使用Dom4j操作XML
Dom4j也可以很方便完成XML文档的创建、元素的修改、文档的查询遍历等，但dom4j稍比jdom复杂一点，不过在大片文档的情况下dom4j的性能要不jdom好。
# 准备
首先，提供相关的jar包
Dom4j jar包下载：
http://sourceforge.net/projects/dom4j/files/dom4j-2.0.0-ALPHA-2/
jaxen jar下载：
http://repo1.maven.org/maven2/jaxen/jaxen/1.1.1/jaxen-1.1.1.jar
和dom4j依赖或相关的jar：
http://dom4j.sourceforge.net/dependencies.html
Junit-jar下载：
http://ebr.springsource.com/repository/app/bundle/version/download?name=com.springsource.org.junit&version=4.8.1&type=binary
其次，准备测试案例的部分代码：
1 package com.hoo.test; 2
3 import java.io.File; 4 import java.util.Iterator; 5 import java.util.List; 6 import org.dom4j.Attribute; 7 import org.dom4j.Document; 8 import org.dom4j.DocumentException; 9 import org.dom4j.DocumentHelper; 10 import org.dom4j.Element; 11 import org.dom4j.Node; 12 import org.dom4j.QName; 13 import org.dom4j.dom.DOMAttribute; 14 import org.dom4j.io.SAXReader; 15 import org.dom4j.tree.BaseElement; 16 import org.junit.After; 17 import org.junit.Before; 18 import org.junit.Test; 19
20 /**
21 * <b>function:</b> 使用Dom4j操作XML 22 * @author hoojo 23 * @createDate 2011-8-5 下午06:15:40 24 * @file DocumentTest.java 25 * @package com.hoo.test 26 * @project Dom4jTest 27 * @blog http://blog.csdn.net/IBM_hoojo
28 * @email [email protected] 29 * @version 1.0 30 */
31 public class DocumentTest { 32
33 private SAXReader reader = null; 34
35 @Before 36 public void init() { 37 reader = new SAXReader(); 38 } 39
40 @After 41 public void destory() { 42 reader = null; 43 System.gc(); 44 } 45
46 public void fail(Object o) { 47 if (o != null) 48 System.out.println(o); 49 } 50 }
# 创建一篇XML文档
文档格式如下：
1 <?xml version="1.0" encoding="UTF-8"?>
2 <catalog>
3 <!--An XML Catalog-->
4 <?target instruction?>
5 <journal title="XML Zone" publisher="IBM developerWorks">
6 <article level="Intermediate" date="December-2001">
7 <title>Java configuration with XML Schema</title>
8 <author>
9 <firstname>Marcello</firstname>
10 <lastname>Vitaletti</lastname>
11 </author>
12 </article>
13 </journal>
14 </catalog>
创建文档代码如下：
1 /**
2 * <b>function:</b>创建文档 3 * @author hoojo 4 * @createDate 2011-8-5 下午06:18:18 5 */
6 @Test 7 public void createDocument() { 8 //创建一篇文档
9 Document doc = DocumentHelper.createDocument(); 10
11 //添加一个元素
12 Element root = doc.addElement("catalog"); 13 //为root元素添加注释
14 root.addComment("An XML Catalog"); 15 //添加标记
16 root.addProcessingInstruction("target", "instruction"); 17
18 //创建元素
19 Element journalEl = new BaseElement("journal"); 20 //添加属性
21 journalEl.addAttribute("title", "XML Zone"); 22 journalEl.addAttribute("publisher", "IBM developerWorks"); 23 root.add(journalEl); 24
25 //添加元素
26 Element articleEl = journalEl.addElement("article"); 27 articleEl.addAttribute("level", "Intermediate"); 28 articleEl.addAttribute("date", "December-2001"); 29
30 Element titleEl = articleEl.addElement("title"); 31 //设置文本内容
32 titleEl.setText("Java configuration with XML Schema"); 33 //titleEl.addText("Java configuration with XML Schema");
34
35 Element authorEl = articleEl.addElement("author"); 36 authorEl.addElement("firstname").setText("Marcello"); 37 authorEl.addElement("lastname").addText("Vitaletti"); 38
39 //可以使用 addDocType() 方法添加文档类型说明。
40 doc.addDocType("catalog", null,"file://c:/Dtds/catalog.dtd"); 41
42 fail(doc.getRootElement().getName()); 43
44 //将xml转换成文本
45 fail(doc.asXML()); 46
47 //写入到文件
48 /*XMLWriter output; 49 try { 50 output = new XMLWriter(new FileWriter(new File("file/catalog.xml"))); 51 output.write(doc); 52 output.close(); 53 } catch (IOException e) { 54 e.printStackTrace(); 55 }*/
56 }
* DocumentHelper是一个文档助手类（工具类），它可以完成文档、元素、文本、属性、注释、CDATA、Namespace、XPath的创建，以及利用XPath完成文档的遍历和将文本转换成Document；
parseText完成将xml字符串转换成Doc的功能
Document doc = DocumentHelper.parseText("<root></root>");
createDocument创建一个文档
Document doc = DocumentHelper.createDocument();
如果带参数就会创建一个带有根元素的文档
createElement创建一个元素
