XML和JSON是两种常用的数据交换格式。虽然对于XML和JSON的各种操作，仅仅是常用的工具jar包的使用，没有什么技术含量，但鉴于这两种数据格式的普遍使用，还是拿出一点时间，进行一下简单总结。 # XML XML官网：[http://www.xml.com/](http://www.xml.com/) XML保留字符有5个：&、>、<、'、""。 对于XML的解析方式，有两种：DOM方式和SAX方式。DOM是读入内存之后进行各种操作，SAX是流式操作、一次性的。其他的一些工具jar包，比如JDOM、DOM4J，都是对于这两种方式的高层次封装。 **参考网址：** [http://wenku.baidu.com/link?url=7VjI_4xMpWdV2O82WrNI2KO2UNuhefJYeGYe17QUmH89Nlc9NH20oVr8ZMJ2w1RSvphm5UE88L4FhB4fJgCcV4HldRlJsP9n_o1n1r7gunG](http://wenku.baidu.com/link?url=7VjI_4xMpWdV2O82WrNI2KO2UNuhefJYeGYe17QUmH89Nlc9NH20oVr8ZMJ2w1RSvphm5UE88L4FhB4fJgCcV4HldRlJsP9n_o1n1r7gunG) [http://inotgaoshou.iteye.com/blog/1012188](http://inotgaoshou.iteye.com/blog/1012188) **DOM图示：**  **SAX图示：**  **演示代码：** ~~~ import java.io.File; import java.util.Stack; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.SAXParser; import javax.xml.parsers.SAXParserFactory; import org.w3c.dom.Attr; import org.w3c.dom.Comment; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.NamedNodeMap; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import org.xml.sax.Attributes; import org.xml.sax.SAXException; import org.xml.sax.helpers.DefaultHandler; /** * 演示两种XML的解析方式：DOM和SAX * * 至于JDOM和DOM4J，只是在这两种方式之上的更高层次的封装 * */ public class XmlDemo { public static void main(String[] args) throws Exception { XmlDemo xmlDemo = new XmlDemo(); // DOM方式 DomDemo domDemo = xmlDemo.new DomDemo("src/main/java/com/cl/roadshow/java/xml/people.xml"); domDemo.iterateByName("PERSON"); domDemo.recursiveElement(); // SAX方式 SaxDemo saxDemo = xmlDemo.new SaxDemo("src/main/java/com/cl/roadshow/java/xml/people.xml"); saxDemo.showEvents(); saxDemo.parseDocument(); } /** * DOM方式解析XML * */ class DomDemo { private String path; public DomDemo(String path) { this.path = path; } /** * 查询所有符合给到名称的Node，大小写敏感 * * @param tagName * @throws Exception */ public void iterateByName(String tagName) throws Exception { // 获得DOM解析器工厂 DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); // 获得具体的DOM解析器 DocumentBuilder db = dbf.newDocumentBuilder(); // 解析XML文档，获得Document对象（根结点） Document doc = db.parse(new File(path)); NodeList nodeList = doc.getElementsByTagName(tagName); for (int i = 0; i < nodeList.getLength(); i++) { Element element = (Element) nodeList.item(i); String content = element.getElementsByTagName("NAME").item(0).getFirstChild().getNodeValue(); System.out.println("name:" + content); content = element.getElementsByTagName("ADDRESS").item(0).getFirstChild().getNodeValue(); System.out.println("address:" + content); content = element.getElementsByTagName("TEL").item(0).getFirstChild().getNodeValue(); System.out.println("tel:" + content); content = element.getElementsByTagName("FAX").item(0).getFirstChild().getNodeValue(); System.out.println("fax:" + content); content = element.getElementsByTagName("EMAIL").item(0).getFirstChild().getNodeValue(); System.out.println("email:" + content); System.out.println("--------------------------------------"); } } /** * 从根节点开始，遍历XML的所有元素 * * @throws Exception */ public void recursiveElement() throws Exception { DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db = dbf.newDocumentBuilder(); Document doc = db.parse(new File(path)); // 获得根元素结点 Element root = doc.getDocumentElement(); parseElement(root); } /** * 递归方法 * * @param element */ private void parseElement(Element element) { String tagName = element.getNodeName(); NodeList children = element.getChildNodes(); System.out.print("<" + tagName); // element元素的所有属性所构成的NamedNodeMap对象，需要对其进行判断 NamedNodeMap map = element.getAttributes(); // 如果该元素存在属性 if (null != map) { for (int i = 0; i < map.getLength(); i++) { // 获得该元素的每一个属性 Attr attr = (Attr) map.item(i); String attrName = attr.getName(); String attrValue = attr.getValue(); System.out.print(" " + attrName + "=\"" + attrValue + "\""); } } System.out.print(">"); for (int i = 0; i < children.getLength(); i++) { Node node = children.item(i); // 获得结点的类型 short nodeType = node.getNodeType(); if (nodeType == Node.ELEMENT_NODE) { // 是元素，继续递归 parseElement((Element) node); } else if (nodeType == Node.TEXT_NODE) { // 递归出口 System.out.print(node.getNodeValue()); } else if (nodeType == Node.COMMENT_NODE) { System.out.print("<!