xml的增删改查

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;

public class Demo3 {

//读取xml文档中的标签
@Test
public void read() throws Exception{
//1、创建工厂
DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
//2、得到dom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("src/enumration/nan/book.xml");
NodeList list=document.getElementsByTagName_r("书名");
Node node=list.item(0);
String content=node.getTextContent();
System.out.println(content);

}
@Test
public void test2() throws Exception{
DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
DocumentBuilder builder=factory.newDocumentBuilder();
Document document=builder.parse("src/enumration/nan/book.xml");
//得到根节点
Node root=document.getElementsByTagName_r("书架").item(0);
list(root);
}
private void list(Node node){
if(node instanceof Element){
System.out.println(node.getNodeName());
}
NodeList list=node.getChildNodes();
for(int i=0;i<list.getLength();i++){
Node child=list.item(i);
list(child);
}
}

//得到xml文档中的标签属性值
@Test
public void test3() throws Exception{
DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
DocumentBuilder builder=factory.newDocumentBuilder();
Document document=builder.parse("src/enumration/nan/book.xml");

Element bookname=(Element) document.getElementsByTagName_r("书名").item(0);
String name=bookname.getAttribute("name");
System.out.println(name);
}

//向xml文档中添加结点：
@Test
public void add() throws Exception{
DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
DocumentBuilder builder=factory.newDocumentBuilder();
Document document=builder.parse("src/enumration/nan/book.xml");
//创建节点
Element price=document.createElement_x("售价");
price.setTextContent("59.00元");

//把创建的节点挂到第一本书上
Element book=(Element)document.getElementsByTagName_r("书").item(0);
book.appendChild(price);

//把更新后内存写回到xml文档
TransformerFactory tfactory=TransformerFactory.newInstance();
Transformer tf=tfactory.newTransformer();
tf.transform(new DOMSource(document),new StreamResult(new FileOutputStream("src/enumration/nan/book.xml")));
}
//向xml文档中指定位置插入
@Test
public void add2() throws Exception{
DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
DocumentBuilder builder=factory.newDocumentBuilder();
Document document=builder.parse("src/enumration/nan/book.xml");

//创建节点
Element price=document.createElement_x("售价");
price.setTextContent("53.00元");

//得到要参考节点
Element refNode=(Element) document.getElementsByTagName_r("售价").item(0);

//得到要挂孩子的节点
Element book=(Element) document.getElementsByTagName_r("书").item(0);

//往book节点的指定位置插入
book.insertBefore(price,refNode);

//把更新后内存写回到xml文档中

TransformerFactory tfactory=TransformerFactory.newInstance();
Transformer tf=tfactory.newTransformer();
tf.transform(new DOMSource(document),new StreamResult(new FileOutputStream("src/enumration/nan/book.xml")));
}

//向xml文档节点中添加属性：
@Test
public void addAttr() throws Exception{
DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
DocumentBuilder builder=factory.newDocumentBuilder();
Document document=builder.parse("src/enumration/nan/book.xml");

Element bookname=(Element) document.getElementsByTagName_r("书名").item(0);
bookname.setAttribute("name","xxx");

//把更新后内存写回到xml文档
TransformerFactory tfactory=TransformerFactory.newInstance();
Transformer tf=tfactory.newTransformer();
tf.transform(new DOMSource(document),new StreamResult(new FileOutputStream("src/enumration/nan/book.xml")));
}

@Test
public void delete() throws Exception{
DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
DocumentBuilder builder=factory.newDocumentBuilder();
Document document=builder.parse("src/enumration/nan/book.xml");

//得到要删除的节点
Element e=(Element) document.getElementsByTagName_r("售价").item(0);

//得到要删除的节点的父节点
Element book=(Element) document.getElementsByTagName_r("书").item(0);

//父节点再删孩子
book.removeChild(e);

//再把删除后的写回到内存中
TransformerFactory tfactory=TransformerFactory.newInstance();
Transformer tf=tfactory.newTransformer();
tf.transform(new DOMSource(document),new StreamResult(new FileOutputStream("src/enumration/nan/book.xml")));
}

//删整个xml文件
@Test
public void delete2() throws Exception{
DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
DocumentBuilder builder=factory.newDocumentBuilder();
Document document=builder.parse("src/enumration/nan/book.xml");

//得到要删除的节点
Element e=(Element) document.getElementsByTagName_r("售价").item(0);
//e.getParentNode().removeChild(e);
//e.getParentNode().getParentNode().removeChild(e.getParentNode());这个是把书给删了
e.getParentNode().getParentNode().getParentNode().removeChild(e.getParentNode().getParentNode());
//把更新后写回到内存中
TransformerFactory tfactory=TransformerFactory.newInstance();
Transformer tf=tfactory.newTransformer();
tf.transform(new DOMSource(document),new StreamResult(new FileOutputStream("src/enumration/nan/book.xml")));
}

//更新xml文件
@Test
public void update() throws Exception{
DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
DocumentBuilder builder=factory.newDocumentBuilder();
Document document=builder.parse("src/enumration/nan/book.xml");

//得到要更新的数据
Element price=(Element) document.getElementsByTagName_r("售价").item(0);

price.setTextContent("109");

//更新后写回到内存中
TransformerFactory tfactory=TransformerFactory.newInstance();
Transformer tf=tfactory.newTransformer();
tf.transform(new DOMSource(document),new StreamResult(new FileOutputStream("src/enumration/nan/book.xml")));

} }