Java XML解析器？

Question

I'm currently converting a program I wrote in Visual Basic .NET (the 2005 variety) into Java. It used built-in XML methods to parse and generate the user's saved data, does Java have an equivalent feature built in or am I going to have to change file processing implementations? (I'd rather not, there's a lot of code I'd have to change.)

Answer 1

Yes, Java can parse XML. Here's an example that takes in a String that contains XML and builds a Document object out of it:

DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
InputSource inputSource = new InputSource(new StringReader(xml));
Document document = documentBuilder.parse(inputSource);

You can then use the XPath API to query the dom. Here's a tutorial/writeup about it.

As far as serializing objects to XML, the official implementation is JAXB and it is part of Java since 1.6. Here's a simple example. It will let you serialize and deserialize to and from XML.

You can also create a DOM object manually and add nodes to it, but it's a little more tedious:

DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
Document document = documentBuilder.newDocument();

Element rootNode = document.createElement("root");

Element childNode = document.createElement("child");
childNode.setTextContent("I am a child node");
childNode.setAttribute("attr", "value");

rootNode.appendChild(childNode);
document.appendChild(rootNode);

Answer 2

I'm assuming that you mean that the properties/structure was generated through the classes/beans themselves? If so, then the answer is no [without an third party component]. I've used XStream before, and that is about the closest that I've gotten to .NET's XML Class serialization.