I have to read and xml file, do some changes, and copy it to another location. I also have to keep the german special characters, and keep the empty tags as they are (prevent them to become self-closing tags). For preventing the self closing tags, I used Xerces Library, as in the link:
preventing empty xml elements are converted to self closing elements
In my application, if my changes in xml are ignored, the code looks like:
public static void main(String args[]) throws Exception {
InputStream inputStream= new FileInputStream(new File("D:\\qwe.xml"));
Reader reader = new InputStreamReader(inputStream,"ISO-8859-1");
InputSource is = new InputSource(reader);
is.setEncoding("ISO-8859-1");
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder;
dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(is);
doc.setXmlStandalone(true);
File file = new File ("D:\\qwerty.xml");
XMLStreamWriter writer = XMLOutputFactory.newFactory().createXMLStreamWriter(new FileOutputStream(file));
Transformer transformer = TransformerFactory.newInstance().newTransformer();
transformer.setOutputProperty(OutputKeys.ENCODING, "ISO-8859-1") ;
transformer.transform(new DOMSource(doc), new StAXResult(writer));
}
The first row in the source file is
<?xml version="1.0" encoding="UTF-8"?>
The problem is in the destination file, qwerty.xml, where encoding="UTF-8" is removed. In the source file, although the encoding is UTF-8, I had to set it as "ISO-8859-1" because of german characters. I want to keep the first row as the original, keep the empty tags as they are (not self-closing tags), and keep the german characters. My code succeeds to do only the second and third thing.
The call
Transformer.setOutputProperty(OutputKeys.ENCODING, "ISO-8859-1");
has no effect unless the transformer is producing serialized output.
In your case the transformer is not producing serialized output because you are sending the output to a StAXResult. I'm not sure why you are using the XmlStreamWriter to produce output, but if you want to do it that way, it's the XmlStreamWriter that decides on the encoding, not the Transformer.
I would have thought it was simpler to send the Transformer output to a StreamResult.
Related
I have a xml file as object in Java as org.w3c.dom.Document doc and I want to convert this into File file. How can I convert the type Document to File?
thanks
I want to add metadata elements in an existing xml file (standard dita) with type File.
I know a way to add elements to the file, but then I have to convert the file to a org.w3c.dom.Document. I did that with the method loadXML:
private Document loadXML(File f) throws Exception{
DocumentBuilder b = DocumentBuilderFactory.newInstance().newDocumentBuilder();
return builder.parse(f);
After that I change the org.w3c.dom.Document, then I want to continue with the flow of the program and I have to convert the Document doc back to a File file.
What is a efficient way to do that? Or what is a better solution to get some elements in a xml File without converting it?
You can use a Transformer class to output the entire XML content to a File, as showed below:
Document doc =...
// write the content into xml file
DOMSource source = new DOMSource(doc);
FileWriter writer = new FileWriter(new File("/tmp/output.xml"));
StreamResult result = new StreamResult(writer);
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
transformer.transform(source, result);
With JDK 1.8.0 a short way is to use the built-in XMLSerializer (which was introduced with JDK 1.4 as a fork of Apache Xerces)
import com.sun.org.apache.xml.internal.serialize.XMLSerializer;
Document doc = //use your method loadXML(File f)
//change Document
java.io.Writer writer = new java.io.FileWriter("MyOutput.xml");
XMLSerializer xml = new XMLSerializer(writer, null);
xml.serialize(doc);
Use an object of type OutputFormat to configure output, for example like this:
OutputFormat format = new OutputFormat(Method.XML, StandardCharsets.UTF_8.toString(), true);
format.setIndent(4);
format.setLineWidth(80);
format.setPreserveEmptyAttributes(true);
format.setPreserveSpace(true);
XMLSerializer xml = new XMLSerializer(writer, format);
Note that the classes are from com.sun.* package which is not documented and therefore generally is not seen as the preferred way of doing things. However, with javax.xml.transform.OutputKeys you cannot specify the amount of indentation or line width for example. So, if this is important then this solution should help.
My code receives an XML String from an InputStreamReader (it's actually the output of REST request to another server) and then the String is written to a file (file includes not only XML).
The problem is that the String is received as one line of XML and so it's stored as one huge line in the file (no indentation, tabs, formatting etc.).
Can I receive this XML stream and format it while writing it to the file?
Note: I can't use DOM here, it must be implemented without loading the XML to memory.
