XML現在已經成爲一種通用的數據交換格式,平臺的無關性使得很多場合都需要用到XML。本文將詳細介紹用Java解析XML的四種方法
在做一般的XML數據交換過程中，我更樂意傳遞XML字符串，而不是格式化的XML Document。這就涉及到XML字符串和Xml Document的轉換問題，說白了這是個很簡單的問題，本文就各種XML解析器分別列舉如下，以方便自己今後查閱。
=======================哈哈====================================
一、使用最原始的javax.xml.parsers，標準的jdk api
// 字符串轉XML
String xmlStr = "......";
StringReader sr = new StringReader(xmlStr);
InputSource is = new InputSource(sr);
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder=factory.newDocumentBuilder();
Document doc = builder.parse(is);
//XML轉字符串
TransformerFactory tf = TransformerFactory.newInstance();
Transformer t = tf.newTransformer();
t.setOutputProperty("encoding","GB23121");//解決中文問題，試過用GBK不行
ByteArrayOutputStream bos = new ByteArrayOutputStream();
t.transform(new DOMSource(doc), new StreamResult(bos));
String xmlStr = bos.toString();
這裏的XML DOCUMENT爲org.w3c.dom.Document
二、使用dom4j後程序變得更簡單
// 字符串轉XML
String xmlStr = "......";
Document document = DocumentHelper.parseText(xmlStr);
// XML轉字符串
Document document = ...;
String text = document.asXML();
這裏的XML DOCUMENT爲org.dom4j.Document
三、使用JDOM
JDOM的處理方式和第一種方法處理非常類似
//字符串轉XML
String xmlStr = ".....";
StringReader sr = new StringReader(xmlStr);
InputSource is = new InputSource(sr);
Document doc = (new SAXBuilder()).build(is);
//XML轉字符串
Format format = Format.getPrettyFormat();
format.setEncoding("gb2312");//設置xml文件的字符爲gb2312，解決中文問題
XMLOutputter xmlout = new XMLOutputter(format);
ByteArrayOutputStream bo = new ByteArrayOutputStream();
xmlout.output(doc,bo);
String xmlStr = bo.toString();
這裏的XML DOCUMENT爲org.jdom.Document
四、JavaScript中的處理
//字符串轉XML
var xmlStr = ".....";
var xmlDoc = new ActiveXObject("Microsoft.XMLDOM");
xmlDoc.async=false;
xmlDoc.loadXML(xmlStr);
//可以處理這個xmlDoc了
var name = xmlDoc.selectSingleNode("/person/name");
alert(name.text);
//XML轉字符串
var xmlDoc = ......;
var xmlStr = xmlDoc.xml
這裏的XML DOCUMENT爲javascript版的XMLDOM
=============================我是黃金的分割線===========================
XML現在已經成爲一種通用的數據交換格式,它的平臺無關性,語言無關性,系統無關性,給數據集成與交互帶來了極大的方便。對於XML本身的語法知識與技術細節,需要閱讀相關的技術文獻,這裏麪包括的內容有DOM(Document Object Model),DTD(Document Type Definition),SAX(Simple API for XML),XSD(Xml Schema Definition),XSLT(Extensible Stylesheet Language Transformations),具體可參閱w3c官方網站文檔http://www.w3.org獲取更多信息。
XML在不同的語言裏解析方式都是一樣的,只不過實現的語法不同而已。基本的解析方式有兩種,一種叫SAX，另一種叫DOM。SAX是基於事件流的解析,DOM是基於XML文檔樹結構的解析。假設我們XML的內容和結構如下:
複製代碼代碼如下:
<?xml version="1.0" encoding="UTF-8"?>
<employees>
<employee>
<name>ddviplinux</name>
<sex>m</sex>
<age>30</age>
</employee>
</employees>
本文使用JAVA語言來實現DOM與SAX的XML文檔生成與解析。
首先定義一個操作XML文檔的接口XmlDocument 它定義了XML文檔的建立與解析的接口。
複製代碼代碼如下:
package com.alisoft.facepay.framework.bean;
/**
*
* @author hongliang.dinghl
* 定義XML文檔建立與解析的接口
*/
public interface XmlDocument {
/**
* 建立XML文檔
* @param fileName 文件全路徑名稱
*/
public void createXml(String fileName);
/**
* 解析XML文檔
* @param fileName 文件全路徑名稱
*/
public void parserXml(String fileName);
}
1.DOM生成和解析XML文檔
爲 XML 文檔的已解析版本定義了一組接口。解析器讀入整個文檔，然後構建一個駐留內存的樹結構，然後代碼就可以使用 DOM 接口來操作這個樹結構。優點：整個文檔樹在內存中，便於操作；支持刪除、修改、重新排列等多種功能；缺點：將整個文檔調入內存（包括無用的節點），浪費時間和空間；使用場合：一旦解析了文檔還需多次訪問這些數據；硬件資源充足（內存、CPU）。
複製代碼代碼如下:
package com.alisoft.facepay.framework.bean;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
/**
*
* @author hongliang.dinghl
* DOM生成與解析XML文檔
*/
public class DomDemo implements XmlDocument {
private Document document;
private String fileName;
public void init() {
try {
DocumentBuilderFactory factory = DocumentBuilderFactory
.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
this.document = builder.newDocument();
} catch (ParserConfigurationException e) {
System.out.println(e.getMessage());
}
}
public void createXml(String fileName) {
Element root = this.document.createElement("employees");
this.document.appendChild(root);
Element employee = this.document.createElement("employee");
Element name = this.document.createElement("name");
name.appendChild(this.document.createTextNode("丁宏亮"));
employee.appendChild(name);
Element sex = this.document.createElement("sex");
sex.appendChild(this.document.createTextNode("m"));
employee.appendChild(sex);
Element age = this.document.createElement("age");
age.appendChild(this.document.createTextNode("30"));
