/unicode/standard/standard.html"><i>Unicode
* Standard</i></a>.
*
* <p> The <tt>UTF-16</tt> charsets use sixteen-bit quantities and are
* therefore sensitive to byte order. In these encodings the byte order of a
* stream may be indicated by an initial <i>byte-order mark</i> represented by
* the Unicode character <tt>'\uFEFF'</tt>. Byte-order marks are handled
* as follows:
*
* <ul>
*
* <li><p> When decoding, the <tt>UTF-16BE</tt> and <tt>UTF-16LE</tt>
* charsets ignore byte-order marks; when encoding, they do not write
* byte-order marks. </p></li>
*
* <li><p> When decoding, the <tt>UTF-16</tt> charset interprets a byte-order
* mark to indicate the byte order of the stream but defaults to big-endian
* if there is no byte-order mark; when encoding, it uses big-endian byte
* order and writes a big-endian byte-order mark. </p></li>
*
* </ul>
*
* In any case, when a byte-order mark is read at the beginning of a decoding
* operation it is omitted from the resulting sequence of characters. Byte
* order marks occuring after the first element of an input sequence are not
* omitted since the same code is used to represent <small>ZERO-WIDTH
* NON-BREAKING SPACE</small>.
*
* <p> Every instance of the Java virtual machine has a default charset, which
* may or may not be one of the standard charsets. The default charset is
* determined during virtual-machine startup and typically depends upon the
* locale and charset being used by the underlying operating system. </p>
*
*
* <h4>Terminology</h4>
*
* <p> The name of this class is taken from the terms used in <a
* href="http://ietf.org/rfc/rfc2278.txt""><i>RFC 2278</i></a>. In that
* document a <i>charset</i> is defined as the combination of a coded character
* set and a character-encoding scheme.
*
* <p> A <i>coded character set</i> is a mapping between a set of abstract
* characters and a set of integers. US-ASCII, ISO 8859-1,
* JIS X 0201, and full Unicode, which is the same as
* ISO 10646-1, are examples of coded character sets.
*
* <p> A <i>character-encoding scheme</i> is a mapping between a coded
* character set and a set of octet (eight-bit byte) sequences. UTF-8, UCS-2,
* UTF-16, ISO 2022, and EUC are examples of character-encoding schemes.
* Encoding schemes are often associated with a particular coded character set;
* UTF-8, for example, is used only to encode Unicode. Some schemes, however,
* are associated with multiple character sets; EUC, for example, can be used
* to encode characters in a variety of Asian character sets.
*
* <p> When a coded character set is used exclusively with a single
* character-encoding scheme then the corresponding charset is usually named
* for the character set; otherwise a charset is usually named for the encoding
* scheme and, possibly, the locale of the character sets that it supports.
* Hence <tt>US-ASCII</tt> is the name of the charset for US-ASCII while
* <tt>EUC-JP</tt> is the name of the charset that encodes the
* JIS X 0201, JIS X 0208, and JIS X 0212
* character sets.
*
* <p> The native character encoding of the Java programming language is
* UTF-16. A charset in the Java platform therefore defines a mapping between
* sequences of sixteen-bit UTF-16 code units and sequences of bytes. </p>
*
*
* @author Mark Reinhold
* @author JSR-51 Expert Group
* @version 1.54, 08/04/07
* @since 1.4
*
* @see CharsetDecoder
* @see CharsetEncoder
* @see java.nio.charset.spi.CharsetProvider
* @see java.lang.Character
*/
public abstract class Charset
implements Comparable<Charset>
{
/* -- Static methods -- */
private static volatile String bugLevel = null;
static boolean atBugLevel(String bl) { // package-private
if (bugLevel == null) {
if (!sun.misc.VM.isBooted())
return false;
java.security.PrivilegedAction pa =
new GetPropertyAction("sun.nio.cs.bugLevel");
String value = (String)AccessController.doPrivileged(pa);
bugLevel = (value != null) ? value : "";
}
return bugLevel.equals(bl);
}
/**
* Checks that the given string is a legal charset name. </p>
*
* @param s
* A purported charset name
*
* @throws IllegalCharsetNameException
* If the given name is not a legal charset name
*/
private static void checkName(String s) {
int n = s.length();
if (!atBugLevel("1.4")) {
if (n == 0)
throw new IllegalCharsetNameException(s);
}
for (int i = 0; i < n; i++) {
char c = s.charAt(i);
if (c >= 'A' && c <= 'Z') continue;
if (c >= 'a' && c <= 'z') continue;
if (c >= '0' && c <= '9') continue;
if (c == '-' && i != 0) continue;
if (c == ':' && i != 0) continue;
if (c == '_' && i != 0) continue;
if (c == '.' && i != 0) continue;
throw new IllegalCharsetNameException(s);
}
}
/* The standard set of charsets */
private static CharsetProvider standardProvider = new StandardCharsets();
// Cache of the most-recently-returned charsets,
// along with the names that were used to find them
//
private static volatile Object[] cache1 = null; // "Level 1" cache
private static volatile Object[] cache2 = null; // "Level 2" cache
private static void cache(String charsetName, Charset cs) {
cache2 = cache1;
cache1 = new Object[] { charsetName, cs };
}
// Creates an iterator that walks over the available providers, ignoring
// those whose lookup or instantiation causes a security exception to be
// thrown. Should be invoked with full privileges.