--"); Comment comment = (Comment) node; // 注释内容 String data = comment.getData(); System.out.print(data); System.out.print("-->"); } } System.out.print("</" + tagName + ">"); } } /** * SAX方式解析XML * */ class SaxDemo { private String path; public SaxDemo(String path) { this.path = path; } public void showEvents() throws Exception { // 获得SAX解析器工厂实例 SAXParserFactory factory = SAXParserFactory.newInstance(); // 获得SAX解析器实例 SAXParser parser = factory.newSAXParser(); // 开始进行解析 parser.parse(new File(path), new EventHandler()); } public void parseDocument() throws Exception { // 获得SAX解析器工厂实例 SAXParserFactory factory = SAXParserFactory.newInstance(); // 获得SAX解析器实例 SAXParser parser = factory.newSAXParser(); // 开始进行解析 parser.parse(new File(path), new ParseHandler()); } /** * 演示SAX解析方式的事件驱动过程 * */ class EventHandler extends DefaultHandler { @Override public void startDocument() throws SAXException { System.out.println("\n--------------------------------------"); System.out.println("start document"); } @Override public void endDocument() throws SAXException { System.out.println("finish document"); System.out.println("--------------------------------------"); } @Override public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { System.out.println("start element"); } @Override public void endElement(String uri, String localName, String qName) throws SAXException { System.out.println("finish element"); } } /** * 演示用SAX方式解析PERSON节点的过程 * */ class ParseHandler extends DefaultHandler { private Stack<String> stack = new Stack<String>(); private String name; private String tel; @Override public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { stack.push(qName); for (int i = 0; i < attributes.getLength(); i++) { String attrName = attributes.getQName(i); String attrValue = attributes.getValue(i); System.out.println(attrName + "=" + attrValue); } } @Override public void characters(char[] ch, int start, int length) throws SAXException { String tag = stack.peek(); if ("NAME".equals(tag)) { name = new String(ch, start, length); } else if ("TEL".equals(tag)) { tel = new String(ch, start, length); } } @Override public void endElement(String uri, String localName, String qName) throws SAXException { stack.pop(); // 表示该元素已经解析完毕，需要从栈中弹出 if ("PERSON".equals(qName)) { System.out.println("NAME：" + name); System.out.println("TEL：" + tel); System.out.println(); } } } } } ~~~ # JSON JSON官网：[http://www.json.org/json-zh.html](http://www.json.org/json-zh.html) 对于JSON的解析，各种语言下都有 很多可用客户端，在Java下，fastjson是推荐使用的一种，快、强大、无依赖。 **代码演示：** ~~~ import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import com.alibaba.fastjson.JSON; import com.alibaba.fastjson.TypeReference; /** * fastjson 是一个性能很好的 Java 语言实现的 JSON 解析器和生成器，来自阿里巴巴的工程师开发 * * * 主要特点：比其它任何基于Java的解析器和生成器更快，包括jackson；强大；零依赖 * */ public class FastjsonDemo { public static void main(String[] args) { // 将JSON和JavaBean对象互相转换 Person person = new Person(1, "张三", null); String jsonString = JSON.toJSONString(person); System.out.println(jsonString); person = JSON.parseObject(jsonString, Person.class); System.out.println(person.getName()); System.out.println("--------------------------------------"); // 将JSON字符串转化成List<JavaBean>对象 Person person1 = new Person(1, "fastjson1", 11); Person person2 = new Person(2, "fastjson2", 22); List<Person> persons = new ArrayList<Person>(); persons.add(person1); persons.add(person2); jsonString = JSON.toJSONString(persons); System.out.println("json字符串:" + jsonString); persons = JSON.parseArray(jsonString, Person.class); System.out.println(persons.toString()); System.out.println("--------------------------------------"); // 将JSON字符串转化成List<String>对象 List<String> list1 = new ArrayList<String>(); list1.add("fastjson1"); list1.add("fastjson2"); list1.add("fastjson3"); jsonString = JSON.toJSONString(list1); System.out.println(jsonString); List<String> list2 = JSON.parseObject(jsonString, new TypeReference<List<String>>() { }); System.out.println("list2：" + list2.toString()); System.out.println("--------------------------------------"); // JSON<Map<String,Object>>对象 Map<String, Object> map = new HashMap<String, Object>(); map.put("key1", "value1"); map.put("key2", "value2"); Map<String, Object> map2 = new HashMap<String, Object>(); map2.put("key1", 1); map2.put("key2", 2); List<Map<String, Object>> list3 = new ArrayList<Map<String, Object>>(); list3.add(map); list3.add(map2); jsonString = JSON.toJSONString(list3); System.out.println("json字符串:" + jsonString); List<Map<String, Object>> list4 = JSON.parseObject(jsonString, new TypeReference<List<Map<String, Object>>>() { }); System.out.println("list4：" + list4.toString()); } } class Person { private Integer id; private String name; private Integer age; public Person() { } public Person(Integer id, String name, Integer age) { super(); this.id = id; this.name = name; this.age = age; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } @Override public String toString() { StringBuilder sb = new StringBuilder(); sb.append("ID:").append(id); sb.append("-Name:").append(name); sb.append("-Age:").append(age); return sb.toString(); } } ~~~