[转]详解Java解析XML的四种方法
XML现在已经成为一种通用的数据交换格式,它的平台无关性,语言无关性,系统无关性,给数据集成与交互带来了极大的方便。对于XML本身的语法知识与技术细节,需要阅读相关的技术文献,这里面包括的内容有DOM(Document Object Model),DTD(Document Type Definition),SAX(Simple API for XML),XSD(Xml Schema Definition),XSLT(Extensible Stylesheet Language Transformations),具体可参阅w3c官方网站文档http://www.w3.org获取更多信息。
XML在不同的语言里解析方式都是一样的,只不过实现的语法不同而已。基本的解析方式有两种,一种叫SAX，另一种叫DOM。SAX是基于事件流的解析,DOM是基于XML文档树结构的解析。假设我们XML的内容和结构如下:
1 <?xml version="1.0" encoding="UTF-8"?>
2 <employees>
3 <employee>
4 <name>ddviplinux</name>
5 <sex>m</sex>
6 <age>30</age>
7 </employee>
8 </employees>
本文使用JAVA语言来实现DOM与SAX的XML文档生成与解析。
首先定义一个操作XML文档的接口XmlDocument 它定义了XML文档的建立与解析的接口。
package com.alisoft.facepay.framework.bean; /** * * @author hongliang.dinghl * 定义XML文档建立与解析的接口 */ public interface XmlDocument { /** * 建立XML文档 * @param fileName 文件全路径名称 */ public void createXml(String fileName); /** * 解析XML文档 * @param fileName 文件全路径名称 */ public void parserXml(String fileName); }
1.DOM生成和解析XML文档
为 XML 文档的已解析版本定义了一组接口。解析器读入整个文档，然后构建一个驻留内存的树结构，然后代码就可以使用 DOM 接口来操作这个树结构。优点：整个文档树在内存中，便于操作；支持删除、修改、重新排列等多种功能；缺点：将整个文档调入内存（包括无用的节点），浪费时间和空间；使用场合：一旦解析了文档还需多次访问这些数据；硬件资源充足（内存、CPU）。
1 package com.alisoft.facepay.framework.bean;
2 import java.io.FileInputStream;
3 import java.io.FileNotFoundException;
4 import java.io.FileOutputStream;
5 import java.io.IOException;
6 import java.io.InputStream;
7 import java.io.PrintWriter;
8 import javax.xml.parsers.DocumentBuilder;
9 import javax.xml.parsers.DocumentBuilderFactory;
10 import javax.xml.parsers.ParserConfigurationException;
11 import javax.xml.transform.OutputKeys;
12 import javax.xml.transform.Transformer;
13 import javax.xml.transform.TransformerConfigurationException;
14 import javax.xml.transform.TransformerException;
15 import javax.xml.transform.TransformerFactory;
16 import javax.xml.transform.dom.DOMSource;
17 import javax.xml.transform.stream.StreamResult;
18 import org.w3c.dom.Document;
19 import org.w3c.dom.Element;
20 import org.w3c.dom.Node;
21 import org.w3c.dom.NodeList;
22 import org.xml.sax.SAXException;
23 /**
24 *
25 * @author hongliang.dinghl
26 * DOM生成与解析XML文档
27 */
28 public class DomDemo implements XmlDocument {
29 private Document document;
30 private String fileName;
31 public void init() {
32 try {
33 DocumentBuilderFactory factory = DocumentBuilderFactory
34 .newInstance();
35 DocumentBuilder builder = factory.newDocumentBuilder();
36 this.document = builder.newDocument();
37 } catch (ParserConfigurationException e) {
38 System.out.println(e.getMessage());
39 }
40 }
41 public void createXml(String fileName) {
42 Element root = this.document.createElement("employees");
43 this.document.appendChild(root);
44 Element employee = this.document.createElement("employee");
45 Element name = this.document.createElement("name");
46 name.appendChild(this.document.createTextNode("丁宏亮"));
47 employee.appendChild(name);
48 Element sex = this.document.createElement("sex");
49 sex.appendChild(this.document.createTextNode("m"));
50 employee.appendChild(sex);
51 Element age = this.document.createElement("age");
52 age.appendChild(this.document.createTextNode("30"));
53 employee.appendChild(age);
54 root.appendChild(employee);
55 TransformerFactory tf = TransformerFactory.newInstance();
56 try {
57 Transformer transformer = tf.newTransformer();
58 DOMSource source = new DOMSource(document);
59 transformer.setOutputProperty(OutputKeys.ENCODING, "gb2312");
60 transformer.setOutputProperty(OutputKeys.INDENT, "yes");
