JAXB将JAVA对象转换为XML时CDATA的问题

缺乏、安全感 2022-06-17 13:27 515阅读 0赞

对Java对象转换为xml字符串时，如果有特殊字符如<>必须要是用<!\[CDATA\[\]\]>来声明。我先尝试了使用XStream解决这个问题也有使用MOXy CDATA注解解决，最后发现，都存在一定的缺陷，甚至不能正常的实现该功能。

最终解决方案有两个，都可以解决这个问题，但是第一个方案由于引用了sun的专有API，在编译时会存在警告，使用了内部的API并不是值得推荐的。但是这里也贴出来，供大家参考。

sunAPI版：

首先继承XMLSerializer

import com.sun.org.apache.xml.internal.serialize.OutputFormat;
    import com.sun.org.apache.xml.internal.serialize.XMLSerializer;
    import org.xml.sax.SAXException;
    
    import java.io.OutputStream;
    import java.util.regex.Pattern;
    
    public class CDataContentHandler extends XMLSerializer {
        private static final Pattern XML_CHARS = Pattern.compile("[<>&]");
    
        public CDataContentHandler( OutputStream output, OutputFormat format ) {
           super(output,format);
        }
    
        public void characters(char[] ch, int start, int length) throws SAXException {
            boolean useCData = XML_CHARS.matcher(new String(ch, start, length)).find();
            if (useCData) super.startCDATA();
            super.characters(ch, start, length);
            if (useCData) super.endCDATA();
        }
    
    }

实际的转换方法：

public static String ojbectToXmlWithCDATA(Class clazz, Object obj) throws Exception {
    
    			JAXBContext context = JAXBContext.newInstance(clazz);
    
    			OutputFormat of = new OutputFormat();
    			of.setOmitXMLDeclaration(true);
    			of.setPreserveSpace(true);
    			of.setIndenting(true);
    
    			ByteArrayOutputStream op = new ByteArrayOutputStream();
    			CDataContentHandler serializer = new CDataContentHandler(op, of);
    			SAXResult result = new SAXResult(serializer.asContentHandler());
    
    			Marshaller mar = context.createMarshaller();
    			mar.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
    			mar.marshal(obj, result);
    
    			return op.toString("UTF-8");
    		}

第二个方法是目前使用的方法，参考了一个国外同行的解决方法，这个解决方案将自定实现javax.xml.stream.xmlstreamwriter，没有第三方的库依赖：

执行类决定哪些地方需要添加CDATA：

import javax.xml.stream.XMLStreamException;
    import javax.xml.stream.XMLStreamWriter;
    import java.util.regex.Pattern;
     
    /**
     * Implementation which is able to decide to use a CDATA section for a string.
     */
    public class CDataXMLStreamWriter extends DelegatingXMLStreamWriter
    {
       private static final Pattern XML_CHARS = Pattern.compile( "[&<>]" );
     
       public CDataXMLStreamWriter( XMLStreamWriter del )
       {
          super( del );
       }
     
       @Override
       public void writeCharacters( String text ) throws XMLStreamException
       {
          boolean useCData = XML_CHARS.matcher( text ).find();
          if( useCData )
          {
             super.writeCData( text );
          }
          else
          {
             super.writeCharacters( text );
          }
       }
    }

委托类：

import javax.xml.namespace.NamespaceContext;
    import javax.xml.stream.XMLStreamException;
    import javax.xml.stream.XMLStreamWriter;
     
    /**
     * Delegating {@link XMLStreamWriter}.
     */
    abstract class DelegatingXMLStreamWriter implements XMLStreamWriter
    {
       private final XMLStreamWriter writer;
     
       public DelegatingXMLStreamWriter( XMLStreamWriter writer )
       {
          this.writer = writer;
       }
     
       public void writeStartElement( String localName ) throws XMLStreamException
       {
          writer.writeStartElement( localName );
       }
     
       public void writeStartElement( String namespaceURI, String localName ) throws XMLStreamException
       {
          writer.writeStartElement( namespaceURI, localName );
       }
     
       public void writeStartElement( String prefix, String localName, String namespaceURI ) throws XMLStreamException
       {
          writer.writeStartElement( prefix, localName, namespaceURI );
       }
     
       public void writeEmptyElement( String namespaceURI, String localName ) throws XMLStreamException
       {
          writer.writeEmptyElement( namespaceURI, localName );
       }
     
       public void writeEmptyElement( String prefix, String localName, String namespaceURI ) throws XMLStreamException
       {
          writer.writeEmptyElement( prefix, localName, namespaceURI );
       }
     
       public void writeEmptyElement( String localName ) throws XMLStreamException
       {
          writer.writeEmptyElement( localName );
       }
     
       public void writeEndElement() throws XMLStreamException
       {
          writer.writeEndElement();
       }
     
       public void writeEndDocument() throws XMLStreamException
       {
          writer.writeEndDocument();
       }
     
       public void close() throws XMLStreamException
       {
          writer.close();
       }
     
       public void flush() throws XMLStreamException
       {
          writer.flush();
       }
     
       public void writeAttribute( String localName, String value ) throws XMLStreamException
       {
          writer.writeAttribute( localName, value );
       }
     
