JSP学习笔记（7）_xml文件解析

ゝ一世哀愁。 2022-06-11 00:09 203阅读 0赞

**JSP学习笔记（7）\_xml文件解析**

> **关于xml文件的几种解析方法。**
> 
>   
>

**1.xml**

> **XML:   extensiable markup language   可扩展标记语言**
> 
> **特点：标记可以由用户自己随意扩展.  **
> 
> **作用：**
> 
> **1.做其它技术的配置文件**
> 
> **2.在不同语言环境下交换数据**
> 
> **注意：使用以下xml解析方法要导包**
> 
>   
>

**2.解析方法**

> **2.1 jdom**
> 
> **2.2 dom4j**
> 
> **实现：利用dom4j实现xml文件的增删查改**
> 
>     import java.io.File;
>     import java.io.FileOutputStream;
>     import java.util.List;
>     
>     import org.dom4j.Attribute;
>     import org.dom4j.Document;
>     import org.dom4j.Element;
>     import org.dom4j.io.OutputFormat;
>     import org.dom4j.io.SAXReader;
>     import org.dom4j.io.XMLWriter;
>     import org.dom4j.tree.DefaultElement;
>     
>     public class Test01 {
>     	public static void main(String[] args) throws Exception {
>     		//查看
>     		find();
>     		//增加
>     		//add();
>     		//修改
>     		//update();
>     		//删除
>     		//delete();
>     	}
> 
>     private static void delete() throws Exception {
>     		// 创建解析器
>     		SAXReader sr = new SAXReader();
>     		//解析xml文件，得到document对象
>     		Document document = sr.read(new File("src/books.xml"));
>     		//获取根节点，再获取子节点
>     		Element root = document.getRootElement();
>     		List<Element> list = root.elements();
>     		//删除方法一		
>     //		Element t=null;
>     //		//修改水浒传为88元
>     //		for (Element book : list) {
>     //			Element title = book.element("title");
>     //			if("水浒传".equals(title.getText())){
>     //				t=book;
>     //				break;
>     //			}
>     //		}
>     //		list.remove(t);
>     		//删除方法二
>     		int size = list.size();
>     		for (int i = 0; i < size; i++) {
>     			Element book = list.get(i);
>     			Element title = book.element("title");
>     			if("水浒传".equals(title.getText())) {
>     				list.remove(book);
>     				break;
>     			}
>     		}
>     		
>     		//存盘
>     		OutputFormat of = OutputFormat.createPrettyPrint();
>     		XMLWriter xw = new XMLWriter(new FileOutputStream("src/books.xml"), of);
>     		xw.write(document);
>     		
>     		System.out.println("删除成功！");
>     	}
>     
>     	private static void update() throws Exception {
>     		// 创建解析器
>     		SAXReader sr = new SAXReader();
>     		//解析xml文件，得到document对象
>     		Document document = sr.read(new File("src/books.xml"));
>     		//获取根节点，再获取子节点
>     		Element root = document.getRootElement();
>     		List<Element> list = root.elements();
>     		Element t=null;
>     		//修改水浒传为88元
>     		for (Element book : list) {
>     			Element title = book.element("title");
>     			if("水浒传".equals(title.getText())){
>     				Element price = book.element("price");
>     				price.setText("88");
>     				break;
>     			}
>     		}
>     		
>     		//存盘
>     		OutputFormat of = OutputFormat.createPrettyPrint();
>     		XMLWriter xw = new XMLWriter(new FileOutputStream("src/books.xml"), of);
>     		xw.write(document);
>     		
>     		System.out.println("修改成功！");
>     	}
>     
>     	private static void add() throws Exception {
>     		// 创建解析器
>     		SAXReader sr = new SAXReader();
>     		//解析xml文件，得到document对象
>     		Document document = sr.read(new File("src/books.xml"));
>     		//获取根节点，再获取子节点
>     		Element root = document.getRootElement();
>     		List<Element> list = root.elements();
>     		
>     		Element book = new DefaultElement("book");
>     		Element title = new DefaultElement("title");
