XML解析

DOM的编程API：

Node:节点

Document :根节点 表示整个文档

NodeList:节点的集合

NamedNodeMap:一般用于存储属性

Element:

Text

Attr

编程思路:

1.获得DocumentBuilderFactory的实例

2.通过工厂获得DocumentBuilder的解析器

3.parse(File)======>Document

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importjavax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import java.io.*;

import org.w3c.dom.Document;

import org.w3c.dom.NodeList;

import org.w3c.dom.Node;

import org.w3c.dom.Element;

import org.w3c.dom.Attr;

import org.w3c.dom.NamedNodeMap;

//通过DOM方式解析XML文档

public class MyDom{

publicstatic void main(String args[])throws Exception{

//1.得到工厂类（DocumentBuilderFactory）的实例

DocumentBuilderFactoryfactory=DocumentBuilderFactory.newInstance();

//2.得到解析器实例

DocumentBuilder builder=factory.newDocumentBuilder();

//3.使用parse（）解析文件 返回 文档的根节点Document

Documentdoc=builder.parse(new File("student.xml"));

Element root=doc.getDocumentElement();

System.out.println("根元素是："+root.getTagName());

NodeListnl=doc.getElementsByTagName("student");

//NodeListnl=root.getChildNodes();

//遍历NodeList

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

Node node=nl.item(i); //得到Node集合中的每一个

NamedNodeMap nnm=node.getAttributes();

for(int j=0;j<nnm.getLength();j++){

Nodeatt_node=nnm.item(j);

Attrattr=(Attr)att_node;

Stringatt_name=attr.getName();

Stringattvalue=attr.getValue();

System.out.println(att_name+"="+att_value);

}

Element first=(Element)node;

System.out.println(first.getTagName());

//得到每个student元素的子节点

NodeList secs=node.getChildNodes();

System.out.println(secs.getLength());

for(intk=0;k<secs.getLength();k++){

//得到二级子节点

Node sec_node=secs.item(k);

//过滤空白

if(sec_node.getNodeType()==Node.ELEMENT_NODE){

Elementsec=(Element)sec_node;

System.out.println(sec.getTagName());

System.out.println(sec.getTextContent());

}

}

}

}

}

 

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DOM 创建文档

---------------Create.java---------

import javax.xml.parsers.*;

import java.io.*;

import org.w3c.dom.*;

import javax.xml.transform.*;

importjavax.xml.transform.dom.DOMSource;

importjavax.xml.transform.stream.StreamResult;

public class Create{

publicstatic void main(String args[])throws Exception{

//1.获得工厂实例

DocumentBuilderFactoryf=DocumentBuilderFactory.newInstance();

//2.得到解析器

DocumentBuilder builder=f.newDocumentBuilder();

//3.builder.newDocument();

Document doc=builder.newDocument();

//创建元素

Element root=doc.createElement("emps");

Elementemp1=doc.createElement("emp");

Elementname1=doc.createElement("name");

name1.setTextContent("etoak");

Elementemail1=doc.createElement("email");

email1.setTextContent("email1");

Elementemp2=doc.createElement("emp");

Elementname2=doc.createElement("name");

name2.setTextContent("etoak1");

Elementemail2=doc.createElement("email");

email2.setTextContent("email1");

//组装 appendChild() Node

doc.appendChild(root);

root.appendChild(emp1);

root.appendChild(emp2);

emp1.appendChild(name1);

emp1.appendChild(email1);

emp2.appendChild(name2);

emp2.appendChild(email2);

//将DOcument实例 持久化到磁盘上

//1.TransformerFactory 实例 newInstance();

TransformerFactory factory=TransformerFactory.newInstance();

//2.factory实例得到 Transformer 实例

Transformer former=factory.newTransformer();

former.setOutputProperty(OutputKeys.INDENT,"yes");

//构造源

DOMSource source=new DOMSource(doc);

//构造结果 类型stream

StreamResult result=new StreamResult(newFile("emp.xml"));

former.transform(source,result);

}

}