//
private static Iterator providers() {
return new Iterator() {
Class c = java.nio.charset.spi.CharsetProvider.class;
ClassLoader cl = ClassLoader.getSystemClassLoader();
Iterator i = Service.providers(c, cl);
Object next = null;
private boolean getNext() {
while (next == null) {
try {
if (!i.hasNext())
return false;
next = i.next();
} catch (ServiceConfigurationError sce) {
if (sce.getCause() instanceof SecurityException) {
// Ignore security exceptions
continue;
}
throw sce;
}
}
return true;
}
public boolean hasNext() {
return getNext();
}
public Object next() {
if (!getNext())
throw new NoSuchElementException();
Object n = next;
next = null;
return n;
}
public void remove() {
throw new UnsupportedOperationException();
}
};
}
// Thread-local gate to prevent recursive provider lookups
private static ThreadLocal gate = new ThreadLocal();
private static Charset lookupViaProviders(final String charsetName) {
// The runtime startup sequence looks up standard charsets as a
// consequence of the VM's invocation of System.initializeSystemClass
// in order to, e.g., set system properties and encode filenames. At
// that point the application class loader has not been initialized,
// however, so we can't look for providers because doing so will cause
// that loader to be prematurely initialized with incomplete
// information.
//
if (!sun.misc.VM.isBooted())
return null;
if (gate.get() != null)
// Avoid recursive provider lookups
return null;
try {
gate.set(gate);
return (Charset)AccessController
.doPrivileged(new PrivilegedAction() {
public Object run() {
for (Iterator i = providers(); i.hasNext();) {
CharsetProvider cp = (CharsetProvider)i.next();
Charset cs = cp.charsetForName(charsetName);
if (cs != null)
return cs;
}
return null;
}
});
} finally {
gate.set(null);
}
}
/* The extended set of charsets */
private static Object extendedProviderLock = new Object();
private static boolean extendedProviderProbed = false;
private static CharsetProvider extendedProvider = null;
private static void probeExtendedProvider() {
AccessController.doPrivileged(new PrivilegedAction() {
public Object run() {
try {
Class epc
= Class.forName("sun.nio.cs.ext.ExtendedCharsets");
extendedProvider = (CharsetProvider)epc.newInstance();
} catch (ClassNotFoundException x) {
// Extended charsets not available
// (charsets.jar not present)
} catch (InstantiationException x) {
throw new Error(x);
} catch (IllegalAccessException x) {
throw new Error(x);
}
return null;
}
});
}
private static Charset lookupExtendedCharset(String charsetName) {
CharsetProvider ecp = null;
synchronized (extendedProviderLock) {
if (!extendedProviderProbed) {
probeExtendedProvider();
extendedProviderProbed = true;
}
ecp = extendedProvider;
}
return (ecp != null) ? ecp.charsetForName(charsetName) : null;
}
private static Charset lookup(String charsetName) {
if (charsetName == null)
throw new IllegalArgumentException("Null charset name");
Object[] a;
if ((a = cache1) != null && charsetName.equals(a[0]))
return (Charset)a[1];
// We expect most programs to use one Charset repeatedly.
