QXmlStreamReader Class

QXmlStreamReader provides a simple streaming API to parse well-formed XML. It is an alternative to first loading the complete XML into a DOM tree (see QDomDocument). QXmlStreamReader reads data either from a QIODevice (see setDevice()), or from a raw QByteArray (see addData()).

Qt provides QXmlStreamWriter for writing XML.

The basic concept of a stream reader is to report an XML document as a stream of tokens, similar to SAX. The main difference between QXmlStreamReader and SAX is how these XML tokens are reported. With SAX, the application must provide handlers (callback functions) that receive so-called XML events from the parser at the parser's convenience. With QXmlStreamReader, the application code itself drives the loop and pulls tokens from the reader, one after another, as it needs them. This is done by calling readNext(), where the reader reads from the input stream until it completes the next token, at which point it returns the tokenType(). A set of convenient functions including isStartElement() and text() can then be used to examine the token to obtain information about what has been read. The big advantage of this pulling approach is the possibility to build recursive descent parsers with it, meaning you can split your XML parsing code easily into different methods or classes. This makes it easy to keep track of the application's own state when parsing XML.

A typical loop with QXmlStreamReader looks like this:

  QXmlStreamReader xml;
  ...
  while (!xml.atEnd()) {
        xml.readNext();
        ... // do processing
  }
  if (xml.hasError()) {
        ... // do error handling
  }

QXmlStreamReader is a well-formed XML 1.0 parser that does not include external parsed entities. As long