xml的增删查 dom的增改查 复杂注释
多看看 dom 的增改查。这个比前者 xml 用的多
xml的增删查
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;
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 java.io.*;
public class Ttest {
public static void main(String[] args) {
Ttest test = new Ttest();
test.getDom(); //基础 获取Dom
// test.select();
// test.add();
test.delete();
test.writer("2.xml");
// test.delete(); 必须放在 writer 的前面，否则无作用
}
private Document doc;
//查找
public void select() {
NodeList nodeBrandList = doc.getElementsByTagName("Brand");
for (int i = 0; i < nodeBrandList.getLength(); i++) {
Node nodeBrand = nodeBrandList.item(i);
Element elementBrand = (Element) nodeBrand;
System.out.println(elementBrand.getAttribute("name"));
NodeList nodeLisType = elementBrand.getChildNodes();
for (int j = 0; j < nodeLisType.getLength(); j++) {
Node nodeType = nodeLisType.item(j);
if (nodeType.getNodeType() == Element.ELEMENT_NODE) {
Element elementType = (Element) nodeType;
System.out.println(elementType.getAttribute("name"));
}
}
}
}
public void getDom() {
try {
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
doc = db.parse(new File("src/收藏信息.xml"));
} catch (ParserConfigurationException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
//添加
public void add() {
Element elementBrand = doc.createElement("Brand"); //添加Brand节点
elementBrand.setAttribute("name", "OPPO"); //用 setAttribute ，添加 name="OPPO"
Element elementType = doc.createElement("Type"); //添加Brand节点
elementType.setAttribute("name", "r200"); //用 setAttribute ，添加
elementBrand.appendChild(elementType);
doc.getElementsByTagName("PhoneInfo").item(0).appendChild(elementBrand); //将添加的置于 PhoneInfo 标签内
}
//写入
public void writer(String path) {
try {
TransformerFactory tff = TransformerFactory.newInstance();
Transformer tf = tff.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult sr = new StreamResult(new OutputStreamWriter(new FileOutputStream(path), "utf-8"));
tf.transform(source, sr);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (TransformerException e) {
e.printStackTrace();
}
}
//删除
public void delete() {
NodeList nodeBrandList = doc.getElementsByTagName("Brand");
for (int i = 0; i < nodeBrandList.getLength(); i++) {
Node nodeBrand = nodeBrandList.item(i);
// 转换属性节点
Element elementBrand = (Element) nodeBrand;
if (elementBrand.getAttribute("name").equals("苹果")) {
elementBrand.getParentNode().removeChild(elementBrand);
}
}
}
}
结果展示：
（删除 Brand 苹果）
（查询结果）
dom的增改查
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;
import javax.servlet.http.HttpServlet;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Iterator;
public class Test1 extends HttpServlet {
public static void main(String[] args) throws IOException {
Test1 test1 = new Test1();
test1.getDoc();
// test1.select(); // 依赖 getDoc ，才可以用 select
// test1.add(); // 依赖 getDoc ，才可以用 select
test1.update();
test1.writer("4.xml");
}
private Document doc;
//xml 转换成 dom
private void getDoc (){
try {
SAXReader sr = new SAXReader();
doc = sr.read(new File("src/收藏信息.xml"));
} catch (DocumentException e) {
e.printStackTrace();
}
}
public void select(){
Element elementRoot = doc.getRootElement();
Iterator<Element> iterator = elementRoot.elementIterator();
while (iterator.hasNext()){
Element elementBrand = iterator.next();
System.out.println(elementBrand.attributeValue("name"));
for (Iterator<Element>iterator1 = elementBrand.elementIterator();iterator1.hasNext();){
Element elementType = iterator1.next();
System.out.println(elementType.attributeValue("name"));
}
}
}
// 添加
public void add() {
Element elementRoot = doc.getRootElement();
Element elementBrand = elementRoot.addElement("Brand");
elementBrand.addAttribute("name", "OPPO");
Element elementType = elementRoot.addElement("Type");
elementType.addAttribute("name", "豪华");
}
// 写入
public void writer(String path) throws IOException {
FileOutputStream fis = new FileOutputStream(path);
OutputFormat out = OutputFormat.createPrettyPrint();
out.setEncoding("utf-8");
XMLWriter writer = new XMLWriter(fis,out);
writer.write(doc);
}
// 删除
public void update(){
int num = 1;
Element elementRoot = doc.getRootElement();
Iterator<Element> iterator = elementRoot.elementIterator();
while (iterator.hasNext()){
Element elementBrand = iterator.next();
elementBrand.addAttribute("id",num+"");
num++;
}
}
}
结果展示：
（查询结果）
（增加 id 值）
xml
<?xml version="1.0" encoding="GB2312"?>
<PhoneInfo>
<Brand name="华为">
<Type name="U8650"/>
<Type name="HW123"/>
<Type name="HW321"/>
</Brand>
<Brand name="苹果">
<Type name="iPhone4"/>
</Brand>
</PhoneInfo>
复杂注释
import javax.servlet.ServletException;
import javax.servlet.annotation.WebInitParam;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Enumeration;
//复杂注释 && 获取 web.xml 配置信息
@WebServlet(name="servletConfig",urlPatterns = "/dd",loadOnStartup = 0, //一定带斜杆
initParams = {@WebInitParam(name="aaa",value = "ddd"),
@WebInitParam(name="name",value = "admin"),
@WebInitParam(name="kk",value = "www")
})
public class ServletConfig extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// config配置
Enumeration<String> enume = this.getServletConfig().getInitParameterNames();
while (enume.hasMoreElements()){
String key = enume.nextElement();
System.out.println(key+"\t"+this.getServletConfig().getInitParameter(key));
}
}
}
结果展示：