// We convey a hint to this effect to the VM by putting the
// level 1 cache miss code in a separate method.
return lookup2(charsetName);
}
private static Charset lookup2(String charsetName) {
Object[] a;
if ((a = cache2) != null && charsetName.equals(a[0])) {
cache2 = cache1;
cache1 = a;
return (Charset)a[1];
}
Charset cs;
if ((cs = standardProvider.charsetForName(charsetName)) != null ||
(cs = lookupExtendedCharset(charsetName)) != null ||
(cs = lookupViaProviders(charsetName)) != null)
{
cache(charsetName, cs);
return cs;
}
/* Only need to check the name if we didn't find a charset for it */
checkName(charsetName);
return null;
}
/**
* Tells whether the named charset is supported. </p>
*
* @param charsetName
* The name of the requested charset; may be either
* a canonical name or an alias
*
* @return <tt>true</tt> if, and only if, support for the named charset
* is available in the current Java virtual machine
*
* @throws IllegalCharsetNameException
* If the given charset name is illegal
*
* @throws IllegalArgumentException
* If the given <tt>charsetName</tt> is null
*/
public static boolean isSupported(String charsetName) {
return (lookup(charsetName) != null);
}
/**
* Returns a charset object for the named charset. </p>
*
* @param charsetName
* The name of the requested charset; may be either
* a canonical name or an alias
*
* @return A charset object for the named charset
*
* @throws IllegalCharsetNameException
* If the given charset name is illegal
*
* @throws IllegalArgumentException
* If the given <tt>charsetName</tt> is null
*
* @throws UnsupportedCharsetException
* If no support for the named charset is available
* in this instance of the Java virtual machine
*/
public static Charset forName(String charsetName) {
Charset cs = lookup(charsetName);
if (cs != null)
return cs;
throw new UnsupportedCharsetException(charsetName);
}
// Fold charsets from the given iterator into the given map, ignoring
// charsets whose names already have entries in the map.
//
private static void put(Iterator i, Map m) {
while (i.hasNext()) {
Charset cs = (Charset)i.next();
if (!m.containsKey(cs.name()))
m.put(cs.name(), cs);
}
}
/**
* Constructs a sorted map from canonical charset names to charset objects.
*
* <p> The map returned by this method will have one entry for each charset
* for which support is available in the current Java virtual machine. If
* two or more supported charsets have the same canonical name then the
* resulting map will contain just one of them; which one it will contain
* is not specified. </p>
*
* <p> The invocation of this method, and the subsequent use of the
* resulting map, may cause time-consuming disk or network I/O operations
* to occur. This method is provided for applications that need to
* enumerate all of the available charsets, for example to allow user
* charset selection. This method is not used by the {@link #forName
* forName} method, which instead employs an efficient incremental lookup
* algorithm.
*
* <p> This method may return different results at different times if new
* charset providers are dynamically made available to the current Java
* virtual machine. In the absence of such changes, the charsets returned
* by this method are exactly those that can be retrieved via the {@link
* #forName forName} method. </p>
*
* @return An immutable, case-insensitive map from canonical charset names
* to charset objects
*/
public static SortedMap<String,Charset> availableCharsets() {
return (SortedMap)AccessController
.doPrivileged(new PrivilegedAction() {
public Object run() {
TreeMap m = new TreeMap(ASCIICaseInsensitiveComparator.CASE_INSENSITIVE_ORDER);
put(standardProvider.charsets(), m);
for (Iterator i = providers(); i.hasNext();) {
CharsetProvider cp = (CharsetProvider)i.next();
put(cp.charsets(), m);
}
return Collections.unmodifiableSortedMap(m);
}
});
}
private static volatile Charset defaultCharset;
/**
* Returns the default charset of this Java virtual machine.
*
* <p> The default charset is determined during virtual-machine startup and
* typically depends upon the locale and charset of the underlying
* operating system.