>     		Element price = new DefaultElement("price");
>     		Element description = new DefaultElement("description");
>     		price.setAttributeValue("unit","元");
>     		
>     		title.setText("水浒传");
>     		price.setText("55");
>     		description.setText("3个女人和105个男人的故事");
>     		book.add(title);
>     		book.add(price);
>     		book.add(description);
>     		list.add(book);
>     		
>     		//存盘
>     		OutputFormat of = OutputFormat.createPrettyPrint();
>     		XMLWriter xw = new XMLWriter(new FileOutputStream("src/books.xml"), of);
>     		xw.write(document);
>     		
>     		System.out.println("添加成功！");
>     	}
>     
>     	private static void find() throws Exception {
>     		// 创建解析器
>     		SAXReader sr = new SAXReader();
>     		//解析xml文件，得到document对象
>     		Document document = sr.read(new File("src/books.xml"));
>     		//获取根节点，再获取子节点
>     		Element root = document.getRootElement();
>     		List<Element> list = root.elements();
>     		for (Element book : list) {
>     			System.out.println("-----------------------");
>     			System.out.println(book.getName());
>     			Element title = book.element("title");
>     			Element price = book.element("price");
>     			Attribute unit = price.attribute("unit");
>     			Element description = book.element("description");
>     			
>     			System.out.println("title:"+title.getText());
>     			System.out.println("price:"+price.getText()+unit.getValue());
>     			System.out.println("description:"+description.getText());
>     		}
>     		
>     	}
>     }
> 
>   
>   
> 
> 
> **2.3 sax**
> 
> **实现：利用sax实现xml文件解析-查看书名“title”**
> 
>     import javax.xml.parsers.SAXParser;
>     
>     import org.apache.xerces.jaxp.SAXParserFactoryImpl;
>     import org.xml.sax.Attributes;
>     import org.xml.sax.SAXException;
>     import org.xml.sax.XMLReader;
>     import org.xml.sax.helpers.DefaultHandler;
>     
>     public class Test{
>     	public static void main(String[] args) throws Exception {
>     		find();
>     	}
>     
>     	private static void find() throws Exception {
>     		//创建解析器
>     		SAXParserFactoryImpl spf = new SAXParserFactoryImpl();
>     		SAXParser sp = spf.newSAXParser();
>     		XMLReader reader = sp.getXMLReader();
>     		//设置事件
>     		reader.setContentHandler(new DefaultHandler(){
>     			private String flag;
>     			@Override
>     			//碰到标记开始
>     			public void startElement(String uri, String localName,
>     					String qName, Attributes attributes) throws SAXException {
>     				// TODO Auto-generated method stub
>     				super.startElement(uri, localName, qName, attributes);
>     				flag = qName;
>     			}
>     			@Override
>     			//碰到内容开始
>     			public void characters(char[] ch, int start, int length)
>     					throws SAXException {
>     				// TODO Auto-generated method stub
>     				super.characters(ch, start, length);
>     				if("title".equals(flag)){
>     					System.out.println(new String(ch,start,length));
>     				}
>     			}
>     			@Override
>     			//碰到结束标志开始
>     			public void endElement(String uri, String localName, String qName)
>     					throws SAXException {
>     				// TODO Auto-generated method stub
>     				super.endElement(uri, localName, qName);
>     			}
>     		});
>     		
>     		//使用reader去解析一个xml文件，这是没有document对象生成
>     		reader.parse("src/books.xml");
>     	}
>     }
> 
> 截图：
> 
> **![Center][]**  
>   
>

