web学习第二天

DTD语法

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Dom和sax

Dom和sax解析方法的区别：

1，dom解析的优点是对文档crud比较方便，缺点是占用内存比较大

2，sax解析的优点是占用内存少，解析熟读快，缺点是只适合做文档的读取，不适合crud

JAXP对XML文档进行DOM解析

Xml：

<?xml version="1.0" encoding="UTF-8" standalone="no"?><书架>

<书>

<书名 name="小黄书">Java就业培训教程</书名>

<作者>张兆祥</作者>

<售价>59yuan</售价>

<售价>39</售价>

<售价>59yuan</售价></书>

<书>

<书名>JavaScript网页开发</书名>

<作者>张兆祥</作者>

<售价>12</售价>

</书>

</书架>

代码

package day2;

import java.io.FileOutputStream;

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.junit.Test;

import org.w3c.dom.Document;

import org.w3c.dom.Element;

import org.w3c.dom.Node;

import org.w3c.dom.NodeList;

//使用dom方式对xml文档进行crud

public class bookdemo {

@Test

public void read1()throws Exception {

DocumentBuilderFactoryfactory=DocumentBuilderFactory.newInstance();

DocumentBuilderbuilder=factory.newDocumentBuilder();

Documentdocument=(Document)builder.parse("src/day2/book.xml");

NodeListlist=document.getElementsByTagName("书名");

Nodenode=list.item(1);

Stringcontent=node.getTextContent();

System.out.println(content);

}

//得到xml文件中所有标签

@Test

public void read2()throws Exception {

DocumentBuilderFactoryfactory=DocumentBuilderFactory.newInstance();

DocumentBuilderbuilder=factory.newDocumentBuilder();

Documentdocument=(Document)builder.parse("src/day2/book.xml");

//得到根节点

Noderoot=document.getElementsByTagName("书架").item(0);

list(root);

}

private void list(Nodenode) {

if(node instanceof Element) {

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

}

NodeListlist=node.getChildNodes();

for(int i=0;i<list.getLength();i++) {

Nodechild=list.item(i);

list(child);

}

}

//得到xml文档中标签属性的值：<书名 name="hahaha">Java就业培训教程</书名>

@Test

public void read3()throws Exception {

DocumentBuilderFactoryfactory=DocumentBuilderFactory.newInstance();

DocumentBuilderbuilder=factory.newDocumentBuilder();

Documentdocument=(Document)builder.parse("src/day2/book.xml");

Elementbookname=(Element)document.getElementsByTagName("书名").item(0);

Stringvalue=bookname.getAttribute("name");

System.out.println(value);

}

//向xml文档中添加节点：<售价>59yuan</售价>

@Test

public void add()throws Exception {

DocumentBuilderFactoryfactory=DocumentBuilderFactory.newInstance();

DocumentBuilderbuilder=factory.newDocumentBuilder();

Documentdocument=(Document)builder.parse("src/day2/book.xml");

//创建节点

Elementprice=document.createElement("售价");

price.setTextContent("59yuan");

//把创建的节点挂到第一本书上

Elementbook=(Element)document.getElementsByTagName("书").item(0);

book.appendChild(price);

//把更新的内存写回到xml文档中

TransformerFactoryttfactory=TransformerFactory.newInstance();

Transformertf=ttfactory.newTransformer();

tf.transform(new DOMSource(document),new StreamResult(new FileOutputStream("src/day2/book.xml")));

}

//向xml文档指定位置上添加节点：<售价>59yuan</售价>

@Test

public void add1()throws Exception {

DocumentBuilderFactoryfactory=DocumentBuilderFactory.newInstance();

DocumentBuilderbuilder=factory.newDocumentBuilder();

Documentdocument=(Document)builder.parse("src/day2/book.xml");

//创建节点

Elementprice=document.createElement("售价");

price.setTextContent("59yuan");

//得到参考节点

ElementrefNode=(Element)document.getElementsByTagName("售价").item(0);

//得到想要挂载的节点//把创建的节点挂到第一本书上

Elementbook=(Element)document.getElementsByTagName("书").item(0);

book.appendChild(price);

//往book节点的指定位置插

book.insertBefore(price,refNode);

//把更新的内存写回到xml文档中

TransformerFactoryttfactory=TransformerFactory.newInstance();

Transformertf=ttfactory.newTransformer();

tf.transform(new DOMSource(document),new StreamResult(new FileOutputStream("src/day2/book.xml")));

}

//向xml文档节点中添加属性：<书名 >Java就业培训教程</书名>  name="小黄书"

@Test

public void addAtrr()throws Exception {

DocumentBuilderFactoryfactory=DocumentBuilderFactory.newInstance();

DocumentBuilderbuilder=factory.newDocumentBuilder();

Documentdocument=(Document)builder.parse("src/day2/book.xml");

Elementbookname=(Element)document.getElementsByTagName("书名").item(0);

bookname.setAttribute("name","小黄书");

//把更新的内存写回到xml文档中

TransformerFactoryttfactory=TransformerFactory.newInstance();

Transformertf=ttfactory.newTransformer();

tf.transform(new DOMSource(document),new StreamResult(new FileOutputStream("src/day2/book.xml")));

}

//删除节点：<售价>39</售价>

@Test

public void delete()throws Exception {

Documentdocument=DocumentBuilderFactory.newInstance().newDocumentBuilder().parse("src/day2/book.xml");

//得到要删除的节点

Elementprice=(Element)document.getElementsByTagName("售价").item(1);

price.getParentNode().removeChild(price);

/*//得到要删除节点的爸爸

Element book=(Element) document.getElementsByTagName("书").item(0);

book.removeChild(price);*/

//把更新的内存写回到xml文档中

TransformerFactoryttfactory=TransformerFactory.newInstance();

Transformertf=ttfactory.newTransformer();

tf.transform(new DOMSource(document),new StreamResult(new FileOutputStream("src/day2/book.xml")));

}

//更新售价

@Test

public void update()throws Exception {

Documentdocument=DocumentBuilderFactory.newInstance().newDocumentBuilder().parse("src/day2/book.xml");

//得到要删除的节点

Elementprice=(Element)document.getElementsByTagName("售价").item(1);

price.setTextContent("一百元");

//把更新的内存写回到xml文档中

TransformerFactoryttfactory=TransformerFactory.newInstance();

Transformertf=ttfactory.newTransformer();

tf.transform(new DOMSource(document),new StreamResult(new FileOutputStream("src/day2/book.xml")));

}

}

web学习第二天

原文地址：http://www.cnblogs.com/free20019/p/7637075.html