dom解析

1.解析
第一步：获取document
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
Document doc = null;
File file = new File(xmlFile);
DocumentBuilder db;

// 校验xml文件是否格式良好
SchemaFactory sf = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
Source source = new StreamSource(new File(xmlSchemaFile));
Schema schema = sf.newSchema(source);
javax.xml.validation.Validator validator = schema.newValidator();
validator.validate(new StreamSource(new File(xmlFile)));

db = dbf.newDocumentBuilder();
doc = db.parse(xmlFile);
return doc;

第二步：获取root
Element root = doc.getDocumentElement();
第三步：获取信息
//获取子节点集合，并转换为element
NodeList actions = root.getElementsByTagName("action");
Element actionElement = (Element)actions.item(i);
//获取节点值
Text message = (Text)actionElement.getFirstChild();
//获取节点属性
String para = actionElement.getAttribute("para");
//获取节点名
String tagName = actionElement.getTagName();
//获取父节点
Element el = (Element)(actionElement.getParentNode());

2。保存
第一步：构造document
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = db = dbf.newDocumentBuilder();
// 新建一个空文档
Document doc = db.newDocument();
第二步：创建节点
Element root = doc.createElement("actions");
第三步：加入节点
Element actionElement = doc.createElement("action");
root.appendChild(actionElement);
第四步：给节点赋值
//节点值
Text tName = doc.createTextNode(action.getName());
nameElement.appendChild(tName);
//节点属性
actionElement.setAttribute("test","test");
第五步：将dom写入xml
TransformerFactory tFactory = TransformerFactory.newInstance();
Transformer transformer = tFactory.newTransformer();
Properties properties = transformer.getOutputProperties();
properties.setProperty(OutputKeys.ENCODING, encoding);
properties.setProperty(OutputKeys.METHOD, "xml");
transformer.setOutputProperties(properties);

// 创建一个DOMSource对象,该构造函数的参数可以是一个Document对象
DOMSource source = new DOMSource(doc);
// 创建XSLT引擎的输出对象，这里将输出写如文件
File file = new File(fileName);
StreamResult result = new StreamResult(file);

// 执行DOM文档到XML文件的转换
transformer.transform(source, result);

// 将输出文件的路径返回
return file.getAbsolutePath();