61 PrintWriter pw = new PrintWriter(new FileOutputStream(fileName));
62 StreamResult result = new StreamResult(pw);
63 transformer.transform(source, result);
64 System.out.println("生成XML文件成功!");
65 } catch (TransformerConfigurationException e) {
66 System.out.println(e.getMessage());
67 } catch (IllegalArgumentException e) {
68 System.out.println(e.getMessage());
69 } catch (FileNotFoundException e) {
70 System.out.println(e.getMessage());
71 } catch (TransformerException e) {
72 System.out.println(e.getMessage());
73 }
74 }
75 public void parserXml(String fileName) {
76 try {
77 DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
78 DocumentBuilder db = dbf.newDocumentBuilder();
79 Document document = db.parse(fileName);
80 NodeList employees = document.getChildNodes();
81 for (int i = 0; i < employees.getLength(); i++) {
82 Node employee = employees.item(i);
83 NodeList employeeInfo = employee.getChildNodes();
84 for (int j = 0; j < employeeInfo.getLength(); j++) {
85 Node node = employeeInfo.item(j);
86 NodeList employeeMeta = node.getChildNodes();
87 for (int k = 0; k < employeeMeta.getLength(); k++) {
88 System.out.println(employeeMeta.item(k).getNodeName()
89 + ":" + employeeMeta.item(k).getTextContent());
90 }
91 }
92 }
93 System.out.println("解析完毕");
94 } catch (FileNotFoundException e) {
95 System.out.println(e.getMessage());
96 } catch (ParserConfigurationException e) {
97 System.out.println(e.getMessage());
98 } catch (SAXException e) {
99 System.out.println(e.getMessage());
100 } catch (IOException e) {
101 System.out.println(e.getMessage());
102 }
103 }
104 }
2.SAX生成和解析XML文档
为解决DOM的问题，出现了SAX。SAX ，事件驱动。当解析器发现元素开始、元素结束、文本、文档的开始或结束等时，发送事件，程序员编写响应这些事件的代码，保存数据。优点：不用事先调入整个文档，占用资源少；SAX解析器代码比DOM解析器代码小，适于Applet，下载。缺点：不是持久的；事件过后，若没保存数据，那么数据就丢了；无状态性；从事件中只能得到文本，但不知该文本属于哪个元素；使用场合：Applet;只需XML文档的少量内容，很少回头访问；机器内存少；
Java代码
1 package com.alisoft.facepay.framework.bean;
2 import java.io.FileInputStream;
3 import java.io.FileNotFoundException;
4 import java.io.IOException;
5 import java.io.InputStream;
6
7 import javax.xml.parsers.ParserConfigurationException;
8 import javax.xml.parsers.SAXParser;
9 import javax.xml.parsers.SAXParserFactory;
10
11 import org.xml.sax.Attributes;
12 import org.xml.sax.SAXException;
13 import org.xml.sax.helpers.DefaultHandler;
14 /**
15 *
16 * @author hongliang.dinghl
17 * SAX文档解析
18 */
19 public class SaxDemo implements XmlDocument {
20
21 public void createXml(String fileName) {
22 System.out.println("<<"+filename+">>");
23 }
24
25 public void parserXml(String fileName) {
26 SAXParserFactory saxfac = SAXParserFactory.newInstance();
27
28 try {
29
30 SAXParser saxparser = saxfac.newSAXParser();
31
32 InputStream is = new FileInputStream(fileName);
33
34 saxparser.parse(is, new MySAXHandler());
35
36 } catch (ParserConfigurationException e) {
37
38 e.printStackTrace();
39
40 } catch (SAXException e) {
41
42 e.printStackTrace();
43
44 } catch (FileNotFoundException e) {
45
46 e.printStackTrace();
47
48 } catch (IOException e) {
49
50 e.printStackTrace();
51
52 }
53
54 }
55
56 }
57
58 class MySAXHandler extends DefaultHandler {
59
60 boolean hasAttribute = false;
61
62 Attributes attributes = null;
63
64 public void startDocument() throws SAXException {
65
66 System.out.println("文档开始打印了");
67
68 }
69
70 public void endDocument() throws SAXException {
71
72 System.out.println("文档打印结束了");
73
74 }
75
76 public void startElement(String uri, String localName, String qName,
77
78 Attributes attributes) throws SAXException {
79
80 if (qName.equals("employees")) {
