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：
其次，准备测试案例的部分代码：
package
com.hoo.test;
import
java.io.File;
import
java.util.Iterator;
import
java.util.List;
import
org.dom4j.Attribute;
import
org.dom4j.Document;
import
org.dom4j.DocumentException;
import
org.dom4j.DocumentHelper;
import
org.dom4j.Element;
import
org.dom4j.Node;
import
org.dom4j.QName;
import
org.dom4j.dom.DOMAttribute;
import
org.dom4j.io.SAXReader;
import
org.dom4j.tree.BaseElement;
import
org.junit.After;
import
org.junit.Before;
import
org.junit.Test;
/**
* <b>function:</b> 使用Dom4j操作XML
* @author hoojo
* @createDate 2011-8-5 下午06:15:40
* @file DocumentTest.java
* @package com.hoo.test
* @project Dom4jTest
* @blog http://blog.csdn.net/IBM_hoojo
* @email [email protected]
* @version 1.0
*/
public class DocumentTest {
private
SAXReader reader = null;
@Before
public void init() {
reader = new
SAXReader();
}
@After
public void destory() {
reader = null;
System.gc();
}
public void fail(Object o) {
if
(o != null)
System.out.println(o);
}
}
# 创建一篇 XML 文档
文档格式如下：
<? xml version ="1.0" encoding ="UTF-8" ?>
< catalog >
<!--An XML Catalog-->
<? target instruction ?>
< journal title ="XML Zone" publisher ="IBM developerWorks" >
< article level ="Intermediate" date ="December-2001" >
< title > Java configuration with XML Schema</ title >
< author >
< firstname > Marcello</ firstname >
< lastname > Vitaletti</ lastname >
</ author >
</ article >
</ journal >
</ catalog >
创建文档代码如下：
/**
* <b>function:</b>创建文档
* @author hoojo
* @createDate 2011-8-5 下午06:18:18
*/
@Test
public void createDocument() {
//创建一篇文档
Document doc = DocumentHelper.createDocument();
//添加一个元素
Element root = doc.addElement("catalog"
);
//为root元素添加注释
root.addComment("An XML Catalog"
);
//添加标记
root.addProcessingInstruction("target" , "instruction" );
//创建元素
Element journalEl = new BaseElement("journal" );
//添加属性
journalEl.addAttribute("title" , "XML Zone" );
journalEl.addAttribute("publisher" , "IBM developerWorks" );
root.add(journalEl);
//添加元素
Element articleEl = journalEl.addElement("article"
);
articleEl.addAttribute("level" , "Intermediate" );
articleEl.addAttribute("date" , "December-2001" );
Element titleEl = articleEl.addElement("title"
);
//设置文本内容
titleEl.setText("Java configuration with XML Schema"
);
//titleEl.addText("Java configuration with XML Schema");
Element authorEl = articleEl.addElement("author"
);
authorEl.addElement("firstname" ).setText("Marcello" );
authorEl.addElement("lastname" ).addText("Vitaletti" );
//可以使用 addDocType() 方法添加文档类型说明。
doc.addDocType("catalog" , null,"file://c:/Dtds/catalog.dtd" );
fail(doc.getRootElement().getName());
//将xml转换成文本
fail(doc.asXML());
//写入到文件
/*XMLWriter output;
try {
output = new XMLWriter(new FileWriter(new File("file/catalog.xml")));
output.write(doc);
output.close();
} catch (IOException e) {
e.printStackTrace();
}*/
}
* 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
/**
* <b>function:</b> 修改XML内容
* @author hoojo
* @createDate 2011-8-9 下午03:37:04
*/
@SuppressWarnings("unchecked"
)
@Test
public void modifyDoc() {
try
{
Document doc = reader.read(new File("file/catalog.xml" ));
//修改属性内容
List list = doc.selectNodes("//article/@level"
);
Iterator<Attribute> iter = list.iterator();
while
(iter.hasNext()) {
Attribute attr = iter.next();
fail(attr.getName() + "#" + attr.getValue() + "#" + attr.getText());
if ("Intermediate" .equals(attr.getValue())) {
//修改属性值
attr.setValue("Introductory"
);
fail(attr.getName() + "#" + attr.getValue() + "#" + attr.getText());
}
}
list = doc.selectNodes("//article/@date"
);
iter = list.iterator();
while
(iter.hasNext()) {
Attribute attr = iter.next();
fail(attr.getName() + "#" + attr.getValue() + "#" + attr.getText());
if ("December-2001" .equals(attr.getValue())) {
//修改属性值
attr.setValue("December-2011"
);
fail(attr.getName() + "#" + attr.getValue() + "#" + attr.getText());
}
}
//修改节点内容
list = doc.selectNodes("//article"
);
Iterator<Element> it = list.iterator();
while
(it.hasNext()) {
Element el = it.next();
fail(el.getName() + "#" + el.getText() + "#" + el.getStringValue());
//修改title元素
Iterator<Element> elIter = el.elementIterator("title"
);
while
(elIter.hasNext()) {
Element titleEl = elIter.next();
