org.apache.jackrabbit.vault.util.xml.serialize.EncodingInfo Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
package org.apache.jackrabbit.vault.util.xml.serialize;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.IllegalCharsetNameException;
import java.nio.charset.UnsupportedCharsetException;
import org.apache.jackrabbit.vault.util.xml.xerces.util.EncodingMap;
/**
* This class represents an encoding.
*
* @version $Id$
*/
public class EncodingInfo {
// Method: sun.io.CharToByteConverter.getConverter(java.lang.String)
private static java.lang.reflect.Method fgGetConverterMethod = null;
// Method: sun.io.CharToByteConverter.canConvert(char)
private static java.lang.reflect.Method fgCanConvertMethod = null;
// Flag indicating whether or not sun.io.CharToByteConverter is available.
private static boolean fgConvertersAvailable = false;
// An array to hold the argument for a method of CharToByteConverter.
private Object[] fArgsForMethod = null;
// name of encoding as registered with IANA;
// preferably a MIME name, but aliases are fine too.
String ianaName;
String javaName;
int lastPrintable;
// The charToByteConverter with which we test unusual characters.
Object fCharToByteConverter = null;
// Is the converter null because it can't be instantiated
// for some reason (perhaps we're running with insufficient authority as
// an applet?
boolean fHaveTriedCToB = false;
Charset nioCharset = null;
CharsetEncoder nioCharEncoder = null;
/**
* Creates new {@code EncodingInfo} instance.
*/
public EncodingInfo(String ianaName, String javaName, int lastPrintable) {
this.ianaName = ianaName;
this.javaName = EncodingMap.getIANA2JavaMapping(ianaName);
this.lastPrintable = lastPrintable;
try {
nioCharset = Charset.forName(this.javaName);
if (nioCharset.canEncode())
nioCharEncoder = nioCharset.newEncoder();
} catch (IllegalCharsetNameException ie) {
nioCharset = null;
nioCharEncoder = null;
} catch (UnsupportedCharsetException ue) {
nioCharset = null;
nioCharEncoder = null;
}
}
/**
* Returns a MIME charset name of this encoding.
*/
public String getIANAName() {
return this.ianaName;
}
/**
* Returns a writer for this encoding based on
* an output stream.
*
* @return A suitable writer
* @throws UnsupportedEncodingException There is no convertor
* to support this encoding
*/
public Writer getWriter(OutputStream output)
throws UnsupportedEncodingException {
// this should always be true!
if (javaName != null)
return new OutputStreamWriter(output, javaName);
javaName = EncodingMap.getIANA2JavaMapping(ianaName);
if (javaName == null)
// use UTF-8 as preferred encoding
return new OutputStreamWriter(output, "UTF8");
return new OutputStreamWriter(output, javaName);
}
/**
* Checks whether the specified character is printable or not
* in this encoding.
*
* @param ch a code point (0-0x10ffff)
*/
public boolean isPrintable(char ch) {
if (ch <= this.lastPrintable)
return true;
if (nioCharEncoder != null)
return nioCharEncoder.canEncode(ch);
//We should not reach here , if we reach due to
//charset not supporting encoding then fgConvertersAvailable
//should take care of returning false.
if (fCharToByteConverter == null) {
if (fHaveTriedCToB || !fgConvertersAvailable) {
// forget it; nothing we can do...
return false;
}
if (fArgsForMethod == null) {
fArgsForMethod = new Object[1];
}
// try and create it:
try {
fArgsForMethod[0] = javaName;
fCharToByteConverter = fgGetConverterMethod.invoke(null, fArgsForMethod);
} catch (Exception e) {
// don't try it again...
fHaveTriedCToB = true;
return false;
}
}
try {
fArgsForMethod[0] = new Character(ch);
return ((Boolean) fgCanConvertMethod.invoke(fCharToByteConverter, fArgsForMethod)).booleanValue();
} catch (Exception e) {
// obviously can't use this converter; probably some kind of
// security restriction
fCharToByteConverter = null;
fHaveTriedCToB = false;
return false;
}
}
// is this an encoding name recognized by this JDK?
// if not, will throw UnsupportedEncodingException
public static void testJavaEncodingName(String name) throws UnsupportedEncodingException {
final byte[] bTest = {(byte) 'v', (byte) 'a', (byte) 'l', (byte) 'i', (byte) 'd'};
String s = new String(bTest, name);
}
// Attempt to get methods for char to byte
// converter on class initialization.
static {
try {
Class clazz = Class.forName("sun.io.CharToByteConverter");
fgGetConverterMethod = clazz.getMethod("getConverter", new Class[]{String.class});
fgCanConvertMethod = clazz.getMethod("canConvert", new Class[]{Character.TYPE});
fgConvertersAvailable = true;
}
// ClassNotFoundException, NoSuchMethodException or SecurityException
// Whatever the case, we cannot use sun.io.CharToByteConverter.
catch (Exception exc) {
fgGetConverterMethod = null;
fgCanConvertMethod = null;
fgConvertersAvailable = false;
}
}
}