employee.appendChild(age);
root.appendChild(employee);
TransformerFactory tf = TransformerFactory.newInstance();
try {
Transformer transformer = tf.newTransformer();
DOMSource source = new DOMSource(document);
transformer.setOutputProperty(OutputKeys.ENCODING, "gb2312");
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
PrintWriter pw = new PrintWriter(new FileOutputStream(fileName));
StreamResult result = new StreamResult(pw);
transformer.transform(source, result);
System.out.println("生成XML文件成功!");
} catch (TransformerConfigurationException e) {
System.out.println(e.getMessage());
} catch (IllegalArgumentException e) {
System.out.println(e.getMessage());
} catch (FileNotFoundException e) {
System.out.println(e.getMessage());
} catch (TransformerException e) {
System.out.println(e.getMessage());
}
}
public void parserXml(String fileName) {
try {
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
Document document = db.parse(fileName);
NodeList employees = document.getChildNodes();
for (int i = 0; i < employees.getLength(); i++) {
Node employee = employees.item(i);
NodeList employeeInfo = employee.getChildNodes();
for (int j = 0; j < employeeInfo.getLength(); j++) {
Node node = employeeInfo.item(j);
NodeList employeeMeta = node.getChildNodes();
for (int k = 0; k < employeeMeta.getLength(); k++) {
System.out.println(employeeMeta.item(k).getNodeName()
+ ":" + employeeMeta.item(k).getTextContent());
}
}
}
System.out.println("解析完畢");
} catch (FileNotFoundException e) {
System.out.println(e.getMessage());
} catch (ParserConfigurationException e) {
System.out.println(e.getMessage());
} catch (SAXException e) {
System.out.println(e.getMessage());
} catch (IOException e) {
System.out.println(e.getMessage());
}
}
}
2.SAX生成和解析XML文檔
爲解決DOM的問題，出現了SAX。SAX ，事件驅動。當解析器發現元素開始、元素結束、文本、文檔的開始或結束等時，發送事件，程序員編寫響應這些事件的代碼，保存數據。優點：不用事先調入整個文檔，佔用資源少；SAX解析器代碼比DOM解析器代碼小，適於Applet，下載。缺點：不是持久的；事件過後，若沒保存數據，那麼數據就丟了；無狀態性；從事件中只能得到文本，但不知該文本屬於哪個元素；使用場合：Applet;只需XML文檔的少量內容，很少回頭訪問；機器內存少；
Java代碼
複製代碼代碼如下:
package com.alisoft.facepay.framework.bean;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
/**
*
* @author hongliang.dinghl
* SAX文檔解析
*/
public class SaxDemo implements XmlDocument {
public void createXml(String fileName) {
System.out.println("<<"+filename+">>");
}
public void parserXml(String fileName) {
SAXParserFactory saxfac = SAXParserFactory.newInstance();
try {
SAXParser saxparser = saxfac.newSAXParser();
InputStream is = new FileInputStream(fileName);
saxparser.parse(is, new MySAXHandler());
} catch (ParserConfigurationException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
class MySAXHandler extends DefaultHandler {
boolean hasAttribute = false;
Attributes attributes = null;
public void startDocument() throws SAXException {
System.out.println("文檔開始打印了");
}
public void endDocument() throws SAXException {
System.out.println("文檔打印結束了");
}
public void startElement(String uri, String localName, String qName,
Attributes attributes) throws SAXException {
if (qName.equals("employees")) {
return;
}
if (qName.equals("employee")) {
System.out.println(qName);
}
if (attributes.getLength() > 0) {
this.attributes = attributes;
this.hasAttribute = true;
}
}
public void endElement(String uri, String localName, String qName)
throws SAXException {
if (hasAttribute && (attributes != null)) {
for (int i = 0; i < attributes.getLength(); i++) {
System.out.println(attributes.getQName(0)
+ attributes.getValue(0));
}
}
}
public void characters(char[] ch, int start, int length)
throws SAXException {
System.out.println(new String(ch, start, length));
}
}
package com.alisoft.facepay.framework.bean;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
/**
*
* @author hongliang.dinghl
* SAX文檔解析
*/
public class SaxDemo implements XmlDocument {
public void createXml(String fileName) {
System.out.println("<<"+filename+">>");
}
public void parserXml(String fileName) {
SAXParserFactory saxfac = SAXParserFactory.newInstance();
try {
SAXParser saxparser = saxfac.newSAXParser();
InputStream is = new FileInputStream(fileName);
saxparser.parse(is, new MySAXHandler());
} catch (ParserConfigurationException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
