Java XMLStreamWriter: output di caratteri estesi Unicode (non BMP)

Question

Qualcuno sa come eseguire correttamente l'output di caratteri estesi (non BMP, più di 1 char) utilizzando XMLStreamWriter di Java? Ad esempio, cercando di uscita Unicode U + 10480 :

import java.io.OutputStreamWriter; 
import java.nio.charset.StandardCharsets; 

import javax.xml.stream.XMLOutputFactory; 
import javax.xml.stream.XMLStreamException; 
import javax.xml.stream.XMLStreamWriter; 

public class XmlStreamWriterExtendedCharactersFail { 
    public static void main(String[] args) throws XMLStreamException { 
     String inlineStr = "inlineStr = "; 
     // create string using StringBuilder to avoid Java file encoding confusion: 
     String sbStr = new StringBuilder("sbStr = ").appendCodePoint(0x10480).toString(); 
     assert sbStr.equals(inlineStr); 
     System.out.println(sbStr); 

     OutputStreamWriter outWriter = new OutputStreamWriter(System.out, 
       StandardCharsets.UTF_8.newEncoder()); 
     XMLStreamWriter writer = XMLOutputFactory.newFactory() 
       .createXMLStreamWriter(outWriter); 
     writer.writeStartDocument("UTF-8", "1.1"); 
     writer.writeStartElement("el"); 
     writer.writeCharacters(sbStr); 
     writer.writeEndElement(); 
     writer.writeEndDocument(); 
     writer.close(); 
    } 
} 

risultati in:

sbStr = 
<?xml version="1.1" encoding="UTF-8"?><el>sbStr = &#xd801;&#xdc80;</el> 

noti che �� sono punti codice non validi e porterà a un errore durante l'analisi con SAX.

risultato atteso:

sbStr = 
<?xml version="1.1" encoding="UTF-8"?><el>sbStr = </el> 

sbStr = ⣰ sarebbe anche fare in un pizzico, ma la prima è preferibile.

Answer 1

Si noti che Apache Commons 'StringEscapeUtils.escapeXML ha anche questo problema prima della versione 3.0.

Ho creato il seguente wrapper attorno a XMLStreamWriter come soluzione al mio problema. Sfugge ai dati dei personaggi usando Apache Commons e li scrive direttamente sul sottostante Writer.

import java.io.IOException; 
import java.io.Writer; 
import java.nio.CharBuffer; 

import javax.xml.namespace.NamespaceContext; 
import javax.xml.stream.FactoryConfigurationError; 
import javax.xml.stream.XMLOutputFactory; 
import javax.xml.stream.XMLStreamException; 
import javax.xml.stream.XMLStreamWriter; 

import org.apache.commons.lang3.StringEscapeUtils; 
import org.apache.commons.lang3.text.translate.CharSequenceTranslator; 

public class UnicodeXMLStreamWriter implements XMLStreamWriter { 
    private XMLStreamWriter xmlSW; 
    private Writer writer; 
    private CharSequenceTranslator characterEscapor = StringEscapeUtils.ESCAPE_XML11; 

    public static UnicodeXMLStreamWriter newInstance(Writer writer) throws XMLStreamException, FactoryConfigurationError { 
     return newInstance(writer, XMLOutputFactory.newFactory()); 
    } 

    public static UnicodeXMLStreamWriter newInstance(Writer writer, XMLOutputFactory factory) throws XMLStreamException { 
     XMLStreamWriter xmlSW = factory.createXMLStreamWriter(writer); 
     return new UnicodeXMLStreamWriter(writer, xmlSW); 
    } 

    public UnicodeXMLStreamWriter(Writer writer, XMLStreamWriter xmlSW) { 
     this.writer = writer; 
     this.xmlSW = xmlSW; 
    } 

    public void writeCharacters(String text) throws XMLStreamException { 
     // finish writing start element 
     xmlSW.writeCharacters(""); 
     xmlSW.flush(); 
     try { 
      characterEscapor.translate(text, writer); 
     } catch (IOException e) { 
      throw new XMLStreamException(e); 
     } 
    } 

    public void writeCharacters(char[] text, int start, int len) 
      throws XMLStreamException { 
     // finish writing start element 
     xmlSW.writeCharacters(""); 
     xmlSW.flush(); 
     try { 
      characterEscapor.translate(CharBuffer.wrap(text, start, len), writer); 
     } catch (IOException e) { 
      throw new XMLStreamException(e); 
     } 
    } 