You can do it using Transformer and SAX, if you are allowed to :-
public static void prettyPrintXmlToFile(String sourceXml, File targetFile) throws Exception{
Transformer serializer = SAXTransformerFactory.newInstance().newTransformer();
serializer.setOutputProperty(OutputKeys.INDENT, "yes");
serializer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
Source xmlSource = new SAXSource(new InputSource(new StringReader(sourceXml)));
StreamResult res = new StreamResult(targetFile);
serializer.transform(xmlSource, res);
}
I convert org.w3c.dom.Element to String in this way:
StringWriter writer = new StringWriter();
Transformer transformer = TransformerFactory.newInstance().newTransformer();
transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
transformer.transform(new DOMSource(node), new StreamResult(writer));
String result = writer.toString();
But when I use it later I get an exception: io.MalformedByteSequenceException: Invalid byte 1 of 1-byte UTF-8 sequence which says about wrong encoding.
In fact, it's completely unnecessery. I needed it for serialization nodes and further export them to different formats (xml, html, test). So I found out that it's better to share org.w3c.dom Documents. From Document you can get any information you need.
I get a SOAP message from a web service, and I can convert the response string to an XML file using the below code. This works fine. But my requirement is not to write the SOAP message to a file. I just need to keep this XML document object in memory, and extract some elements to be used in further processing. However, if I just try to access the document object below, it comes as empty.
Can somebody please tell me how I can convert a String to an in-memory XML object (without having to write to a file)?
String xmlString = new String(data);
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder;
try
{
builder = factory.newDocumentBuilder();
// Use String reader
Document document = builder.parse( new InputSource(
new StringReader( xmlString ) ) );
TransformerFactory tranFactory = TransformerFactory.newInstance();
Transformer aTransformer = tranFactory.newTransformer();
Source src = new DOMSource( document );
Result dest = new StreamResult( new File( "xmlFileName.xml" ) );
aTransformer.transform( src, dest );
}
Remove the 5 last lines of code, and you'll just have the DOM document in memory. Store this document in some field, rather than in a local variable.
If that isn't sufficient, then please explain, with code, what you mean with "if I just try to access the document object below, it comes as empty".
JB Nizet is right, the first steps create a DOM out of xmlString. That will load your xmlString (or SOAP message) into an in-memory Document. What the following steps are doing (all the things related with the Transform) is to serialize the DOM to a file (xmlFileName.xml), which is not what you want to do, right?
When you said that your DOM is empty, I think you tried to print out the content of your DOM with document.toString(), and returned something like "[document: null]". This doesn't mean your DOM is empty. Actually your DOM contains data. You need now to use the DOM API to get access to the nodes inside your document. Try something like document.getChildNodes(), document.getElementsByTagName(), etc
How do I control the order that the XML attributes are listed within the output file?
It seems by default they are getting alphabetized, which the program I'm sending this XML to apparently isn't handling.
e.g. I want zzzz to show first, then bbbbb in the following code.
DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
Document doc = docBuilder.newDocument();
Element root = doc.createElement("requests");
doc.appendChild(root);
root.appendChild(request);
root.setAttribute("zzzzzz", "My z value");
root.setAttribute("bbbbbbb", "My b value");
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(new File(file));
transformer.transform(source, result);
The order of attributes is defined to be insignificant in XML: no conformant XML application should produce results that depend on the order in which attributes appear. Therefore, serializers (code that produces lexical XML as output) will usually give you no control over the order.
Now, it would sometimes be nice to have that control for cosmetic reasons, because XML is designed to be human-readable. So there's a valid reason for wanting the feature. But the fact is, I know of no serializer that offers it.
I had the same issue when I used XML DOM API for writing file. To resolve the problem I had to use XMLStreamWriter. Attributes appear in a xml file in the order you write it using XMLStreamWriter.
XML Canonicalisation results in a consistent attribute ordering, primarily to allow one to check a signature over some or all of the XML, though there are other potential uses. This may suit your purposes.
If you don't want to use another framework just for a custom attribute order you can simply add an order identifier to the attributes.
<someElement a__price="32" b__amount="3"/>
After the XML serializer is done post process the raw XML like so:
public static String removeAttributeOrderIdentifiers(String xml) {
return xml.replaceAll(
" [a-z]__(.+?=\")",
"$1"
);
}
And you will get:
<someElement amount="3" price="32"/>