使用OutputStreamWriter（StAX解析器）将数据附加到XML文件

Question

I want to append data to an XML file using OutputStreamWriter but ending up something like below

<?xml version="1.0" encoding="utf-8"?>
<doc>
 <msg>
   <tag1>data1</tag1>
   ...
 </msg>
</doc>
<?xml version="1.0" encoding="utf-8"?>
<doc>
 <msg>
   <tag1>data2</tag1>
   ...
 </msg>
</doc>

How can I achieve the correct format

<?xml version="1.0" encoding="utf-8"?>
<doc>
 <msg>
   <tag1>data1</tag1>
   ...
 </msg>
 <msg>
   <tag1>data2</tag1>
   ...
 </msg>
</doc>

I have tried with below code

 XMLOutputFactory outputFactory = XMLOutputFactory.newInstance();
    File file = new File(outputFile);
    Writer fw = null;
    XMLStreamWriter w = null;

    try {
        if(!file.isFile()) {
            file.createNewFile();
        }
        fw = new OutputStreamWriter(new FileOutputStream(file, true), "UTF-8"); 
        w = outputFactory.createXMLStreamWriter(fw);
        w.writeStartDocument("utf-8", "1.0");
        w.writeStartElement("doc");

        createMessageElement(fingerPrint, w, data);//method to write data

        w.writeEndElement();
        w.writeEndDocument();

        w.flush();
        w.close();

        w.close();

        fw.flush();
        fw.close();

Please give me suggestion. I'm new to StAX.

Answer 1

Your example is only appending a new xml document to the end of a file. If you want to append data to an existing xml doc you have to read the source xml, and write it to another file, inserting your new element as need.... see http://docs.oracle.com/javase/tutorial/jaxp/stax/example.html#bnbgq for an example using stax api.

Answer 2

Use below code you get the output.

XMLOutputFactory factory = XMLOutputFactory.newInstance();

    try {

        XMLStreamWriter writer1 = factory.createXMLStreamWriter(new FileWriter("E:\\sampleXML.xml"));

        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        XMLStreamWriter2 xtw = (XMLStreamWriter2) new WstxOutputFactory()
                .createXMLStreamWriter(byteArrayOutputStream, "UTF-8");

        xtw.writeStartDocument("UTF-8", "1.1");

        xtw.writeStartElement("doc");

        XMLStreamWriter2 writer2 = createMessageElement(xtw);

        writer2.writeStartElement("msg");
        writer2.writeStartElement("tag1");
        writer2.writeCharacters("data1");
        writer2.writeEndElement();
        writer2.writeStartElement("tag2");
        writer2.writeCharacters("data2");
        writer2.writeEndElement();


        writer2.writeEndDocument();
        writer2.close();
        xtw.flush();
        xtw.close();

        System.out.println("XML :" + new String(byteArrayOutputStream.toByteArray()));

    } catch (XMLStreamException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

private static XMLStreamWriter2 createMessageElement(XMLStreamWriter2 writer2)
        throws XMLStreamException, IOException {
        try {
        writer2.writeStartElement("msg");
        writer2.writeStartElement("tag1");
        writer2.writeCharacters("data1");
        writer2.writeEndElement();
        writer2.writeStartElement("tag2");
        writer2.writeCharacters("data2");
        writer2.writeEndElement();

        writer2.writeEndElement();

        writer2.flush();
    } catch (Exception e) {
        e.printStackTrace();
    }
    return writer2;

}