Java XML解析之 JAXP

        JAXP严格来说我觉得只能算是一个解析XML的抽象层，Java应用可以通过Jaxp支持多种处理xml的底层实现，在API上沿用了w3c的Dom和Sax接口，乏善可陈。事实上Dom4j通过支持Jaxp也可以拥有Jaxp这层抽象的优点，不明白sun为什么不在Jaxp这层抽象上定义更好用的接口。 

1、使用Sax接口

SAXParserFactory factory = SAXParserFactory.newInstance();
SAXParser parser = factory.newSAXParser();
parser.parse(new File(args[0]), new MyHandler());

//定义Sax回调实现
class MyHandler extends DefaultHandler {
    // SAX callback implementations from ContentHandler, ErrorHandler, etc.
}

2、使用Dom接口

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();   
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(in);

//一个遍历的简单示例

public void printTree(Node node, String pre)
    ...{
        switch (node.getNodeType())
        ...{
        case Node.ATTRIBUTE_NODE:
            System.out.print(pre + node.getNodeName() + " = ");
            System.out.println(node.getNodeValue());
            break;
        case Node.DOCUMENT_NODE:
            Document doc = (Document) node;
            printTree(doc.getDocumentElement(), "");
            break;
        case Node.ELEMENT_NODE:
            System.out.println(pre + node.getNodeName());
            NamedNodeMap map = node.getAttributes();
            for (int i = 0; i < map.getLength(); i++)
            ...{
                Node attr = map.item(i);
                printTree(attr, pre);
            }
            NodeList list = node.getChildNodes();
            for (int i = 0; i < list.getLength(); i++)
            ...{
                Node child = list.item(i);
                printTree(child, pre + "  ");
            }
            break;
        case Node.TEXT_NODE:
            if (node.getTextContent() == null
                    || node.getTextContent().trim().equals(""))
            ...{
                break;
            }
            System.out.println(pre + node.getTextContent());
            break;
        default:
            break;
        }        
    }

输出Document

 

    public void write(Document doc, OutputStream out)
            throws TransformerException, UnsupportedEncodingException,
            IOException
    ...{
        TransformerFactory tfactory = TransformerFactory.newInstance();
        Transformer former = tfactory.newTransformer();
        Source source = new DOMSource(doc);
        StringWriter buffer = new StringWriter();
        StreamResult result = new StreamResult(buffer);
        former.transform(source, result);
        out.write(buffer.toString().getBytes("GBK"));
    }

 

 上面的DefaultHandler和Document都是w3c定义的，对Java来说都算不上友好。