Java example source code file (Encodings.java)
The Encodings.java Java example source code
/*
* reserved comment block
* DO NOT REMOVE OR ALTER!
*/
/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* $Id: Encodings.java,v 1.3 2005/09/28 13:49:04 pvedula Exp $
*/
package com.sun.org.apache.xml.internal.serializer;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import java.io.BufferedWriter;
import java.net.URL;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Properties;
import java.util.StringTokenizer;
import java.io.IOException;
import java.net.MalformedURLException;
import java.nio.charset.Charset;
import java.nio.charset.IllegalCharsetNameException;
import java.nio.charset.UnsupportedCharsetException;
import java.util.Collections;
import java.util.Map;
import java.util.Map.Entry;
import com.sun.org.apache.xalan.internal.utils.SecuritySupport;
/**
* Provides information about encodings. Depends on the Java runtime
* to provides writers for the different encodings, but can be used
* to override encoding names and provide the last printable character
* for each encoding.
*
* @version $Revision: 1.11 $ $Date: 2010-11-01 04:34:44 $
* @author <a href="mailto:arkin@intalio.com">Assaf Arkin
*/
public final class Encodings extends Object
{
/**
* The last printable character for unknown encodings.
*/
private static final int m_defaultLastPrintable = 0x7F;
/**
* Standard filename for properties file with encodings data.
*/
private static final String ENCODINGS_FILE = "com/sun/org/apache/xml/internal/serializer/Encodings.properties";
/**
* Standard filename for properties file with encodings data.
*/
private static final String ENCODINGS_PROP = "com.sun.org.apache.xalan.internal.serialize.encodings";
/**
* Returns a writer for the specified encoding based on
* an output stream.
*
* @param output The output stream
* @param encoding The encoding
* @return A suitable writer
* @throws UnsupportedEncodingException There is no convertor
* to support this encoding
*/
static Writer getWriter(OutputStream output, String encoding)
throws UnsupportedEncodingException
{
final EncodingInfo ei = _encodingInfos.findEncoding(toUpperCaseFast(encoding));
if (ei != null) {
try {
return new BufferedWriter(new OutputStreamWriter(
output, ei.javaName));
} catch (UnsupportedEncodingException usee) {
// keep trying
}
}
return new BufferedWriter(new OutputStreamWriter(output, encoding));
}
/**
* Returns the last printable character for an unspecified
* encoding.
*
* @return the default size
*/
public static int getLastPrintable()
{
return m_defaultLastPrintable;
}
/**
* Returns the EncodingInfo object for the specified
* encoding.
* <p>
* This is not a public API.
*
* @param encoding The encoding
* @return The object that is used to determine if
* characters are in the given encoding.
* @xsl.usage internal
*/
static EncodingInfo getEncodingInfo(String encoding)
{
EncodingInfo ei;
String normalizedEncoding = toUpperCaseFast(encoding);
ei = _encodingInfos.findEncoding(normalizedEncoding);
if (ei == null) {
// We shouldn't have to do this, but just in case.
try {
// This may happen if the caller tries to use
// an encoding that wasn't registered in the
// (java name)->(preferred mime name) mapping file.
// In that case we attempt to load the charset for the
// given encoding, and if that succeeds - we create a new
// EncodingInfo instance - assuming the canonical name
// of the charset can be used as the mime name.
final Charset c = Charset.forName(encoding);
final String name = c.name();
ei = new EncodingInfo(name, name);
_encodingInfos.putEncoding(normalizedEncoding, ei);
} catch (IllegalCharsetNameException | UnsupportedCharsetException x) {
ei = new EncodingInfo(null,null);
}
}
return ei;
}
/**
* A fast and cheap way to uppercase a String that is
* only made of printable ASCII characters.
* <p>
* This is not a public API.
* @param s a String of ASCII characters
* @return an uppercased version of the input String,
* possibly the same String.