Element el = DocumentHelper.createElement("el");
* Document的addElement方法可以给当前文档添加一个子元素
Element root = doc.addElement("catalog");
* addComment方法可以添加一段注释
root.addComment("An XML Catalog");
为root元素添加一段注释
* addProcessingInstruction添加一个标记
root.addProcessingInstruction("target", "instruction");
为root元素添加一个标记
* new BaseElement可以创建一个元素
Element journalEl = new BaseElement("journal");
* addAttribute添加属性
journalEl.addAttribute("title", "XML Zone");
* add添加一个元素
root.add(journalEl);
将journalEl元素添加到root元素中
* addElement添加一个元素，并返回当前元素
Element articleEl = journalEl.addElement("article");
给journalEl元素添加一个子元素article
* setText、addText可以设置元素的文本
authorEl.addElement("firstname").setText("Marcello");
authorEl.addElement("lastname").addText("Vitaletti");
* addDocType可以设置文档的DOCTYPE
doc.addDocType("catalog", null,file://c:/Dtds/catalog.dtd);
* asXML可以将文档或元素转换成一段xml字符串
doc.asXML();
root.asXML();
* XMLWriter类可以把文档写入到文件中
output = new XMLWriter(new FileWriter(new File("file/catalog.xml")));
output.write(doc);
output.close();
# 修改XML文档内容
1 /**
2 * <b>function:</b> 修改XML内容 3 * @author hoojo 4 * @createDate 2011-8-9 下午03:37:04 5 */
6 @SuppressWarnings("unchecked") 7 @Test 8 public void modifyDoc() { 9 try { 10 Document doc = reader.read(new File("file/catalog.xml")); 11
12 //修改属性内容
13 List list = doc.selectNodes("//article/@level"); 14 Iterator<Attribute> iter = list.iterator(); 15 while (iter.hasNext()) { 16 Attribute attr = iter.next(); 17 fail(attr.getName() + "#" + attr.getValue() + "#" + attr.getText()); 18 if ("Intermediate".equals(attr.getValue())) { 19 //修改属性值
20 attr.setValue("Introductory"); 21 fail(attr.getName() + "#" + attr.getValue() + "#" + attr.getText()); 22 } 23 } 24
25 list = doc.selectNodes("//article/@date"); 26 iter = list.iterator(); 27 while (iter.hasNext()) { 28 Attribute attr = iter.next(); 29 fail(attr.getName() + "#" + attr.getValue() + "#" + attr.getText()); 30 if ("December-2001".equals(attr.getValue())) { 31 //修改属性值
32 attr.setValue("December-2011"); 33 fail(attr.getName() + "#" + attr.getValue() + "#" + attr.getText()); 34 } 35 } 36
37 //修改节点内容
38 list = doc.selectNodes("//article"); 39 Iterator<Element> it = list.iterator(); 40 while (it.hasNext()) { 41 Element el = it.next(); 42 fail(el.getName() + "#" + el.getText() + "#" + el.getStringValue()); 43 //修改title元素
44 Iterator<Element> elIter = el.elementIterator("title"); 45 while(elIter.hasNext()) { 46 Element titleEl = elIter.next(); 47 fail(titleEl.getName() + "#" + titleEl.getText() + "#" + titleEl.getStringValue()); 48 if ("Java configuration with XML Schema".equals(titleEl.getTextTrim())) { 49 //修改元素文本值
50 titleEl.setText("Modify the Java configuration with XML Schema"); 51 fail(titleEl.getName() + "#" + titleEl.getText() + "#" + titleEl.getStringValue()); 52 } 53 } 54 } 55
56 //修改节点子元素内容
57 list = doc.selectNodes("//article/author"); 58 it = list.iterator(); 59 while (it.hasNext()) { 60 Element el = it.next(); 61 fail(el.getName() + "#" + el.getText() + "#" + el.getStringValue()); 62 List<Element> childs = el.elements(); 63 for (Element e : childs) { 64 fail(e.getName() + "#" + e.getText() + "#" + e.getStringValue()); 65 if ("Marcello".equals(e.getTextTrim())) { 66 e.setText("Ayesha"); 67 } else if ("Vitaletti".equals(e.getTextTrim())) { 68 e.setText("Malik"); 69 } 70 fail(e.getName() + "#" + e.getText() + "#" + e.getStringValue()); 71 } 72 } 73
74 //写入到文件
75 /*XMLWriter output = new XMLWriter(new FileWriter(new File("file/catalog-modified.xml"))); 76 output.write(doc); 77 output.close();*/
78 } catch (DocumentException e) { 79 e.printStackTrace(); 80 } catch (Exception e) { 81 e.printStackTrace(); 82 } 83 }
* reader.read(new File("file/catalog.xml"));读取指定xml文件内容到文档中；
* selectNodes是XPath的查询方法，完成xml文档的查询，传递xpath路径。其使用方法可以参考jdom的xpath的使用方法：
http://www.cnblogs.com/hoojo/archive/2011/08/11/2134638.html
* getName获取元素标签名称、getValue、getText获取值、文本内容；