fail(titleEl.getName() + "#" + titleEl.getText() + "#" + titleEl.getStringValue());
if ("Java configuration with XML Schema" .equals(titleEl.getTextTrim())) {
//修改元素文本值
titleEl.setText("Modify the Java configuration with XML Schema"
);
fail(titleEl.getName() + "#" + titleEl.getText() + "#" + titleEl.getStringValue());
}
}
}
//修改节点子元素内容
list = doc.selectNodes("//article/author"
);
it = list.iterator();
while
(it.hasNext()) {
Element el = it.next();
fail(el.getName() + "#" + el.getText() + "#" + el.getStringValue());
List<Element> childs = el.elements();
for
(Element e : childs) {
fail(e.getName() + "#" + e.getText() + "#" + e.getStringValue());
if ("Marcello" .equals(e.getTextTrim())) {
e.setText("Ayesha"
);
} else if ("Vitaletti" .equals(e.getTextTrim())) {
e.setText("Malik"
);
}
fail(e.getName() + "#" + e.getText() + "#" + e.getStringValue());
}
}
//写入到文件
/*XMLWriter output = new XMLWriter(new FileWriter(new File("file/catalog-modified.xml")));
output.write(doc);
output.close();*/
} catch
(DocumentException e) {
e.printStackTrace();
} catch
(Exception e) {
e.printStackTrace();
}
}
* 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
private String format(int i) {
String temp = ""
;
while
(i > 0) {
temp += "--"
;
i--;
}
return
temp;
}
/**
* <b>function:</b>递归显示文档内容
* @author hoojo
* @createDate 2011-8-9 下午03:43:45
* @param i
* @param els
*/
private void print(int i, List<Element> els) {
i++;
for
(Element el : els) {
fail(format(i) + "##" + el.getName() + "#" + el.getTextTrim());
if
(el.hasContent()) {
print(i, el.elements());
}
}
}
/**
* <b>function:</b>显示文档相关信息
* @author hoojo
* @createDate 2011-8-9 下午03:44:10
*/
@Test
public void printInfo() {
try
{
Document doc = reader.read(new File("file/catalog.xml" ));
fail("asXML: "
+ doc.asXML());
fail(doc.asXPathResult(new BaseElement("article" )));
List<Node> list = doc.content();
for
(Node node : list) {
fail("Node: " + node.getName() + "#" + node.getText() + "#" + node.getStringValue());
}
fail("-----------------------------"
);
print(0, doc.getRootElement().elements());
fail("getDocType: "
+ doc.getDocType());
fail("getNodeTypeName: "
+ doc.getNodeTypeName());
fail("getPath: "
+ doc.getRootElement().getPath());
fail("getPath: " + doc.getRootElement().getPath(new BaseElement("journal" )));
fail("getUniquePath: "
+ doc.getRootElement().getUniquePath());
fail("getXMLEncoding: "
+ doc.getXMLEncoding());
fail("hasContent: "
+ doc.hasContent());
fail("isReadOnly: "
+ doc.isReadOnly());
fail("nodeCount: "
+ doc.nodeCount());
fail("supportsParent: "
+ doc.supportsParent());
} catch
(DocumentException e) {
e.printStackTrace();
}
fail("getEncoding: "
+ reader.getEncoding());
fail("isIgnoreComments: "
+ reader.isIgnoreComments());
fail("isMergeAdjacentText: "
+ reader.isMergeAdjacentText());
fail("isStringInternEnabled: "
+ reader.isStringInternEnabled());
fail("isStripWhitespaceText: "
+ reader.isStripWhitespaceText());
fail("isValidating: "
+ reader.isValidating());
}
# 删除文档内容
/**
* <b>function:</b> 删除节点内容
* @author hoojo
* @createDate 2011-8-9 下午03:47:44
*/
@Test
public void removeNode() {
try
{
Document doc = reader.read(new File("file/catalog-modified.xml" ));
fail("comment: " + doc.selectSingleNode("//comment()" ));
//删除注释
doc.getRootElement().remove(doc.selectSingleNode("//comment()"
));
Element node = (Element) doc.selectSingleNode("//article"
);
//删除属性
node.remove(new DOMAttribute(QName.get("level" ), "Introductory" ));
//删除元素 节点
node.remove(doc.selectSingleNode("//title"
));
//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）
Node lastNameNode = node.selectSingleNode("//lastname"
);
lastNameNode.getParent().remove(lastNameNode);
fail("Text: " + doc.selectObject("//*[text()='Ayesha']" ));
Element firstNameEl = (Element)doc.selectObject("//firstname"
);
fail("Text: " + firstNameEl.selectSingleNode("text()" ));
//删除text文本
//firstNameEl.remove(firstNameEl.selectSingleNode("text()"));
//firstNameEl.remove(doc.selectSingleNode("//firstname/text()"));
firstNameEl.remove(doc.selectSingleNode("//*[text()='Ayesha']/text()"
));
//删除子元素author
//node.remove(node.selectSingleNode("//author"));
fail(doc.asXML());
} catch
(Exception e) {
e.printStackTrace();
}
}
* 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()" ));
删除firstNameEl的文本内容