xml-03-Java操作XML

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一、递归遍历整个文档

1.创建Document对象

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();// 创建文档构建器工厂

DocumentBuilder builder = factory.newDocumentBuilder(); // 通过工厂来获得文档构建器

Document doc = builder.parse(new File("example.xml")); //读取xml文件生成一个document对象

2.递归打印节点名称

public static void printNodeName(Node node,String line){

if(node instanceof Element){

System.out.println(line + node.getNodeName());

}

if(node.hasChildNodes()){

NodeList nl = node.getChildNodes();

for(int i =0;i<nl.getLength();i++){

printNodeName(nl.item(i),line+"\t");

}

3.完整事例

package xml;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;

import org.w3c.dom.Element;

import org.w3c.dom.Node;

import org.w3c.dom.NodeList;

public class ReadXml {

public static void main(String[] args) throws Exception {

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

DocumentBuilder builder = factory.newDocumentBuilder();

Document document = builder.parse(ReadXml.class.getClassLoader().getResourceAsStream("config.xml"));

Node nodeList = document.getFirstChild();

printNodeName(nodeList,"");

}

public static void printNodeName(Node node,String line){

if(node instanceof Element){

System.out.println(line + node.getNodeName());

}

if(node.hasChildNodes()){

NodeList nl = node.getChildNodes();

for(int i =0;i<nl.getLength();i++){

printNodeName(nl.item(i),line+"\t");

}

}

二、写Document到文档

1.创建Document对象

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

DocumentBuilder builder = factory.newDocumentBuilder();

Document doc = builder.newDocument(); // 创建一个新的对象

2.创建Dom节点

Element rootEle = doc.createElement("books"); // 创建一个节点

doc.appendChild(rootEle); // 挂到document上，也就是根节点

Element e = doc.createElement("book"); // 再创建一个节点

e.setAttribute("name", "疯狂java讲义"); // 给节点设置属性

rootEle.appendChild(e); // 把节点添加到创建的节点下

3.把Document写入到文件中

TransformerFactory tf = TransformerFactory.newInstance();

Transformer ts = tf.newTransformer();

DOMSource ds = new DOMSource(doc); // 要写出的资源

PrintWriter pw = new PrintWriter(new File("c.xml")); // 写出的目的地

StreamResult sr = new StreamResult(pw); // 使用result包裹流

ts.transform(ds, sr);

4.例子（Example）

package xml;

import java.io.File;

import java.io.PrintWriter;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.transform.Transformer;

import javax.xml.transform.TransformerFactory;

import javax.xml.transform.dom.DOMSource;

import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;

import org.w3c.dom.Element;

public class Writer {

public static void main(String[] args) throws Exception {

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

DocumentBuilder builder = factory.newDocumentBuilder();

Document doc = builder.newDocument(); // 创建一个新的对象

//parse(Writer.class.getClassLoader().getResourceAsStream("config.xml"));

Element rootEle = doc.createElement("books");

doc.appendChild(rootEle);

Element e = doc.createElement("book");

e.setAttribute("name", "疯狂java讲义");

rootEle.appendChild(e);

TransformerFactory tf = TransformerFactory.newInstance();

Transformer ts = tf.newTransformer();

DOMSource ds = new DOMSource(doc); // 要写出的资源

PrintWriter pw = new PrintWriter(new File("c.xml")); // 写出的目的地

StreamResult sr = new StreamResult(pw); // 使用result包裹流

ts.transform(ds, sr);

}

三、读写Document

1.创建Document对象

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

DocumentBuilder builder = factory.newDocumentBuilder();

Document document = builder.parse(

ReadXml.class.getClassLoader().getResourceAsStream("config.xml")); // 加载classpath下的xml文件生成dom树

2.对读取的Document对象进行修改

Element e = doc.getDocumentElement(); // 获得根节点

Element book = doc.createElement("book"); // 创建一个新节点

book.setAttribute("name", "疯狂HTML讲义"); // 给新的节点设置属性

e.appendChild(book); // 把新创建的节点添加到根节点下

System.out.println(e.getNodeName()); // 打印根节点的名字

3.将修改后的Document对象写入到文件

TransformerFactory tf = TransformerFactory.newInstance();

Transformer t = tf.newTransformer();

DOMSource xmlSource = new DOMSource(doc);

StreamResult sr = new StreamResult(new PrintWriter("d.xml"));

t.transform(xmlSource, sr);

4.完整事例

package xml;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;

import org.w3c.dom.Element;

import org.w3c.dom.Node;

import org.w3c.dom.NodeList;

public class ReadXml {

public static void main(String[] args) throws Exception {

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

DocumentBuilder builder = factory.newDocumentBuilder();

Document document = builder.parse(ReadXml.class.getClassLoader().getResourceAsStream("config.xml"));

Node nodeList = document.getFirstChild();

printNodeName(nodeList,"");

}

public static void printNodeName(Node node,String line){

if(node instanceof Element){

System.out.println(line + node.getNodeName());

}

if(node.hasChildNodes()){

NodeList nl = node.getChildNodes();

for(int i =0;i<nl.getLength();i++){

printNodeName(nl.item(i),line+"\t");

}

四、抽取公共方法
我们发现，每个读方法中都要进行读取文件解析为dom对象，每个写方法都要把node对象写入到一个文件中进行持久化，既然是常用的方法，那么我们就要对其进行抽取。代码如下：

package cn.anbow.utils;import java.io.File;import java.io.PrintWriter;import javax.xml.parsers.DocumentBuilder;import javax.xml.parsers.DocumentBuilderFactory;import javax.xml.transform.Transformer;import javax.xml.transform.TransformerFactory;import javax.xml.transform.dom.DOMSource;import javax.xml.transform.stream.StreamResult;import org.w3c.dom.Document;import org.w3c.dom.Node;public class DomUtils {/** * 读取xml文件转成dom对象 * @param fileName * @return */public static Document readXml(String fileName){try {DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();DocumentBuilder builder = factory.newDocumentBuilder();Document doc= builder.parse(new File(fileName));return doc;} catch (Exception e) {e.printStackTrace();throw new RuntimeException(e);}}/** * 把dom对象写入到文件中 * @param node * @param filePath */public static void writeXml(Node node,String filePath){TransformerFactory factory = TransformerFactory.newInstance();Transformer tf;try {tf = factory.newTransformer();DOMSource ds = new DOMSource(node);StreamResult sr = new StreamResult(new PrintWriter(filePath));tf.transform(ds, sr);} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}}

这样，我们使用java对xml的操作就完成了。

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