       public void writeAttribute( String prefix, String namespaceURI, String localName, String value )
          throws XMLStreamException
       {
          writer.writeAttribute( prefix, namespaceURI, localName, value );
       }
     
       public void writeAttribute( String namespaceURI, String localName, String value ) throws XMLStreamException
       {
          writer.writeAttribute( namespaceURI, localName, value );
       }
     
       public void writeNamespace( String prefix, String namespaceURI ) throws XMLStreamException
       {
          writer.writeNamespace( prefix, namespaceURI );
       }
     
       public void writeDefaultNamespace( String namespaceURI ) throws XMLStreamException
       {
          writer.writeDefaultNamespace( namespaceURI );
       }
     
       public void writeComment( String data ) throws XMLStreamException
       {
          writer.writeComment( data );
       }
     
       public void writeProcessingInstruction( String target ) throws XMLStreamException
       {
          writer.writeProcessingInstruction( target );
       }
     
       public void writeProcessingInstruction( String target, String data ) throws XMLStreamException
       {
          writer.writeProcessingInstruction( target, data );
       }
     
       public void writeCData( String data ) throws XMLStreamException
       {
          writer.writeCData( data );
       }
     
       public void writeDTD( String dtd ) throws XMLStreamException
       {
          writer.writeDTD( dtd );
       }
     
       public void writeEntityRef( String name ) throws XMLStreamException
       {
          writer.writeEntityRef( name );
       }
     
       public void writeStartDocument() throws XMLStreamException
       {
          writer.writeStartDocument();
       }
     
       public void writeStartDocument( String version ) throws XMLStreamException
       {
          writer.writeStartDocument( version );
       }
     
       public void writeStartDocument( String encoding, String version ) throws XMLStreamException
       {
          writer.writeStartDocument( encoding, version );
       }
     
       public void writeCharacters( String text ) throws XMLStreamException
       {
          writer.writeCharacters( text );
       }
     
       public void writeCharacters( char[] text, int start, int len ) throws XMLStreamException
       {
          writer.writeCharacters( text, start, len );
       }
     
       public String getPrefix( String uri ) throws XMLStreamException
       {
          return writer.getPrefix( uri );
       }
     
       public void setPrefix( String prefix, String uri ) throws XMLStreamException
       {
          writer.setPrefix( prefix, uri );
       }
     
       public void setDefaultNamespace( String uri ) throws XMLStreamException
       {
          writer.setDefaultNamespace( uri );
       }
     
       public void setNamespaceContext( NamespaceContext context ) throws XMLStreamException
       {
          writer.setNamespaceContext( context );
       }
     
       public NamespaceContext getNamespaceContext()
       {
          return writer.getNamespaceContext();
       }
     
       public Object getProperty( String name ) throws IllegalArgumentException
       {
          return writer.getProperty( name );
       }
    }

示例方法：

/**使用JAXB方式解决CDATA问题
         *
         * @throws Exception
         */
        public static String ojbectToXmlWithCDATA(Class clazz, Object obj) throws Exception {
    
            JAXBContext context = JAXBContext.newInstance(clazz);
            ByteArrayOutputStream op = new ByteArrayOutputStream();
    
            XMLOutputFactory xof = XMLOutputFactory.newInstance();
            XMLStreamWriter streamWriter = xof.createXMLStreamWriter(op);
            CDataXMLStreamWriter cdataStreamWriter = new CDataXMLStreamWriter(streamWriter);
    
            Marshaller mar = context.createMarshaller();
            mar.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
            mar.marshal(obj, cdataStreamWriter);
          cdataStreamWriter.flush();
          cdataStreamWriter.close();
            return op.toString("UTF-8");
        }

生成后的xml代码示例：

<?xml version='1.0' encoding='utf-8'?>
    <businessMessages xmlns="http://aaa.xxx.com/schema/BusinessMessages">
        <businessMessage>
            <uuid>abcccc</uuid>
            <source>tms</source>
            <topic>type</topic>
            <bussinessNo>123</bussinessNo>
            <header></header>
            <body>
                <![CDATA[<pivotFlow xmlns="http://aaa.xxx.com/schema/PivotFlow"><orderId>112345</orderId><operPersonId>testOper</operPersonId><operTime>2016-02-16T16:13:40.364+08:00</operTime><status>testType</status><appendix>{"shipper":"testShip","carrierPhone":"1860132223","carrier":"testCarr"}</appendix></pivotFlow>]]>
    </body>
        </businessMessage>
    </businessMessages>

英文原文参考：[http://blog.mi-ernst.de/2012/05/04/jaxb-and-cdata-sections/][http_blog.mi-ernst.de_2012_05_04_jaxb-and-cdata-sections]

博客来源：[http://blog.csdn.net/wantken/article/details/50675549][http_blog.csdn.net_wantken_article_details_50675549]

[http_blog.mi-ernst.de_2012_05_04_jaxb-and-cdata-sections]: http://blog.mi-ernst.de/2012/05/04/jaxb-and-cdata-sections/
[http_blog.csdn.net_wantken_article_details_50675549]: http://blog.csdn.net/wantken/article/details/50675549