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dom4j学习笔记

摘要: dom4j学习笔记

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一、生成xml文件
1. 下载dom4j-1.6.1.jar和jaxen-1.1-beta-10.jar，下载地址分别如下：
http://www.dom4j.org/
http://jaxen.codehaus.org/releases.html

注：本文附带的源码中有以上两个JAR文件。

2. 写一个批处理文件dom4j.bat，内容如下：

set CLASSPATH=c:\test\jar\jaxen-1.1-beta-10.jar;c:\test\jar\dom4j-1.6.1.jar;%CLASSPATH%

3. 编写代码(编译前运行一下dom4j.bat),成功运行后会在cmd内显示生成的xml文件的内容，而且在C盘下会生成“output.xml”文件。大部分代码摘自官方网站的quick start，我做了些修正，因为官方的不能直接运行。代码如下：

import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;
import java.io.IOException;
import java.io.FileWriter;

public class CreateXML {

// 输出XML数据
public void write(Document document) throws IOException {

// xml 标准格式，保存到文件
OutputFormat format = OutputFormat.createPrettyPrint();
XMLWriter writer = new XMLWriter(new FileWriter( "c:\\output.xml" ), format );
writer.write( document );
writer.close();

// 紧凑的格式，System.out显示(
format = OutputFormat.createCompactFormat();
writer = new XMLWriter( System.out, format );
System.out.println("\r\n------------------Start------------------");
writer.write( document );
System.out.println("\r\n-------------------End-------------------");
writer.close();

}

// 返回XML对象
public Document createDocument() {
Document document = DocumentHelper.createDocument();
Element root = document.addElement( "root" );

Element author1 = root.addElement( "author" )
.addAttribute( "name", "James" )
.addAttribute( "location", "UK" )
.addText( "James Strachan" );

Element author2 = root.addElement( "author" )
.addAttribute( "name", "Bob" )
.addAttribute( "location", "US" )
.addText( "Bob McWhirter" );

return document;
}

public static void main(String[] args) {
CreateXML dom4j = new CreateXML();
try {
dom4j.write(dom4j.createDocument());

} catch (IOException e) {
System.out.println(e.getMessage());
}
}
}

4. 运行过程和结果：

C:\test>dom4j.bat

C:\test>set CLASSPATH=c:\test\jar\jaxen-1.1-beta-10.jar;c:\test\jar\dom4j-1.6.1.
jar;.;c:\jdk1.5\lib

C:\test>javac CreateXML.java

C:\test>java CreateXML

------------------Start------------------
<?xml version="1.0" encoding="UTF-8"?>
James StrachanBob McWhirter
-------------------End-------------------

C:\test>

二、获取XML文件中的数据

代码如下：

import java.net.URL;
import java.io.IOException;
import java.io.FileWriter;
import java.io.File;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.io.SAXReader;

public class Parse_1 {

public Document parse(String sfile) throws DocumentException {
SAXReader reader = new SAXReader();
Document document = reader.read(new File(sfile));
return document;
}

public void write(Document document) throws IOException {

// xml的格式，System.out显示(
OutputFormat format = OutputFormat.createPrettyPrint();
XMLWriter writer = new XMLWriter( System.out, format );
System.out.println("\r\n------------------Start------------------");
writer.write( document );
System.out.println("\r\n-------------------End-------------------");
}

public static void main(String[] args) {
Parse_1 dom4j = new Parse_1();
try {
dom4j.write(dom4j.parse("c:\\output.xml"));

} catch (IOException e) {
System.out.println(e.getMessage());
} catch (DocumentException e) {
System.out.println(e.getMessage());
}
}
}

运行过程和结果：

C:\test>dom4j

C:\test>set CLASSPATH=c:\test\jar\jaxen-1.1-beta-10.jar;c:\test\jar\dom4j-1.6.1.
jar;.;c:\jdk1.5\lib

C:\test>javac Parse_1.java

C:\test>java Parse_1

------------------Start------------------
<?xml version="1.0" encoding="UTF-8"?>

James Strachan
Bob McWhirter

-------------------End-------------------

C:\test>

三、获取、修改XML元素

代码如下：

import java.io.IOException;
import java.io.File;
import java.util.Iterator;
import java.util.List;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;
import org.dom4j.io.SAXReader;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Node;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.Attribute;

public class Parse_2 {

public Document parse(String sfile) throws DocumentException {
SAXReader reader = new SAXReader();
Document document = reader.read(new File(sfile));
return document;
}

public void bar(Document document) throws IOException {

List list = document.selectNodes( "//author" );
Iterator iter=list.iterator();

System.out.println("\r\n****** 获取的数据如下 ******");
while(iter.hasNext()){
Element titleElement=(Element)iter.next();
// 修改xml元素
if(titleElement.getText().equals("James Strachan")) {
titleElement.setText("Faint Heipark");
}
System.out.print(titleElement.valueOf( "@name" ) + "：");
System.out.println(titleElement.getText());
}

// 输出全部原始数据
OutputFormat format = OutputFormat.createPrettyPrint();
XMLWriter writer = new XMLWriter( System.out, format );
System.out.println("\r\n------------------Start------------------");
writer.write( document );
System.out.println("\r\n-------------------End-------------------");
}

public static void main(String[] args) {
Parse_2 dom4j = new Parse_2();
try {
dom4j.bar(dom4j.parse("c:\\output.xml"));

} catch (Exception e) {
System.out.println(e.getMessage());
}
}
}

运行结果：

C:\test>java Parse_2

****** 获取的数据如下 ******
James：Faint Heipark
Bob：Bob McWhirter

------------------Start------------------
<?xml version="1.0" encoding="UTF-8"?>

Faint Heipark
Bob McWhirter

-------------------End-------------------

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