* @xsl.usage internal
*/
static private String toUpperCaseFast(final String s) {
boolean different = false;
final int mx = s.length();
char[] chars = new char[mx];
for (int i=0; i < mx; i++) {
char ch = s.charAt(i);
// is the character a lower case ASCII one?
if ('a' <= ch && ch <= 'z') {
// a cheap and fast way to uppercase that is good enough
ch = (char) (ch + ('A' - 'a'));
different = true; // the uppercased String is different
}
chars[i] = ch;
}
// A little optimization, don't call String.valueOf() if
// the uppercased string is the same as the input string.
final String upper;
if (different)
upper = String.valueOf(chars);
else
upper = s;
return upper;
}
/** The default encoding, ISO style, ISO style. */
static final String DEFAULT_MIME_ENCODING = "UTF-8";
/**
* Get the proper mime encoding. From the XSLT recommendation: "The encoding
* attribute specifies the preferred encoding to use for outputting the result
* tree. XSLT processors are required to respect values of UTF-8 and UTF-16.
* For other values, if the XSLT processor does not support the specified
* encoding it may signal an error; if it does not signal an error it should
* use UTF-8 or UTF-16 instead. The XSLT processor must not use an encoding
* whose name does not match the EncName production of the XML Recommendation
* [XML]. If no encoding attribute is specified, then the XSLT processor should
* use either UTF-8 or UTF-16."
*
* @param encoding Reference to java-style encoding string, which may be null,
* in which case a default will be found.
*
* @return The ISO-style encoding string, or null if failure.
*/
static String getMimeEncoding(String encoding)
{
if (null == encoding)
{
try
{
// Get the default system character encoding. This may be
// incorrect if they passed in a writer, but right now there
// seems to be no way to get the encoding from a writer.
encoding = SecuritySupport.getSystemProperty("file.encoding", "UTF8");
if (null != encoding)
{
/*
* See if the mime type is equal to UTF8. If you don't
* do that, then convertJava2MimeEncoding will convert
* 8859_1 to "ISO-8859-1", which is not what we want,
* I think, and I don't think I want to alter the tables
* to convert everything to UTF-8.
*/
String jencoding =
(encoding.equalsIgnoreCase("Cp1252")
|| encoding.equalsIgnoreCase("ISO8859_1")
|| encoding.equalsIgnoreCase("8859_1")
|| encoding.equalsIgnoreCase("UTF8"))
? DEFAULT_MIME_ENCODING
: convertJava2MimeEncoding(encoding);
encoding =
(null != jencoding) ? jencoding : DEFAULT_MIME_ENCODING;
}
else
{
encoding = DEFAULT_MIME_ENCODING;
}
}
catch (SecurityException se)
{
encoding = DEFAULT_MIME_ENCODING;
}
}
else
{
encoding = convertJava2MimeEncoding(encoding);
}
return encoding;
}
/**
* Try the best we can to convert a Java encoding to a XML-style encoding.
*
* @param encoding non-null reference to encoding string, java style.
*
* @return ISO-style encoding string.
*/
private static String convertJava2MimeEncoding(String encoding)
{
final EncodingInfo enc =
_encodingInfos.getEncodingFromJavaKey(toUpperCaseFast(encoding));
if (null != enc)
return enc.name;
return encoding;
}
/**
* Try the best we can to convert a Java encoding to a XML-style encoding.
*
* @param encoding non-null reference to encoding string, java style.
*
* @return ISO-style encoding string.
*/
public static String convertMime2JavaEncoding(String encoding)
{
final EncodingInfo info = _encodingInfos.findEncoding(toUpperCaseFast(encoding));
return info != null ? info.javaName : encoding;
}
// Using an inner static class here prevent initialization races
// where the hash maps could be used before they were populated.
