XML

XML
1）<![CDATA[內容]]> 原始內容直接輸出
2）DTD
_1當引用文件在本地時 <!DOCTYPE 文檔根節點 SYSTEM "DTD文件的URL">
當引用的文件是一個公共文件時 <!DOCTYPE 文檔根節點 PUBLIC "DTD名稱" "DTD文件的URL">
_2引用實體，主要在XML文檔中應用 <!ENTITY bookname "javaeb"> 引用實體：&bookname;
參數實體，主要在DTD中應用 <!ENTITY % TAG_NAMES "NAME|EMAIL|PHONE"> 引用實體：%TAG_NAMES;
3)XML編程（CRUD）create read update delete
_1DOM和sax解析方法的區別：dom解析的優點是對文檔crud比較方便，缺點是佔用內存較大；sax解析的優點是佔用內存小，解析速度快，缺點是隻適合做文檔的讀取，不適合做文檔的crud
_2jaxp解析

Dom解析：

<pre name="code" class="java">		<span style="font-family: Arial, Helvetica, sans-serif;">//1.創建工廠</span>

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();//2.得到Dom解析器DocumentBuilder builder = factory.newDocumentBuilder();//3.解析xml文檔，得到代表文檔的documentDocument document = builder.parse("src/student/practice/xml/book.xml");//........（crud） //注意最後要從內存中寫出//把更新後內存寫回到xml文檔TransformerFactory tff = TransformerFactory.newInstance();Transformer tf = tff.newTransformer();tf.transform(new DOMSource(document), new StreamResult(new FileOutputStream("src/student/practice/xml/book.xml")));

SAX解析：

		//得到解析工廠
		SAXParserFactory factory = SAXParserFactory.newInstance();
		//得到解析器
		SAXParser sp = factory.newSAXParser();
		//得到讀取器
		XMLReader reader = sp.getXMLReader();
		//設置內容處理器
		reader.setContentHandler(解析器類對象);
		//讀取xml文檔內容
		reader.parse("src/student/practice/xml/book.xml");

_3Dom4j解析（dom4j包，需要jaxen-1.1-beta包支持）

		SAXReader reader = new SAXReader();
		Document document = reader.read(new File(filepath));//有時候也會亂碼，讀取時要把字節編碼,如下注釋代碼：
		//Document document = reader.read(new InputStreamReader(new FileInputStream(filepath),"utf-8"));
		Element root = document.getRootElement();
		...
		//XMLWriter writer = new XMLWriter(new FileWriter(filepath));//默認採用gb2312寫入，可能會亂碼

		OutputFormat format = OutputFormat.createPrettyPrint();
		format.setEncoding("gb2312");//內存中documentgb2312，gb2312文檔寫入		
		XMLWriter writer = new XMLWriter(new OutputStreamWriter(new FileOutputStream(filepath), "gb2312"), format);
		//這個不亂碼是碰巧，因爲控制OutputStreamWriter查gb2312碼錶，但是FileOutputStream仍然默認是gb2312，所以如果全是utf-8，依然會亂碼
		//可以採用以下代碼：
		//XMLWriter writer = new XMLWriter(new FileOutputStream(filepath), "gb2312"), format);
		writer.write(document);
		writer.close();

_4xpath

		SAXReader reader = new SAXReader();//xpath學習見文檔
		Document document = reader.read(new File(filepath));
		String value = document.selectSingleNode("//@name").getText();

4）Schema
名稱空間，約束語法等