java中xml的解析方式有许多，有java自带的DOM、SAX，android中的PULL，其它的还有DOM4J、JDOM等。
本文简要讲述DOM、SAX、PULL三种方式。
1.DOM方法
缺点：此方法会将所有数据都读取到内存中，内存消耗大，数据量太大容易造成OOM，而且此方法的效率较低，所以不建议在移动开发中使用。
优点：以树形的结构访问，容易理解，编码简单，可随机访问所需要的内容。
2.SAX方法：
从开头顺序读取直至结尾，读取和处理同步。
缺点：编码难度较大
优点：解析快，占用内存小，适合在移动设备上使用
3.PULL方法：
此方法与SAX方法类似，适合在移动设备中使用，android系统内部默认使用此方法。
与SAX的区别是，此方法能随时结束解析，而SAX不能。
先展示一下接下来要解析的xml数据和对应的类：
book.xml
冰与火之歌 乔治马丁 2014 89 安徒生童话 2004 77 English
Book.java
public class Book { private String id; private String name; private String author; private String year; private String price; private String language; public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getAuthor() { return author; } public void setAuthor(String author) { this.author = author; } public String getYear() { return year; } public void setYear(String year) { this.year = year; } public String getPrice() { return price; } public void setPrice(String price) { this.price = price; } public String getLanguage() { return language; } public void setLanguage(String language) { this.language = language; } @Override public String toString() { return "Book{" + "id='" + id + '\'' + ", name='" + name + '\'' + ", author='" + author + '\'' + ", year='" + year + '\'' + ", price='" + price + '\'' + ", language='" + language + '\'' + '}'; }} 1、PULL
解析：
public static ArrayListgetBooks(InputStream is) throws Exception { ArrayList books = null; Book book = null; // 创建一个xml解析的工厂 XmlPullParserFactory factory = XmlPullParserFactory.newInstance(); // 获得xml解析类的引用 XmlPullParser parser = factory.newPullParser(); parser.setInput(is, "UTF-8"); // 获得事件的类型 int eventType = parser.getEventType(); while (eventType != XmlPullParser.END_DOCUMENT) { switch (eventType) { case XmlPullParser.START_DOCUMENT: books = new ArrayList<>(); break; case XmlPullParser.START_TAG: if ("book".equals(parser.getName())) { book = new Book(); // 取出属性值 String id = parser.getAttributeValue(0); book.setId(id); } else if ("name".equals(parser.getName())) { String name = parser.nextText();// 获取该节点的内容 Show.log("name:"+name); book.setName(name); } else if ("author".equals(parser.getName())) { String author = parser.nextText(); book.setAuthor(author); }else if("year".equals(parser.getName())){ String year=parser.nextText(); book.setYear(year); }else if ("price".equals(parser.getName())){ String price=parser.nextText(); book.setPrice(price); }else if("language".equals(parser.getName())){ String language=parser.nextText(); book.setLanguage(language); } break; case XmlPullParser.END_TAG: if ("book".equals(parser.getName())) { books.add(book); book = null; } break; } eventType = parser.next(); } return books; }
生成：
public static void save(Listbooks, OutputStream out) throws Exception { XmlSerializer serializer = Xml.newSerializer(); serializer.setOutput(out, "UTF-8"); serializer.startDocument("UTF-8", true); serializer.startTag(null, "bookstore"); for (Book book : books) { Show.log(book.toString()); serializer.startTag(null, "book"); serializer.attribute(null, "id", book.getId() + ""); serializer.startTag(null, "name"); serializer.text(book.getName()); serializer.endTag(null, "name"); serializer.startTag(null, "author"); serializer.text(book.getAuthor() + ""); serializer.endTag(null, "author"); serializer.startTag(null,"year"); serializer.text(book.getYear()); serializer.endTag(null,"year"); serializer.startTag(null,"language"); serializer.text(book.getLanguage()+""); serializer.endTag(null,"language"); serializer.endTag(null, "book"); } serializer.endTag(null, "bookstore"); serializer.endDocument(); }
2、DOM
解析：
public static void domXmlParser() { ArrayList bookLists = new ArrayList (); DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); try { DocumentBuilder db = dbf.newDocumentBuilder(); Document document = db.parse("book.xml"); NodeList bookList = document.getElementsByTagName("book"); for (int i = 0; i < bookList.getLength(); i++) { Node book = bookList.item(i); Book bookEntity = new Book(); NamedNodeMap attrs = book.getAttributes(); for (int j = 0; j < attrs.getLength(); j++) { Node attr = attrs.item(j); if (attr.getNodeName().equals("id")) { bookEntity.setId(attr.getNodeValue()); } } NodeList childNodes = book.getChildNodes(); for (int k = 0; k < childNodes.getLength(); k++) { if (childNodes.item(k).getNodeType() == Node.ELEMENT_NODE) { String name = childNodes.item(k).getNodeName(); String value = childNodes.item(k).getFirstChild().getNodeValue(); if (name.equals("name")) { bookEntity.setName(value); } else if (name.equals("author")) { bookEntity.setAuthor(value); } else if (name.equals("year")) { bookEntity.setYear(value); } else if (name.equals("price")) { bookEntity.setPrice(value); } else if (name.equals("language")) { bookEntity.setLanguage(value); } } } bookLists.add(bookEntity); bookEntity = null; } } catch (ParserConfigurationException e) { e.printStackTrace(); } catch (SAXException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } }
生成：
public void DOMCreateXML() { DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db = null; try { db = dbf.newDocumentBuilder(); } catch (ParserConfigurationException e) { e.printStackTrace(); } Document document = db.newDocument(); document.setXmlStandalone(true); Element bookstore = document.createElement("bookStore"); Element book = document.createElement("book"); Element name = document.createElement("name"); name.setTextContent("小王子"); book.appendChild(name); book.setAttribute("id", "1"); bookstore.appendChild(book); document.appendChild(bookstore); TransformerFactory tff = TransformerFactory.newInstance(); try { Transformer tf = tff.newTransformer(); tf.setOutputProperty(OutputKeys.INDENT, "yes"); tf.transform(new DOMSource(document), new StreamResult(new File( "books1.xml"))); } catch (TransformerConfigurationException e) { e.printStackTrace(); } catch (TransformerException e) { e.printStackTrace(); } }
3、SAX
解析：
public class SAXParserHandler extends DefaultHandler { String value = null; Book book = null; private ArrayList bookList = new ArrayList (); public ArrayList getBookList() { return bookList; } int bookIndex = 0; /** * 用来标识解析开始 */ @Override public void startDocument() throws SAXException { super.startDocument(); } /** * 用来标识解析结束 */ @Override public void endDocument() throws SAXException { super.endDocument(); } /** * 解析xml元素 */ @Override public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { super.startElement(uri, localName, qName, attributes); if (qName.equals("book")) { bookIndex++; book = new Book(); String value = attributes.getValue("id"); int num = attributes.getLength(); for(int i = 0; i < num; i++){ if (attributes.getQName(i).equals("id")) { book.setId(attributes.getValue(i)); } } } } @Override public void endElement(String uri, String localName, String qName) throws SAXException { super.endElement(uri, localName, qName); if (qName.equals("book")) { bookList.add(book); book = null; } else if (qName.equals("name")) { book.setName(value); } else if (qName.equals("author")) { book.setAuthor(value); } else if (qName.equals("year")) { book.setYear(value); } else if (qName.equals("price")) { book.setPrice(value); } else if (qName.equals("language")) { book.setLanguage(value); } } @Override public void characters(char[] ch, int start, int length) throws SAXException { // TODO Auto-generated method stub super.characters(ch, start, length); String temp = new String(ch, start, length); if (!temp.trim().equals("")) { value = temp; } }} public static void saxXmlParser(){ SAXParserFactory factory = SAXParserFactory.newInstance(); try { SAXParser parser = factory.newSAXParser(); SAXParserHandler handler = new SAXParserHandler(); parser.parse("book.xml", handler); } catch (ParserConfigurationException e) { e.printStackTrace(); } catch (SAXException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } 生成：
public void SAXCreateXML() { SAXTransformerFactory tff = (SAXTransformerFactory) SAXTransformerFactory .newInstance(); try { TransformerHandler handler = tff.newTransformerHandler(); Transformer tr = handler.getTransformer(); tr.setOutputProperty(OutputKeys.ENCODING, "UTF-8"); tr.setOutputProperty(OutputKeys.INDENT, "yes"); File f = new File("books2.xml"); if (!f.exists()) { f.createNewFile(); } Result result = new StreamResult(new FileOutputStream(f)); handler.setResult(result); handler.startDocument(); AttributesImpl attr = new AttributesImpl(); handler.startElement("", "", "bookstore", attr); attr.clear(); attr.addAttribute("", "", "id", "", "1"); handler.startElement("", "", "book", attr); attr.clear(); handler.startElement("", "", "name", attr); handler.characters("小王子".toCharArray(), 0, "小王子".length()); handler.endElement("", "", "name"); handler.endElement("", "", "book"); handler.endElement("", "", "bookstore"); handler.endDocument(); } catch (TransformerConfigurationException e) { e.printStackTrace(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } catch (SAXException e) { e.printStackTrace(); } }