*
* @return A charset object for the default charset
*
* @since 1.5
*/
public static Charset defaultCharset() {
if (defaultCharset == null) {
synchronized (Charset.class) {
java.security.PrivilegedAction pa =
new GetPropertyAction("file.encoding");
String csn = (String)AccessController.doPrivileged(pa);
Charset cs = lookup(csn);
if (cs != null)
defaultCharset = cs;
else
defaultCharset = forName("UTF-8");
}
}
return defaultCharset;
}
/* -- Instance fields and methods -- */
private final String name; // tickles a bug in oldjavac
private final String[] aliases; // tickles a bug in oldjavac
private Set aliasSet = null;
/**
* Initializes a new charset with the given canonical name and alias
* set. </p>
*
* @param canonicalName
* The canonical name of this charset
*
* @param aliases
* An array of this charset's aliases, or null if it has no aliases
*
* @throws IllegalCharsetNameException
* If the canonical name or any of the aliases are illegal
*/
protected Charset(String canonicalName, String[] aliases) {
checkName(canonicalName);
String[] as = (aliases == null) ? new String[0] : aliases;
for (int i = 0; i < as.length; i++)
checkName(as[i]);
this.name = canonicalName;
this.aliases = as;
}
/**
* Returns this charset's canonical name. </p>
*
* @return The canonical name of this charset
*/
public final String name() {
return name;
}
/**
* Returns a set containing this charset's aliases. </p>
*
* @return An immutable set of this charset's aliases
*/
public final Set<String> aliases() {
if (aliasSet != null)
return aliasSet;
int n = aliases.length;
HashSet hs = new HashSet(n);
for (int i = 0; i < n; i++)
hs.add(aliases[i]);
aliasSet = Collections.unmodifiableSet(hs);
return aliasSet;
}
/**
* Returns this charset's human-readable name for the default locale.
*
* <p> The default implementation of this method simply returns this
* charset's canonical name. Concrete subclasses of this class may
* override this method in order to provide a localized display name. </p>
*
* @return The display name of this charset in the default locale
*/
public String displayName() {
return name;
}
/**
* Tells whether or not this charset is registered in the <a
* href="http://www.iana.org/assignments/character-sets">IANA Charset
* Registry</a>. </p>
*
* @return <tt>true</tt> if, and only if, this charset is known by its
* implementor to be registered with the IANA
*/
public final boolean isRegistered() {
return !name.startsWith("X-") && !name.startsWith("x-");
}
/**
* Returns this charset's human-readable name for the given locale.
*
* <p> The default implementation of this method simply returns this
* charset's canonical name. Concrete subclasses of this class may
* override this method in order to provide a localized display name. </p>
*
* @param locale
* The locale for which the display name is to be retrieved
*
* @return The display name of this charset in the given locale
*/
public String displayName(Locale locale) {
return name;
}
/**
* Tells whether or not this charset contains the given charset.
*
* <p> A charset <i>C</i> is said to <i>contain</i> a charset <i>D</i> if,
* and only if, every character representable in <i>D</i> is also
* representable in <i>C</i>. If this relationship holds then it is
* guaranteed that every string that can be encoded in <i>D</i> can also be
* encoded in <i>C</i> without performing any replacements.
*
* <p> That <i>C</i> contains <i>D</i> does not imply that each character
* representable in <i>C</i> by a particular byte sequence is represented
* in <i>D</i> by the same byte sequence, although sometimes this is the
* case.
*
* <p> Every charset contains itself.
*
* <p> This method computes an approximation of the containment relation:
* If it returns <tt>true</tt> then the given charset is known to be
* contained by this charset; if it returns <tt>false</tt>, however, then
* it is not necessarily the case that the given charset is not contained
* in this charset.
*
* @return <tt>true</tt> if the given charset is contained in this charset
*/
public abstract boolean contains(Charset cs);
/**
* Constructs a new decoder for this charset. </p>
*
* @return A new decoder for this charset
*/
public abstract CharsetDecoder newDecoder();
/**
* Constructs a new encoder for this charset. </p>
*
* @return A new encoder for this charset
*
* @throws UnsupportedOperationException
* If this charset does not support encoding
*/
public abstract CharsetEncoder newEncoder();
/**
* Tells whether or not this charset supports encoding.
*
* <p> Nearly all charsets support encoding. The primary exceptions are
* special-purpose <i>auto-detect</i> charsets whose decoders can determine
* which of several possible encoding schemes is in use by examining the
* input byte sequence. Such charsets do not support encoding because
* there is no way to determine which encoding should be used on output.