> **2.4 Xpath的部分实例**
> 
>     import java.io.File;
>     import java.util.List;
>     
>     import org.dom4j.Document;
>     import org.dom4j.DocumentException;
>     import org.dom4j.Element;
>     import org.dom4j.io.SAXReader;
>     
>     public class Test {
>     	public static void main(String[] args) throws Exception {
>     		//test1();
>     		//test2();
>     		//test3();
>     		//test4();
>     		//test5();
>     		//test6();
>     		//test7();
>     		//test8();
>     		//test9();
>     		test10();
>     	}
>     
>     	private static void test10() throws Exception {
>     		//创建解析器
>     		SAXReader sr = new SAXReader();
>     		//解析xml文件
>     		Document read = sr.read(new File("src/test10.xml"));
>     		//使用Xpath
>     		List<Element> list = read.selectNodes("//CCC|//BBB");
>     		for (Element element : list) {
>     			System.out.println(element.getName());
>     		}
>     		
>     	}
>     
>     	private static void test9() throws Exception {
>     		//创建解析器
>     		SAXReader sr = new SAXReader();
>     		//解析xml文件
>     		Document read = sr.read(new File("src/test9.xml"));
>     		//使用Xpath
>     		List<Element> list = read.selectNodes("//*[string-length(name()) = 3]");
>     		for (Element element : list) {
>     			System.out.println(element.getName());
>     		}
>     	}
>     
>     	private static void test8() throws Exception {
>     		//创建解析器
>     		SAXReader sr = new SAXReader();
>     		//解析xml文件
>     		Document read = sr.read(new File("src/test8.xml"));
>     		//使用Xpath
>     		List<Element> list = read.selectNodes("//*[name()='BBB']");
>     		for (Element element : list) {
>     			System.out.println(element.getName());
>     		}
>     	}
>     
>     	private static void test7() throws Exception {
>     		//创建解析器
>     		SAXReader sr = new SAXReader();
>     		//解析xml文件
>     		Document read = sr.read(new File("src/test7.xml"));
>     		//使用Xpath//*[count(BBB)=2]
>     		List<Element> list = read.selectNodes("//*[count(BBB)=2]");
>     		for (Element element : list) {
>     			System.out.println(element.getName());
>     		}
>     	}
>     
>     	private static void test6() throws Exception {
>     		//创建解析器
>     		SAXReader sr = new SAXReader();
>     		//解析xml文件
>     		Document read = sr.read(new File("src/test6.xml"));
>     		//使用Xpath
>     		List<Element> list = read.selectNodes("//BBB[@id='b1']");
>     		for (Element element : list) {
>     			System.out.println(element.getName());
>     		}
>     	}
>     
>     	private static void test5() throws Exception {
>     		//创建解析器
>     		SAXReader sr = new SAXReader();
>     		//解析xml文件
>     		Document read = sr.read(new File("src/test5.xml"));
>     		//使用Xpath
>     		List<Element> list = read.selectNodes("//BBB[@id]");
>     		
>     		for (Element element : list) {
>     			System.out.println(element.getName());
>     		}
>     	}
>     
>     	private static void test4() throws Exception {
>     		//创建解析器
>     		SAXReader sr = new SAXReader();
>     		//解析xml文件
>     		Document read = sr.read(new File("src/test4.xml"));
>     		//使用Xpath
>     		List<Element> list = read.selectNodes("/AAA/BBB[1]");
>     		for (Element element : list) {
>     			System.out.println(element.getName());
>     		}
>     	}
>     
>     	private static void test3() throws Exception {
>     		//创建解析器
>     		SAXReader sr = new SAXReader();
>     		//解析xml文件
>     		Document read = sr.read(new File("src/test3.xml"));
>     		//Xpath
>     		List<Element> list = read.selectNodes("/AAA/CCC/DDD/*");
>     		for (Element element : list) {
>     			System.out.println(element.getName());
>     		}
>     	}
>     
>     	private static void test2() throws Exception {
>     		//创建解析器
>     		SAXReader sr = new SAXReader();
>     		//解析xml文件
>     		Document read = sr.read(new File("src/test2.xml"));
>     		//使用Xpath
>     		List<Element> list = read.selectNodes("//BBB");
>     		for (Element element : list) {
>     			System.out.println(element.getName());
>     		}
>     	}
>     
>     	private static void test1() throws Exception {
>     		//创建解析器
>     		SAXReader sr = new SAXReader();
>     		//解析xml文件
>     		Document document = sr.read(new File("src/test1.xml"));
>     		//使用Xpath
>     		List<Element> list = document.selectNodes("/AAA");
>     		//遍历打印
>     		for (Element element : list) {
>     			System.out.println(element.getName());
>     		}
>     	}
>     }
> 
>   
> 
> 
>   
>

[Center]: /images/20220611/4c6fedd647fa411da5ee47e4f8d81eb5.png