class MySAXHandler extends DefaultHandler {
boolean hasAttribute = false;
Attributes attributes = null;
public void startDocument() throws SAXException {
System.out.println("文檔開始打印了");
}
public void endDocument() throws SAXException {
System.out.println("文檔打印結束了");
}
public void startElement(String uri, String localName, String qName,
Attributes attributes) throws SAXException {
if (qName.equals("employees")) {
return;
}
if (qName.equals("employee")) {
System.out.println(qName);
}
if (attributes.getLength() > 0) {
this.attributes = attributes;
this.hasAttribute = true;
}
}
public void endElement(String uri, String localName, String qName)
throws SAXException {
if (hasAttribute && (attributes != null)) {
for (int i = 0; i < attributes.getLength(); i++) {
System.out.println(attributes.getQName(0)
+ attributes.getValue(0));
}
}
}
public void characters(char[] ch, int start, int length)
throws SAXException {
System.out.println(new String(ch, start, length));
}
}
3.DOM4J生成和解析XML文檔
DOM4J 是一個非常非常優秀的Java XML API，具有性能優異、功能強大和極端易用使用的特點，同時它也是一個開放源代碼的軟件。如今你可以看到越來越多的 Java 軟件都在使用 DOM4J 來讀寫 XML，特別值得一提的是連 Sun 的 JAXM 也在用 DOM4J。
Java代碼
複製代碼代碼如下:
package com.alisoft.facepay.framework.bean;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;
import java.util.Iterator;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;
/**
*
* @author hongliang.dinghl
* Dom4j 生成XML文檔與解析XML文檔
*/
public class Dom4jDemo implements XmlDocument {
public void createXml(String fileName) {
Document document = DocumentHelper.createDocument();
Element employees=document.addElement("employees");
Element employee=employees.addElement("employee");
Element name= employee.addElement("name");
name.setText("ddvip");
Element sex=employee.addElement("sex");
sex.setText("m");
Element age=employee.addElement("age");
age.setText("29");
try {
Writer fileWriter=new FileWriter(fileName);
XMLWriter xmlWriter=new XMLWriter(fileWriter);
xmlWriter.write(document);
xmlWriter.close();
} catch (IOException e) {
System.out.println(e.getMessage());
}
}
public void parserXml(String fileName) {
File inputXml=new File(fileName);
SAXReader saxReader = new SAXReader();
try {
Document document = saxReader.read(inputXml);
Element employees=document.getRootElement();
for(Iterator i = employees.elementIterator(); i.hasNext();){
Element employee = (Element) i.next();
for(Iterator j = employee.elementIterator(); j.hasNext();){
Element node=(Element) j.next();
System.out.println(node.getName()+":"+node.getText());
}
}
} catch (DocumentException e) {
System.out.println(e.getMessage());
}
System.out.println("dom4j parserXml");
}
}
4.JDOM生成和解析XML
爲減少DOM、SAX的編碼量，出現了JDOM；優點：20-80原則，極大減少了代碼量。使用場合：要實現的功能簡單，如解析、創建等，但在底層，JDOM還是使用SAX（最常用）、DOM、Xanan文檔。
複製代碼代碼如下:
package com.alisoft.facepay.framework.bean;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.List;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;
import org.jdom.output.XMLOutputter;
/**
*
* @author hongliang.dinghl
* JDOM 生成與解析XML文檔
*
*/
public class JDomDemo implements XmlDocument {
public void createXml(String fileName) {
Document document;
Element root;
root=new Element("employees");
document=new Document(root);
Element employee=new Element("employee");
root.addContent(employee);
Element name=new Element("name");
name.setText("ddvip");
employee.addContent(name);
Element sex=new Element("sex");
sex.setText("m");
employee.addContent(sex);
Element age=new Element("age");
age.setText("23");
employee.addContent(age);
XMLOutputter XMLOut = new XMLOutputter();
try {
XMLOut.output(document, new FileOutputStream(fileName));
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
public void parserXml(String fileName) {
SAXBuilder builder=new SAXBuilder(false);
try {
Document document=builder.build(fileName);
Element employees=document.getRootElement();
List employeeList=employees.getChildren("employee");
for(int i=0;iElement employee=(Element)employeeList.get(i);
List employeeInfo=employee.getChildren();
for(int j=0;jSystem.out.println(((Element)employeeInfo.get(j)).getName()+":"+((Element)employeeInfo.get(j)).getValue());
}
}
} catch (JDOMException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}