* Implementations of such charsets should override this method to return
* <tt>false</tt>. </p>
*
* @return <tt>true</tt> if, and only if, this charset supports encoding
*/
public boolean canEncode() {
return true;
}
/**
* Convenience method that decodes bytes in this charset into Unicode
* characters.
*
* <p> An invocation of this method upon a charset <tt>cs</tt> returns the
* same result as the expression
*
* <pre>
* cs.newDecoder()
* .onMalformedInput(CodingErrorAction.REPLACE)
* .onUnmappableCharacter(CodingErrorAction.REPLACE)
* .decode(bb); </pre>
*
* except that it is potentially more efficient because it can cache
* decoders between successive invocations.
*
* <p> This method always replaces malformed-input and unmappable-character
* sequences with this charset's default replacement byte array. In order
* to detect such sequences, use the {@link
* CharsetDecoder#decode(java.nio.ByteBuffer)} method directly. </p>
*
* @param bb The byte buffer to be decoded
*
* @return A char buffer containing the decoded characters
*/
public final CharBuffer decode(ByteBuffer bb) {
try {
return ThreadLocalCoders.decoderFor(this)
.onMalformedInput(CodingErrorAction.REPLACE)
.onUnmappableCharacter(CodingErrorAction.REPLACE)
.decode(bb);
} catch (CharacterCodingException x) {
throw new Error(x); // Can't happen
}
}
/**
* Convenience method that encodes Unicode characters into bytes in this
* charset.
*
* <p> An invocation of this method upon a charset <tt>cs</tt> returns the
* same result as the expression
*
* <pre>
* cs.newEncoder()
* .onMalformedInput(CodingErrorAction.REPLACE)
* .onUnmappableCharacter(CodingErrorAction.REPLACE)
* .encode(bb); </pre>
*
* except that it is potentially more efficient because it can cache
* encoders between successive invocations.
*
* <p> This method always replaces malformed-input and unmappable-character
* sequences with this charset's default replacement string. In order to
* detect such sequences, use the {@link
* CharsetEncoder#encode(java.nio.CharBuffer)} method directly. </p>
*
* @param cb The char buffer to be encoded
*
* @return A byte buffer containing the encoded characters
*/
public final ByteBuffer encode(CharBuffer cb) {
try {
return ThreadLocalCoders.encoderFor(this)
.onMalformedInput(CodingErrorAction.REPLACE)
.onUnmappableCharacter(CodingErrorAction.REPLACE)
.encode(cb);
} catch (CharacterCodingException x) {
throw new Error(x); // Can't happen
}
}
/**
* Convenience method that encodes a string into bytes in this charset.
*
* <p> An invocation of this method upon a charset <tt>cs</tt> returns the
* same result as the expression
*
* <pre>
* cs.encode(CharBuffer.wrap(s)); </pre>
*
* @param str The string to be encoded
*
* @return A byte buffer containing the encoded characters
*/
public final ByteBuffer encode(String str) {
return encode(CharBuffer.wrap(str));
}
/**
* Compares this charset to another.
*
* <p> Charsets are ordered by their canonical names, without regard to
* case. </p>
*
* @param that
* The charset to which this charset is to be compared
*
* @return A negative integer, zero, or a positive integer as this charset
* is less than, equal to, or greater than the specified charset
*/
public final int compareTo(Charset that) {
return (name().compareToIgnoreCase(that.name()));
}
/**
* Computes a hashcode for this charset. </p>
*
* @return An integer hashcode
*/
public final int hashCode() {
return name().hashCode();
}
/**
* Tells whether or not this object is equal to another.
*
* <p> Two charsets are equal if, and only if, they have the same canonical
* names. A charset is never equal to any other type of object. </p>
*
* @return <tt>true</tt> if, and only if, this charset is equal to the
* given object
*/
public final boolean equals(Object ob) {
if (!(ob instanceof Charset))
return false;
if (this == ob)
return true;
return name.equals(((Charset)ob).name());
}
/**
* Returns a string describing this charset. </p>
*
* @return A string describing this charset
*/
public final String toString() {
return name();
}
}