javaweb-day01-7（XML 解析-案例）

1、以如下格式的exam.xml文件为例

exam.xml

<?xml version="1.0" encoding="UTF-8" standalone="no"?><exam><student examid="222" idcard="111"><name>张三</name><location>沈阳</location><grade>89.00</grade></student><student examid="444" idcard="333"><name>李四</name><location>大连</location><grade>97.00</grade></student></exam>

２、编程实现如下功能

 

３、实现学生信息的添加

 

４、实现学生信息的查询

 

５、实现学生的删除功能

 

 

添加数据：

查询数据：

 

开发顺序：先写javabean，再写Dao用到的工具类、Dao ，最后写界面层Main。

不同模块的程序，要放在不同的包里：

•   实体javabean：放在domain包。
•   Dao：放在dao包。dao操作xml文档必定会有重复代码：得到document、更新xml文档。将他们抽取到工具类XmlUtils里。
•   工具类XmlUtils：放在utils工具包中。
•   界面Main：放在main包。

 

 

Student.java

package cn.mengmei.domain;public class Student {private String idcard;private String examid;private String name;private String location;private Double grade;public String getIdcard() {return idcard;}public void setIdcard(String idcard) {this.idcard = idcard;}public String getExamid() {return examid;}public void setExamid(String examid) {this.examid = examid;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getLocation() {return location;}public void setLocation(String location) {this.location = location;}public Double getGrade() {return grade;}public void setGrade(Double grade) {this.grade = grade;}}

XMLUtils.java

package cn.mengmei.utils;import java.io.IOException;import javax.xml.parsers.DocumentBuilderFactory;import javax.xml.parsers.ParserConfigurationException;import javax.xml.transform.TransformerConfigurationException;import javax.xml.transform.TransformerException;import javax.xml.transform.TransformerFactory;import javax.xml.transform.TransformerFactoryConfigurationError;import javax.xml.transform.dom.DOMSource;import javax.xml.transform.stream.StreamResult;import org.w3c.dom.Document;import org.xml.sax.SAXException;public class XMLUtils {public static Document document() throws SAXException, IOException, ParserConfigurationException  {Document document = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse("src/exam.xml");return document;}public static void updateXML(Document document) throws TransformerConfigurationException, TransformerException, TransformerFactoryConfigurationError  {TransformerFactory.newInstance().newTransformer().transform(new DOMSource(document), new StreamResult("src/exam.xml"));}}

 

StudentDao.java

package cn.mengmei.dao;import org.w3c.dom.Document;import org.w3c.dom.Element;import org.w3c.dom.Node;import org.w3c.dom.NodeList;import cn.mengmei.domain.Student;import cn.mengmei.utils.XMLUtils;public class StudentDao {public void add(Student student) {try {Document document = XMLUtils.document();Element stuNode = document.createElement("student");stuNode.setAttribute("idcard", student.getIdcard());stuNode.setAttribute("examid", student.getExamid());Element nameNode = document.createElement("name");nameNode.setTextContent(student.getName());Element locNode = document.createElement("location");locNode.setTextContent(student.getLocation());Element graNode = document.createElement("grade");graNode.setTextContent(student.getGrade()+"");stuNode.appendChild(nameNode);stuNode.appendChild(locNode);stuNode.appendChild(graNode);document.getDocumentElement().appendChild(stuNode);XMLUtils.updateXML(document);} catch (Exception e) {throw new RuntimeException(e);}}public void delete(String name){try {Document document = XMLUtils.document();NodeList nameList = document.getElementsByTagName("name");for(int i=0;i<nameList.getLength();i++){Node nameNode = nameList.item(i);if(nameNode.getTextContent().equals(name)){Node stuNode = nameNode.getParentNode();stuNode.getParentNode().removeChild(stuNode);XMLUtils.updateXML(document);return;}}throw new RuntimeException("-------对不起，你要删除的学生信息不存在!------");  //异常也是一种返回值。} catch (Exception e) {throw new RuntimeException(e);}}public Student find(String examid){Document document = null;try {document = XMLUtils.document();NodeList stuList = document.getElementsByTagName("student");Student student = null;for(int i=0;i<stuList.getLength();i++){Element stuNode = (Element)stuList.item(i);if(Integer.parseInt(stuNode.getAttribute("examid")) == Integer.parseInt(examid)){student = new Student();student.setName(stuNode.getElementsByTagName("name").item(0).getTextContent());student.setIdcard(stuNode.getAttribute("idcard"));student.setExamid(stuNode.getAttribute("examid"));student.setLocation(stuNode.getElementsByTagName("location").item(0).getTextContent());student.setGrade(Double.parseDouble(stuNode.getElementsByTagName("grade").item(0).getTextContent()));}}return student;} catch (Exception e) {throw new RuntimeException(e);}}}

Main.java

package cn.mengmei.main;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import cn.mengmei.dao.StudentDao;import cn.mengmei.domain.Student;public class Main {public static void main(String[] args) {System.out.println("添加用户：(a)    删除用户：(b)    查询成绩：(c)");System.out.print("请输入操作类型：");BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));String item = null;try {item = reader.readLine();} catch (IOException e1) {System.out.println("--------对不起，读取类型失败！--------");}String name = null;String idcard = null;String examid = null;String location = null;String grade = null;Student student = null;StudentDao dao = null;switch (item) {case "a":try {System.out.print("请输入学生姓名：");name = reader.readLine();System.out.print("请输入学生身份证号：");idcard = reader.readLine();System.out.print("请输入学生准考证号：");examid = reader.readLine();System.out.print("请输入学生所在地：");location = reader.readLine();System.out.print("请输入学生成绩：");grade = reader.readLine(); student = new Student();student.setName(name);student.setIdcard(idcard);student.setExamid(examid);student.setLocation(location);student.setGrade(Double.parseDouble(grade));dao = new StudentDao();dao.add(student);System.out.println("-----------添加数据成功-----------");} catch (Exception e) {System.out.println("-----------对不起，添加数据失败！-----------");}break;case "b":try {System.out.print("请输入要删除的学生姓名：");name = reader.readLine();dao = new StudentDao();dao.delete(name);System.out.println("------对已成功删除学生信息------");} catch (Exception e) {System.out.println(e.getMessage());}break;case "c":try {System.out.print("请输入要查询的学生准考证号：");examid = reader.readLine();dao = new StudentDao();student = dao.find(examid);if(student!=null){System.out.println("姓名："+student.getName());System.out.println("身份证号："+student.getIdcard());System.out.println("准考证号："+student.getExamid());System.out.println("所在地："+student.getLocation());System.out.println("成绩："+student.getGrade());}else{System.out.println("--------对不起，没有查询到此学生！-------");}} catch (Exception e) {System.out.println("------对不起，查询失败！------");}break;default:System.out.println("-------非法类型-------");break;}}}