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
<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
<book id="1">
<name>冰与火之歌</name>
<author>乔治马丁</author>
<year>2014</year>
<price>89</price>
</book>
<book id="2">
<name>安徒生童话</name>
<year>2004</year>
<price>77</price>
<language>English</language>
</book>
</bookstore>
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 ArrayList<Book> getBooks(InputStream is) throws Exception {
ArrayList<Book> 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(List<Book> books, 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<Book> bookLists = new ArrayList<Book>();
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<Book> bookList = new ArrayList<Book>();
public ArrayList<Book> 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();
}
}
