dom4j的特點：必須一層一層獲取。
package cn.itcast.sax;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;
public class Demo3 {
public static void main(String[] args) throws IOException, SAXException, ParserConfigurationException {
//獲得解析工廠
SAXParserFactory factory = SAXParserFactory.newInstance();
//得到解析器
SAXParser sp = factory.newSAXParser();
//得到讀取器
XMLReader reader = sp.getXMLReader();
//設置內容處理器(implements Contenthandler或extends DefaultHandler)
reader.setContentHandler(new BeanListHandler());
//讀取XML文檔內容
reader.parse("src/book.xml");
//把XML文檔中的每一本書封裝到一個book對象，並把多個book對象放在一個list集合返回
}
}
class BeanListHandler extends DefaultHandler {
private List list = new ArrayList();
private String currentTag;
private Book book;
@Override
public void startElement(String uri, String localName, String name,
Attributes attributes) throws SAXException {
// TODO Auto-generated method stub
currentTag = name;
if ("書".equals(currentTag)) {
book = new Book();
}
}
@Override
public void characters(char[] ch, int start, int length)
throws SAXException {
if ("書名".equals(currentTag)) {
String name = new String(ch, start, length);
book.setName(name);
}
if ("作者".equals(currentTag)) {
String author = new String(ch, start, length);
book.setAuthor(author);
}
if ("售價".equals(currentTag)) {
String price = new String(ch, start, length);
book.setAuthor(price);
}
}
@Override
public void endElement(String uri, String localName, String qName)
throws SAXException {
if ("書".equals("name")) {
list.add(book);
book = null;
}
currentTag = null;
}
public List getList(){
return list;
}
}
publicclass Demo1 {
/* @Test
public void readAttr() throws DocumentException{
SAXReader reader=new SAXReader();
Document document=reader.read(new File("src/book.xml"));
Element root=document.getRootElement();
Element book=(Element)root.element("書").get(1);
String value=book.element("書名").attribute("name").getValue();
System.out.println(value);
}*/
@Test
publicvoid add()throws DocumentException, IOException{
SAXReader reader=new SAXReader();
Document document=reader.read(new File("src/book.xml"));
Element book=document.getRootElement().element("書");
book.addElement("售價").setText("209元");
OutputFormat format=OutputFormat.createPrettyPrint();
format.setEncoding("UTF-8");
XMLWriter writer=new XMLWriter(new FileOutputStream("src/book.xml"),format);
writer.write(document);
writer.close();
}
}
//在第一本書指定位置添加一個新的售價：<售價>209元</售價>--更改保存了所有孩子的list集合的順序
@Test
publicvoidadd2()throws DocumentException, IOException{
SAXReader reader=new SAXReader();
Document document=reader.read(new File("src/book.xml"));
Element book=document.getRootElement().element("書");
List list=book.elements();
Element price=DocumentHelper.createElement("售價");
price.setText("309元");
list.add(2,price);
OutputFormat format=OutputFormat.createPrettyPrint();
format.setEncoding("UTF-8");
XMLWriter writer=new XMLWriter(new FileOutputStream("src/book.xml"),format);
writer.write(document);
writer.close();
}
//刪除指定節點
@Test
publicvoid delete()throws DocumentException, IOException{
SAXReader reader=new SAXReader();
Document document=reader.read(new File("src/book.xml"));
Element price=document.getRootElement().element("書").element("售價");
price.getParent().remove(price);
OutputFormat format=OutputFormat.createPrettyPrint();
format.setEncoding("UTF-8");
XMLWriter writer= new XMLWriter(new FileOutputStream("src/book.xml"),format);
writer.write(document);
writer.close();
}
//更新信息
publicvoid update()throws Exception{
SAXReader reader=new SAXReader();
Document document=reader.read(new File("src/book.xml"));
Element book=(Element) document.getRootElement().elements("書").get(1);
book.element("作者").setText("黎活明");
OutputFormat format=OutputFormat.createPrettyPrint();
format.setEncoding("UTF-8");
XMLWriter writer= new XMLWriter(new FileOutputStream("src/book.xml"),format);
writer.write(document);
writer.close();
}
XPath
用XPath模擬登陸
publicclass Demo5 {
publicstaticvoid main(String[] args)throws Exception{
String username="aaa";
String password="123";
//檢測XML文檔是否有匹配的用戶名和密碼
SAXReader reader=new SAXReader();
Document document=reader.read(new File("src/users.xml"));
Node node=document.selectSingleNode("//user[@username='"+username+"' and @password='"+password+"']");
if(node==null){
System.out.println("您輸入的用戶名或密碼有誤");
}
else{
System.out.println("登陸成功");
}
}
}
XML Schema
XML Schema文件自身就是一個XML文件，擴展名爲.xsd
一個XML Schema文檔通常稱之爲模式文檔（約束文檔），遵循這個文檔書寫的XML文件稱之爲實例文檔！
在XML Schema中，每個約束模式文檔都可以被賦以一個唯一的名稱空間，名稱空間用一個唯一的URI（Uniform Resource Identifier，統一資源標識符）表示。
Schema 語法：
定義簡單元素：<xs:element name=”XXXX” type=”yyy”/>
XXX:元素的名稱，yyy:元素的數據類型
最常用的類型：
xs:string /xs:decimal/xs:integer/xs:boolean/xs:date/xs:time
一道打印M的面試題（平面圖形題--通用解題方案：利用二維數組）
publicclass MTest {
publicstaticvoid main(String[] args){
int x=2;
int y=0;
boolean flag=true;
int arr[][]=newint[3][9];
for(int i=1;i<=9;i++){
arr[x][y]=i;
y++;
if(flag==false){
x--;
}
if(flag==true){
x++;
}
if(x<0){
flag=true;
x+=2;
}
if(x>2){
flag=false;
x-=2;
}
}
for(int i=0;i<arr.length;i++){
for(int j=0;j<arr[i].length;j++){
if(arr[i][j]==0){
System.out.print(" ");
}else{
System.out.print(arr[i][j]);
}
}
System.out.println();
}
}
}
