Jaxp的dom解析

package cn.itcast.jaxp;


import java.io.File;
import java.io.IOException;


import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
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;
import org.xml.sax.SAXException;


public class Demo1 {


/**使用jaxp操作xml文档
* @param args
* @throws ParserConfigurationException 
* @throws IOException 
* @throws SAXException 
*/
public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException {

//1.获取工厂
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();


//2.产生解析器
DocumentBuilder builder = factory.newDocumentBuilder();

//3.解析xml文档，得到代表文档的document
Document document = builder.parse(new File("src/book1.xml"));


//遍历
list(document);
}

//得到售价结点的值
@Test
public void read() throws Exception{

//1.获取工厂
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document document = builder.parse(new File("src/book.xml"));

NodeList list = document.getElementsByTagName("售价");
Node price = list.item(0);

String value = price.getTextContent();
System.out.println(value);
}

//修改结点的值:<售价>39.00元</售价>改为109
@Test
public  void update() throws Exception{

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder  builder = factory.newDocumentBuilder();
Document document = builder.parse(new File("src/book1.xml"));

Node price = document.getElementsByTagName("售价").item(0);
price.setTextContent("109");


//把内存中的document写到xml文档
TransformerFactory tf = TransformerFactory.newInstance();
//得到转换器
Transformer ts = tf.newTransformer();
ts.transform(new DOMSource(document), new StreamResult(new File("src/book1.xml")));
}


//向指定节点中增加孩子节点（售价节点）
@Test
public void add() throws Exception{
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder  builder = factory.newDocumentBuilder();
Document document = builder.parse(new File("src/book1.xml"));

//创建需要增加的节点
Node price = document.createElement("售价");
price.setTextContent("59元");

//得到需要增加的节点的父亲
Node parent = document.getElementsByTagName("书").item(0);

//把需要增加的节点挂到父结点上
parent.appendChild(price);


TransformerFactory tf = TransformerFactory.newInstance();
Transformer ts = tf.newTransformer();
ts.transform(new DOMSource(document), new StreamResult(new File("src/book1.xml")));


}

//向指定位置上插入售价节点
@Test
public void add2() throws Exception{
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder  builder = factory.newDocumentBuilder();
Document document = builder.parse(new File("src/book1.xml"));

Node node = document.createElement("售价");
node.setTextContent("39元");

Node parent = document.getElementsByTagName("书").item(0);
parent.insertBefore(node, document.getElementsByTagName("书名").item(0));

TransformerFactory tf = TransformerFactory.newInstance();
Transformer ts = tf.newTransformer();
ts.transform(new DOMSource(document), new StreamResult(new File("src/book1.xml")));
}

//删除xml文档的售价结点
@Test
public void delete() throws Exception{
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder  builder = factory.newDocumentBuilder();
Document document = builder.parse(new File("src/book1.xml"));

Node node = document.getElementsByTagName("售价").item(2);
node.getParentNode().removeChild(node);

TransformerFactory tf = TransformerFactory.newInstance();
Transformer ts = tf.newTransformer();
ts.transform(new DOMSource(document), new StreamResult(new File("src/book1.xml")));
}

//操作xml文档属性
@Test
public void updateAttribute() throws Exception{
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder  builder = factory.newDocumentBuilder();
Document document = builder.parse(new File("src/book1.xml"));


//操作xml文档的元素时，一般都把元素当作node对象，但是程序员如果发现node不好使时，就应把node强转成相应类型
Node node  = document.getElementsByTagName("书").item(0);
Element book = null;
if(node.getNodeType()==Node.ELEMENT_NODE){  //在作结点转换之前，最好先判断结点类型
book  = (Element)node;
}

book.setAttribute("name", "yyyyyyy");
book.setAttribute("password", "123");
book.removeAttribute("password");

TransformerFactory tf = TransformerFactory.newInstance();
Transformer ts = tf.newTransformer();
ts.transform(new DOMSource(document), new StreamResult(new File("src/book1.xml")));
}

//遍历
public static void list(Node node){

if(node.getNodeType()==Node.ELEMENT_NODE){
System.out.println(node.getNodeName());
}

NodeList list = node.getChildNodes();
for(int i=0;i<list.getLength();i++){
Node child = list.item(i);
list(child);
}
}



}