* elementIterator("title");获取当前节点下所有的title元素，返回Iterator；
* elements获取下面所有的子元素，返回的是一个集合List；
# 显示文档相关信息
1 private String format(int i) { 2 String temp = ""; 3 while (i > 0) { 4 temp += "--"; 5 i--; 6 } 7 return temp; 8 } 9
10 /**
11 * <b>function:</b>递归显示文档内容 12 * @author hoojo 13 * @createDate 2011-8-9 下午03:43:45 14 * @param i 15 * @param els 16 */
17 private void print(int i, List<Element> els) { 18 i++; 19 for (Element el : els) { 20 fail(format(i) + "##" + el.getName() + "#" + el.getTextTrim()); 21 if (el.hasContent()) { 22 print(i, el.elements()); 23 } 24 } 25 } 26
27 /**
28 * <b>function:</b>显示文档相关信息 29 * @author hoojo 30 * @createDate 2011-8-9 下午03:44:10 31 */
32 @Test 33 public void printInfo() { 34 try { 35 Document doc = reader.read(new File("file/catalog.xml")); 36 fail("asXML: " + doc.asXML()); 37
38 fail(doc.asXPathResult(new BaseElement("article"))); 39 List<Node> list = doc.content(); 40 for (Node node : list) { 41 fail("Node: " + node.getName() + "#" + node.getText() + "#" + node.getStringValue()); 42 } 43
44 fail("-----------------------------"); 45 print(0, doc.getRootElement().elements()); 46
47 fail("getDocType: " + doc.getDocType()); 48 fail("getNodeTypeName: " + doc.getNodeTypeName()); 49 fail("getPath: " + doc.getRootElement().getPath()); 50 fail("getPath: " + doc.getRootElement().getPath(new BaseElement("journal"))); 51 fail("getUniquePath: " + doc.getRootElement().getUniquePath()); 52 fail("getXMLEncoding: " + doc.getXMLEncoding()); 53 fail("hasContent: " + doc.hasContent()); 54 fail("isReadOnly: " + doc.isReadOnly()); 55 fail("nodeCount: " + doc.nodeCount()); 56 fail("supportsParent: " + doc.supportsParent()); 57 } catch (DocumentException e) { 58 e.printStackTrace(); 59 } 60 fail("getEncoding: " + reader.getEncoding()); 61 fail("isIgnoreComments: " + reader.isIgnoreComments()); 62 fail("isMergeAdjacentText: " + reader.isMergeAdjacentText()); 63 fail("isStringInternEnabled: " + reader.isStringInternEnabled()); 64 fail("isStripWhitespaceText: " + reader.isStripWhitespaceText()); 65 fail("isValidating: " + reader.isValidating()); 66 }
# 删除文档内容
1 /**
2 * <b>function:</b> 删除节点内容 3 * @author hoojo 4 * @createDate 2011-8-9 下午03:47:44 5 */
6 @Test 7 public void removeNode() { 8 try { 9 Document doc = reader.read(new File("file/catalog-modified.xml")); 10 fail("comment: " + doc.selectSingleNode("//comment()")); 11 //删除注释
12 doc.getRootElement().remove(doc.selectSingleNode("//comment()")); 13
14 Element node = (Element) doc.selectSingleNode("//article"); 15 //删除属性
16 node.remove(new DOMAttribute(QName.get("level"), "Introductory")); 17 //删除元素 节点
18 node.remove(doc.selectSingleNode("//title")); 19
20 //只能删除下一级节点，不能超过一级；（需要在父元素的节点上删除子元素）
21 Node lastNameNode = node.selectSingleNode("//lastname"); 22 lastNameNode.getParent().remove(lastNameNode); 23
24 fail("Text: " + doc.selectObject("//*[text()='Ayesha']")); 25 Element firstNameEl = (Element)doc.selectObject("//firstname"); 26 fail("Text: " + firstNameEl.selectSingleNode("text()")); 27
28 //删除text文本 29 //firstNameEl.remove(firstNameEl.selectSingleNode("text()")); 30 //firstNameEl.remove(doc.selectSingleNode("//firstname/text()"));
31 firstNameEl.remove(doc.selectSingleNode("//*[text()='Ayesha']/text()")); 32
33 //删除子元素author 34 //node.remove(node.selectSingleNode("//author"));
35
36 fail(doc.asXML()); 37 } catch (Exception e) { 38 e.printStackTrace(); 39 } 40 }
* 删除注释
doc.getRootElement().remove(doc.selectSingleNode("//comment()"));
删除root元素下面的注释
* 删除属性
node.remove(new DOMAttribute(QName.get("level"), "Introductory"));
删除node节点中的名称为level，其值为Introductory的属性
* 删除元素
node.remove(doc.selectSingleNode("//title"));
删除node节点下的title元素
* 删除文本
firstNameEl.remove(firstNameEl.selectSingleNode("text()"));
firstNameEl.remove(doc.selectSingleNode("//firstname/text()"));
firstNameEl.remove(doc.selectSingleNode("//*[text()='Ayesha']/text()"));