81
82 return;
83
84 }
85
86 if (qName.equals("employee")) {
87
88 System.out.println(qName);
89
90 }
91
92 if (attributes.getLength() > 0) {
93
94 this.attributes = attributes;
95
96 this.hasAttribute = true;
97
98 }
99
100 }
101
102 public void endElement(String uri, String localName, String qName)
103
104 throws SAXException {
105
106 if (hasAttribute && (attributes != null)) {
107
108 for (int i = 0; i < attributes.getLength(); i++) {
109
110 System.out.println(attributes.getQName(0)
111 + attributes.getValue(0));
112
113 }
114
115 }
116
117 }
118
119 public void characters(char[] ch, int start, int length)
120
121 throws SAXException {
122
123 System.out.println(new String(ch, start, length));
124
125 }
126
127 }
128 package com.alisoft.facepay.framework.bean;
129 import java.io.FileInputStream;
130 import java.io.FileNotFoundException;
131 import java.io.IOException;
132 import java.io.InputStream;
133 import javax.xml.parsers.ParserConfigurationException;
134 import javax.xml.parsers.SAXParser;
135 import javax.xml.parsers.SAXParserFactory;
136 import org.xml.sax.Attributes;
137 import org.xml.sax.SAXException;
138 import org.xml.sax.helpers.DefaultHandler;
139 /**
140 *
141 * @author hongliang.dinghl
142 * SAX文档解析
143 */
144 public class SaxDemo implements XmlDocument {
145 public void createXml(String fileName) {
146 System.out.println("<<"+filename+">>");
147 }
148 public void parserXml(String fileName) {
149 SAXParserFactory saxfac = SAXParserFactory.newInstance();
150 try {
151 SAXParser saxparser = saxfac.newSAXParser();
152 InputStream is = new FileInputStream(fileName);
153 saxparser.parse(is, new MySAXHandler());
154 } catch (ParserConfigurationException e) {
155 e.printStackTrace();
156 } catch (SAXException e) {
157 e.printStackTrace();
158 } catch (FileNotFoundException e) {
159 e.printStackTrace();
160 } catch (IOException e) {
161 e.printStackTrace();
162 }
163 }
164 }
165 class MySAXHandler extends DefaultHandler {
166 boolean hasAttribute = false;
167 Attributes attributes = null;
168 public void startDocument() throws SAXException {
169 System.out.println("文档开始打印了");
170 }
171 public void endDocument() throws SAXException {
172 System.out.println("文档打印结束了");
173 }
174 public void startElement(String uri, String localName, String qName,
175 Attributes attributes) throws SAXException {
176 if (qName.equals("employees")) {
177 return;
178 }
179 if (qName.equals("employee")) {
180 System.out.println(qName);
181 }
182 if (attributes.getLength() > 0) {
183 this.attributes = attributes;
184 this.hasAttribute = true;
185 }
186 }
187 public void endElement(String uri, String localName, String qName)
188 throws SAXException {
189 if (hasAttribute && (attributes != null)) {
190 for (int i = 0; i < attributes.getLength(); i++) {
191 System.out.println(attributes.getQName(0)
192 + attributes.getValue(0));
193 }
194 }
195 }
196 public void characters(char[] ch, int start, int length)
197 throws SAXException {
198 System.out.println(new String(ch, start, length));
199 }
200 }
3.DOM4J生成和解析XML文档
DOM4J 是一个非常非常优秀的Java XML API，具有性能优异、功能强大和极端易用使用的特点，同时它也是一个开放源代码的软件。如今你可以看到越来越多的 Java 软件都在使用 DOM4J 来读写 XML，特别值得一提的是连 Sun 的 JAXM 也在用 DOM4J。
Java代码
1 package com.alisoft.facepay.framework.bean;
2 import java.io.File;
3 import java.io.FileWriter;
4 import java.io.IOException;
5 import java.io.Writer;
6 import java.util.Iterator;
7
8 import org.dom4j.Document;
9 import org.dom4j.DocumentException;
10 import org.dom4j.DocumentHelper;
11 import org.dom4j.Element;
