雖然Java中已經有了Dom和Sax這兩種標準解析方式
但其操作起來并不輕松，對于我這么一個初學者來說，其中部分代碼是活生生的惡心
為此，偉大的第三方開發組開發出了Jdom和Dom4j等工具
鑒于目前的趨勢，我們這里來講講Dom4j的基本用法，不涉及遞歸等復雜操作
Dom4j的用法很多，官網上的示例有那么點兒晦澀，這里就不寫了
首先我們需要出創建一個xml文檔，然后才能對其解析
xml文檔：
<?xml version="1.0" encoding="UTF-8"?>
<books>
<book id="001">
<title>Harry Potter</title>
<author>J K. Rowling</author>
</book>
<book id="002">
<title>Learning XML</title>
<author>Erik T. Ray</author>
</book>
</books>
示例一：用List列表的方式來解析xml
import java.io.File;
import java.util.List;
import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
public class Demo {
public static void main(String[] args) throws Exception {
SAXReader reader = new SAXReader();
File file = new File("books.xml");
Document document = reader.read(file);
Element root = document.getRootElement();
List<Element> childElements = root.elements();
for (Element child : childElements) {
//未知屬性名情況下
/*List<Attribute> attributeList = child.attributes();
for (Attribute attr : attributeList) {
System.out.println(attr.getName() + ": " + attr.getValue());
}*/
//已知屬性名情況下
System.out.println("id: " + child.attributeValue("id"));
//未知子元素名情況下
/*List<Element> elementList = child.elements();
for (Element ele : elementList) {
System.out.println(ele.getName() + ": " + ele.getText());
}
System.out.println();*/
//已知子元素名的情況下
System.out.println("title" + child.elementText("title"));
System.out.println("author" + child.elementText("author"));
//這行是為了格式化美觀而存在
System.out.println();
}
}
}
示例二：使用Iterator迭代器的方式來解析xml
import java.io.File;
import java.util.Iterator;
import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
public class Demo {
public static void main(String[] args) throws Exception {
SAXReader reader = new SAXReader();
Document document = reader.read(new File("books.xml"));
Element root = document.getRootElement();
Iterator it = root.elementIterator();
while (it.hasNext()) {
Element element = (Element) it.next();
//未知屬性名稱情況下
/*Iterator attrIt = element.attributeIterator();
while (attrIt.hasNext()) {
Attribute a = (Attribute) attrIt.next();
System.out.println(a.getValue());
}*/
//已知屬性名稱情況下
System.out.println("id: " + element.attributeValue("id"));
//未知元素名情況下
/*Iterator eleIt = element.elementIterator();
while (eleIt.hasNext()) {
Element e = (Element) eleIt.next();
System.out.println(e.getName() + ": " + e.getText());
}
System.out.println();*/
//已知元素名情況下
System.out.println("title: " + element.elementText("title"));
System.out.println("author: " + element.elementText("author"));
System.out.println();
}
}
}
運行結果：
示例三：創建xml文檔并輸出到文件
import java.io.File;
import java.io.FileOutputStream;
import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;
public class Demo {
public static void main(String[] args) throws Exception {
Document doc = DocumentHelper.createDocument();
//增加根節點
Element books = doc.addElement("books");
//增加子元素
Element book1 = books.addElement("book");
Element title1 = book1.addElement("title");
Element author1 = book1.addElement("author");
Element book2 = books.addElement("book");
Element title2 = book2.addElement("title");
Element author2 = book2.addElement("author");
//為子節點添加屬性
book1.addAttribute("id", "001");
//為元素添加內容
title1.setText("Harry Potter");
author1.setText("J K. Rowling");
book2.addAttribute("id", "002");
title2.setText("Learning XML");
author2.setText("Erik T. Ray");
//實例化輸出格式對象
OutputFormat format = OutputFormat.createPrettyPrint();
//設置輸出編碼
format.setEncoding("UTF-8");
//創建需要寫入的File對象
File file = new File("D:" + File.separator + "books.xml");
//生成XMLWriter對象，構造函數中的參數為需要輸出的文件流和格式
XMLWriter writer = new XMLWriter(new FileOutputStream(file), format);
//開始寫入，write方法中包含上面創建的Document對象
writer.write(doc);
}
}
運行結果：
