Android xml的3种解析方式

1.Dom

原理 就是把整个文档加载到内存 生成一个树状结构  dom tree

优点 可以修改文档

缺点 比较占用内存

@Testpublic void domParseTest() throws Exception{//①获取DocumentBuilderFactoryDocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();//②获取DocumentBuilderDocumentBuilder documentBuilder = builderFactory.newDocumentBuilder();//③获取DocumentDocument document = documentBuilder.parse("book.xml");//通过节点的名字 找到所有的同名的节点NodeList nodeList = document.getElementsByTagName("对应的名字");Node item = nodeList.item(0);//通过节点获取节点的内容String textContent = item.getTextContent();System.out.println("textConent==="+textContent);}

通过dom修改文档

public void domModifyTest() throws Exception{//获取DocumentBuilderFactoryDocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();//获取DocumentBuilderDocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();//通过DocumentBuilder 解析文件 拿到document对象Document document = documentBuilder.parse("book.xml");//找到售价节点NodeList nodeList = document.getElementsByTagName("price");Node node = nodeList.item(0);//设置文本内容node.setTextContent("20.00");//transformerTransformerFactory transformerFactory = TransformerFactory.newInstance();//通过工厂获得transformerTransformer transformer = transformerFactory.newTransformer();//通过transformer 把内存中的修改保存到文件中//指定数据源  把刚解析出来的document对象作为数据源Source arg0 = new DOMSource(document);//指定 修改之后保存结果的对象    创建一个StreamResult(流结果) 保存到本地文件 book.xmlResult arg1 = new StreamResult("book.xml");transformer.transform(arg0, arg1);}

2.sax

一个元素一个元素的解析优点 占用内存小 随时可以停下

步骤思路:

①SaxParserFactory

② 获取SAXParser

③ 获取XMLReader

④ 给XMLReader设置处理器 setContentHandler

⑤ 开始解析

public class SaxParserTest {@Testpublic void saxParse() throws Exception {// ①获取SaxParserFactorySAXParserFactory parserFactory = SAXParserFactory.newInstance();// ②获取SaxParserSAXParser parser = parserFactory.newSAXParser();// ③通过SaxParser获取xmlReaderXMLReader xmlReader = parser.getXMLReader();// 给xmlreader添加内容处理程序// xmlReader.setContentHandler(new MyHandler());xmlReader.setContentHandler(new DefaultHandler() {int count = 0;boolean isAuthor = false;@Overridepublic void characters(char[] ch, int start, int length)throws SAXException {if (count == 2 && isAuthor) {System.out.println("文本内容==="+ new String(ch, start, length));// count = 0;}}@Overridepublic void startDocument() throws SAXException {}@Overridepublic void startElement(String uri, String localName,String qName, Attributes atts) throws SAXException {// System.out.println("解析到开始标签=========<"+qName+">");if ("author"".equals(qName)) {count++;isAuthor = true;}}@Overridepublic void endElement(String uri, String localName, String qName)throws SAXException {if ("author".equals(qName)) {isAuthor = false;}}@Overridepublic void endDocument() throws SAXException {}});xmlReader.parse("book.xml");}

3.pull解析

优点 占用内存小 随时可以停下

public class XMLPullParserTest {@Testpublic void pullTest() throws Exception {//声明一个arraylist用来存放解析的结果ArrayList<Book> books = null;int count = 0;//创建一本书 用来保存 每一个<book></book>节点中的内容Book book = null;XmlPullParserFactory factory = XmlPullParserFactory.newInstance();XmlPullParser xpp = factory.newPullParser();// 给解析器设置输入源 第一个参数 输入流 第二个参数 编码集xpp.setInput(new FileInputStream("book.xml"), "utf-8");//通过getEventType 获取当前解析到的节点类型int eventType = xpp.getEventType();

while (eventType != XmlPullParser.END_DOCUMENT) {switch (eventType) {//处理开始标签case XmlPullParser.START_TAG:if("bookshelf".equals(xpp.getName())){//解析到<书架> 准备集合books = new ArrayList<Book>();}else if("book".equals(xpp.getName())){//new book() 准备一本书book = new Book();}else if("booktitle".equals(xpp.getName())){// 给book.title赋值book.title = xpp.nextText();}else if("author".equals(xpp.getName())){// 给book.author赋值book.author = xpp.nextText();}else if("price".equals(xpp.getName())){// 给book.price赋值book.price = xpp.nextText();}break;//处理结束标签case XmlPullParser.END_TAG:if("书".equals(xpp.getName())){//把book放到集合中books.add(book);//给book置空book = null;count++;}break;}//// 不断的解析//if(count == 1){//break;//}//调用xpp.next() 解析下一个元素 用eventType 接收返回值eventType = xpp.next();}//遍历集合for(Book book1:books){System.out.println(book1);}}}