//
private final static class EncodingInfos {
// These maps are final and not modified after initialization.
private final Map<String, EncodingInfo> _encodingTableKeyJava = new HashMap<>();
private final Map<String, EncodingInfo> _encodingTableKeyMime = new HashMap<>();
// This map will be added to after initialization: make sure it's
// thread-safe. This map should not be used frequently - only in cases
// where the mapping requested was not declared in the Encodings.properties
// file.
private final Map<String, EncodingInfo> _encodingDynamicTable =
Collections.synchronizedMap(new HashMap<String, EncodingInfo>());
private EncodingInfos() {
loadEncodingInfo();
}
// Opens the file/resource containing java charset name -> preferred mime
// name mapping and returns it as an InputStream.
private InputStream openEncodingsFileStream() throws MalformedURLException, IOException {
String urlString = null;
InputStream is = null;
try {
urlString = SecuritySupport.getSystemProperty(ENCODINGS_PROP, "");
} catch (SecurityException e) {
}
if (urlString != null && urlString.length() > 0) {
URL url = new URL(urlString);
is = url.openStream();
}
if (is == null) {
is = SecuritySupport.getResourceAsStream(ENCODINGS_FILE);
}
return is;
}
// Loads the Properties resource containing the mapping:
// java charset name -> preferred mime name
// and returns it.
private Properties loadProperties() throws MalformedURLException, IOException {
Properties props = new Properties();
try (InputStream is = openEncodingsFileStream()) {
if (is != null) {
props.load(is);
} else {
// Seems to be no real need to force failure here, let the
// system do its best... The issue is not really very critical,
// and the output will be in any case _correct_ though maybe not
// always human-friendly... :)
// But maybe report/log the resource problem?
// Any standard ways to report/log errors (in static context)?
}
}
return props;
}
// Parses the mime list associated to a java charset name.
// The first mime name in the list is supposed to be the preferred
// mime name.
private String[] parseMimeTypes(String val) {
int pos = val.indexOf(' ');
//int lastPrintable;
if (pos < 0) {
// Maybe report/log this problem?
// "Last printable character not defined for encoding " +
// mimeName + " (" + val + ")" ...
return new String[] { val };
//lastPrintable = 0x00FF;
}
//lastPrintable =
// Integer.decode(val.substring(pos).trim()).intValue();
StringTokenizer st =
new StringTokenizer(val.substring(0, pos), ",");
String[] values = new String[st.countTokens()];
for (int i=0; st.hasMoreTokens(); i++) {
values[i] = st.nextToken();
}
return values;
}
// This method here attempts to find the canonical charset name for the
// the given name - which is supposed to be either a java name or a mime
// name.
// For that, it attempts to load the charset using the given name, and
// then returns the charset's canonical name.
// If the charset could not be loaded from the given name,
// the method returns null.
private String findCharsetNameFor(String name) {
try {
return Charset.forName(name).name();
} catch (Exception x) {
return null;
}
}
// This method here attempts to find the canonical charset name for the
// the set javaName+mimeNames - which are supposed to all refer to the
// same charset.
// For that it attempts to load the charset using the javaName, and if
// not found, attempts again using each of the mime names in turn.
// If the charset could be loaded from the javaName, then the javaName
// itself is returned as charset name. Otherwise, each of the mime names
// is tried in turn, until a charset can be loaded from one of the names,
// and the loaded charset's canonical name is returned.
// If no charset can be loaded from either the javaName or one of the
// mime names, then null is returned.
//
// Note that the returned name is the 'java' name that will be used in
// instances of EncodingInfo.
// This is important because EncodingInfo uses that 'java name' later on
// in calls to String.getBytes(javaName).
// As it happens, sometimes only one element of the set mime names/javaName
// is known by Charset: sometimes only one of the mime names is known,
// sometime only the javaName is known, sometimes all are known.
//
// By using this method here, we fix the problem where one of the mime
// names is known but the javaName is unknown, by associating the charset
// loaded from one of the mime names with the unrecognized javaName.
//
// When none of the mime names or javaName are known - there's not much we can
// do... It can mean that this encoding is not supported for this
// OS. If such a charset is ever use it will result in having all characters
// escaped.
//
private String findCharsetNameFor(String javaName, String[] mimes) {
String cs = findCharsetNameFor(javaName);
if (cs != null) return javaName;
for (String m : mimes) {
cs = findCharsetNameFor(m);
if (cs != null) break;
}
return cs;
}
/**
* Loads a list of all the supported encodings.
*
* System property "encodings" formatted using URL syntax may define an
* external encodings list. Thanks to Sergey Ushakov for the code
* contribution!