    //////////////// REMAINING METHODS ARE DELEGATES to xmlSW //////////////// 

    public void writeStartElement(String localName) throws XMLStreamException { 
     xmlSW.writeStartElement(localName); 
    } 

    public void writeStartElement(String namespaceURI, String localName) 
      throws XMLStreamException { 
     xmlSW.writeStartElement(namespaceURI, localName); 
    } 

    public void writeStartElement(String prefix, String localName, 
      String namespaceURI) throws XMLStreamException { 
     xmlSW.writeStartElement(prefix, localName, namespaceURI); 
    } 

    public void writeEmptyElement(String namespaceURI, String localName) 
      throws XMLStreamException { 
     xmlSW.writeEmptyElement(namespaceURI, localName); 
    } 

    public void writeEmptyElement(String prefix, String localName, 
      String namespaceURI) throws XMLStreamException { 
     xmlSW.writeEmptyElement(prefix, localName, namespaceURI); 
    } 

    public void writeEmptyElement(String localName) throws XMLStreamException { 
     xmlSW.writeEmptyElement(localName); 
    } 

    public void writeEndElement() throws XMLStreamException { 
     xmlSW.writeEndElement(); 
    } 

    public void writeEndDocument() throws XMLStreamException { 
     xmlSW.writeEndDocument(); 
    } 

    public void close() throws XMLStreamException { 
     xmlSW.close(); 
    } 

    public void flush() throws XMLStreamException { 
     xmlSW.flush(); 
    } 

    public void writeAttribute(String localName, String value) 
      throws XMLStreamException { 
     xmlSW.writeAttribute(localName, value); 
    } 

    public void writeAttribute(String prefix, String namespaceURI, 
      String localName, String value) throws XMLStreamException { 
     xmlSW.writeAttribute(prefix, namespaceURI, localName, value); 
    } 

    public void writeAttribute(String namespaceURI, String localName, 
      String value) throws XMLStreamException { 
     xmlSW.writeAttribute(namespaceURI, localName, value); 
    } 

    public void writeNamespace(String prefix, String namespaceURI) 
      throws XMLStreamException { 
     xmlSW.writeNamespace(prefix, namespaceURI); 
    } 

    public void writeDefaultNamespace(String namespaceURI) 
      throws XMLStreamException { 
     xmlSW.writeDefaultNamespace(namespaceURI); 
    } 

    public void writeComment(String data) throws XMLStreamException { 
     xmlSW.writeComment(data); 
    } 

    public void writeProcessingInstruction(String target) 
      throws XMLStreamException { 
     xmlSW.writeProcessingInstruction(target); 
    } 

    public void writeProcessingInstruction(String target, String data) 
      throws XMLStreamException { 
     xmlSW.writeProcessingInstruction(target, data); 
    } 

    public void writeCData(String data) throws XMLStreamException { 
     xmlSW.writeCData(data); 
    } 

    public void writeDTD(String dtd) throws XMLStreamException { 
     xmlSW.writeDTD(dtd); 
    } 

    public void writeEntityRef(String name) throws XMLStreamException { 
     xmlSW.writeEntityRef(name); 
    } 

    public void writeStartDocument() throws XMLStreamException { 
     xmlSW.writeStartDocument(); 
    } 

    public void writeStartDocument(String version) throws XMLStreamException { 
     xmlSW.writeStartDocument(version); 
    } 

    public void writeStartDocument(String encoding, String version) 
      throws XMLStreamException { 
     xmlSW.writeStartDocument(encoding, version); 
    } 

    public String getPrefix(String uri) throws XMLStreamException { 
     return xmlSW.getPrefix(uri); 
    } 

    public void setPrefix(String prefix, String uri) throws XMLStreamException { 
     xmlSW.setPrefix(prefix, uri); 
    } 

    public void setDefaultNamespace(String uri) throws XMLStreamException { 
     xmlSW.setDefaultNamespace(uri); 
    } 

    public void setNamespaceContext(NamespaceContext context) 
      throws XMLStreamException { 
     xmlSW.setNamespaceContext(context); 
    } 

    public NamespaceContext getNamespaceContext() { 
     return xmlSW.getNamespaceContext(); 
    } 

    public Object getProperty(String name) throws IllegalArgumentException { 
     return xmlSW.getProperty(name); 
    } 
} 

Utilizzando questo risultato nell'output desiderato. Ora per presentare un bug report ...