12 import org.dom4j.io.SAXReader;
13 import org.dom4j.io.XMLWriter;
14 /**
15 *
16 * @author hongliang.dinghl
17 * Dom4j 生成XML文档与解析XML文档
18 */
19 public class Dom4jDemo implements XmlDocument {
20
21 public void createXml(String fileName) {
22 Document document = DocumentHelper.createDocument();
23 Element employees=document.addElement("employees");
24 Element employee=employees.addElement("employee");
25 Element name= employee.addElement("name");
26 name.setText("ddvip");
27 Element sex=employee.addElement("sex");
28 sex.setText("m");
29 Element age=employee.addElement("age");
30 age.setText("29");
31 try {
32 Writer fileWriter=new FileWriter(fileName);
33 XMLWriter xmlWriter=new XMLWriter(fileWriter);
34 xmlWriter.write(document);
35 xmlWriter.close();
36 } catch (IOException e) {
37
38 System.out.println(e.getMessage());
39 }
40
41
42 }
43
44
45 public void parserXml(String fileName) {
46 File inputXml=new File(fileName);
47 SAXReader saxReader = new SAXReader();
48 try {
49 Document document = saxReader.read(inputXml);
50 Element employees=document.getRootElement();
51 for(Iterator i = employees.elementIterator(); i.hasNext();){
52 Element employee = (Element) i.next();
53 for(Iterator j = employee.elementIterator(); j.hasNext();){
54 Element node=(Element) j.next();
55 System.out.println(node.getName()+":"+node.getText());
56 }
57
58 }
59 } catch (DocumentException e) {
60 System.out.println(e.getMessage());
61 }
62 System.out.println("dom4j parserXml");
63 }
64 }
4.JDOM生成和解析XML
为减少DOM、SAX的编码量，出现了JDOM；优点：20-80原则，极大减少了代码量。使用场合：要实现的功能简单，如解析、创建等，但在底层，JDOM还是使用SAX（最常用）、DOM、Xanan文档。
1 package com.alisoft.facepay.framework.bean;
2
3 import java.io.FileNotFoundException;
4 import java.io.FileOutputStream;
5 import java.io.IOException;
6 import java.util.List;
7
8 import org.jdom.Document;
9 import org.jdom.Element;
10 import org.jdom.JDOMException;
11 import org.jdom.input.SAXBuilder;
12 import org.jdom.output.XMLOutputter;
13 /**
14 *
15 * @author hongliang.dinghl
16 * JDOM 生成与解析XML文档
17 *
18 */
19 public class JDomDemo implements XmlDocument {
20
21 public void createXml(String fileName) {
22 Document document;
23 Element root;
24 root=new Element("employees");
25 document=new Document(root);
26 Element employee=new Element("employee");
27 root.addContent(employee);
28 Element name=new Element("name");
29 name.setText("ddvip");
30 employee.addContent(name);
31 Element sex=new Element("sex");
32 sex.setText("m");
33 employee.addContent(sex);
34 Element age=new Element("age");
35 age.setText("23");
36 employee.addContent(age);
37 XMLOutputter XMLOut = new XMLOutputter();
38 try {
39 XMLOut.output(document, new FileOutputStream(fileName));
40 } catch (FileNotFoundException e) {
41 e.printStackTrace();
42 } catch (IOException e) {
43 e.printStackTrace();
44 }
45
46 }
47
48 public void parserXml(String fileName) {
49 SAXBuilder builder=new SAXBuilder(false);
50 try {
51 Document document=builder.build(fileName);
52 Element employees=document.getRootElement();
53 List employeeList=employees.getChildren("employee");
54 for(int i=0;iElement employee=(Element)employeeList.get(i);
55 List employeeInfo=employee.getChildren();
56 for(int j=0;jSystem.out.println(((Element)employeeInfo.get(j)).getName()+":"+((Element)employeeInfo.get(j)).getValue());
57
58 }
59 }
60 } catch (JDOMException e) {
61
62 e.printStackTrace();
63 } catch (IOException e) {
64
65 e.printStackTrace();
66 }
67
68 }
69 }
70
原文链接：http://developer.51cto.com/art/200903/117512.htm