*/
private void loadEncodingInfo() {
try {
// load (java name)->(preferred mime name) mapping.
final Properties props = loadProperties();
// create instances of EncodingInfo from the loaded mapping
Enumeration keys = props.keys();
Map<String, EncodingInfo> canonicals = new HashMap<>();
while (keys.hasMoreElements()) {
final String javaName = (String) keys.nextElement();
final String[] mimes = parseMimeTypes(props.getProperty(javaName));
final String charsetName = findCharsetNameFor(javaName, mimes);
if (charsetName != null) {
final String kj = toUpperCaseFast(javaName);
final String kc = toUpperCaseFast(charsetName);
for (int i = 0; i < mimes.length; ++i) {
final String mimeName = mimes[i];
final String km = toUpperCaseFast(mimeName);
EncodingInfo info = new EncodingInfo(mimeName, charsetName);
_encodingTableKeyMime.put(km, info);
if (!canonicals.containsKey(kc)) {
// canonicals will map the charset name to
// the info containing the prefered mime name
// (the preferred mime name is the first mime
// name in the list).
canonicals.put(kc, info);
_encodingTableKeyJava.put(kc, info);
}
_encodingTableKeyJava.put(kj, info);
}
} else {
// None of the java or mime names on the line were
// recognized => this charset is not supported?
}
}
// Fix up the _encodingTableKeyJava so that the info mapped to
// the java name contains the preferred mime name.
// (a given java name can correspond to several mime name,
// but we want the _encodingTableKeyJava to point to the
// preferred mime name).
for (Entry<String, EncodingInfo> e : _encodingTableKeyJava.entrySet()) {
e.setValue(canonicals.get(toUpperCaseFast(e.getValue().javaName)));
}
} catch (java.net.MalformedURLException mue) {
throw new com.sun.org.apache.xml.internal.serializer.utils.WrappedRuntimeException(mue);
} catch (java.io.IOException ioe) {
throw new com.sun.org.apache.xml.internal.serializer.utils.WrappedRuntimeException(ioe);
}
}
EncodingInfo findEncoding(String normalizedEncoding) {
EncodingInfo info = _encodingTableKeyJava.get(normalizedEncoding);
if (info == null) {
info = _encodingTableKeyMime.get(normalizedEncoding);
}
if (info == null) {
info = _encodingDynamicTable.get(normalizedEncoding);
}
return info;
}
EncodingInfo getEncodingFromMimeKey(String normalizedMimeName) {
return _encodingTableKeyMime.get(normalizedMimeName);
}
EncodingInfo getEncodingFromJavaKey(String normalizedJavaName) {
return _encodingTableKeyJava.get(normalizedJavaName);
}
void putEncoding(String key, EncodingInfo info) {
_encodingDynamicTable.put(key, info);
}
}
/**
* Return true if the character is the high member of a surrogate pair.
* <p>
* This is not a public API.
* @param ch the character to test
* @xsl.usage internal
*/
static boolean isHighUTF16Surrogate(char ch) {
return ('\uD800' <= ch && ch <= '\uDBFF');
}
/**
* Return true if the character is the low member of a surrogate pair.
* <p>
* This is not a public API.
* @param ch the character to test
* @xsl.usage internal
*/
static boolean isLowUTF16Surrogate(char ch) {
return ('\uDC00' <= ch && ch <= '\uDFFF');
}
/**
* Return the unicode code point represented by the high/low surrogate pair.
* <p>
* This is not a public API.
* @param highSurrogate the high char of the high/low pair
* @param lowSurrogate the low char of the high/low pair
* @xsl.usage internal
*/
static int toCodePoint(char highSurrogate, char lowSurrogate) {
int codePoint =
((highSurrogate - 0xd800) << 10)
+ (lowSurrogate - 0xdc00)
+ 0x10000;
return codePoint;
}
/**
* Return the unicode code point represented by the char.
* A bit of a dummy method, since all it does is return the char,
* but as an int value.
* <p>
* This is not a public API.
* @param ch the char.
* @xsl.usage internal
*/
static int toCodePoint(char ch) {
int codePoint = ch;
return codePoint;
}
private final static EncodingInfos _encodingInfos = new EncodingInfos();
}
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