xml案例(考生成绩管理系统)

 package itacst.dao;

 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.w3c.dom.Node;
 import org.w3c.dom.NodeList;

 import itacst.domain.Student;
 import itacst.exception.StudentNotExistException;
 import itacst.utils.XmlUtils;

 public class StudentDao {

     public void add(Student s){

         try {
             Document document = XmlUtils.getDocument();

             //创建出封装学生信息的标签
             Element student_tag = document.createElement("student");
             student_tag.setAttribute("idcard", s.getIdcard());
             student_tag.setAttribute("examid", s.getExamid());

             //创建于封装学生姓名、所在地和成绩的标签
             Element name = document.createElement("name");
             Element location = document.createElement("location");
             Element grade = document.createElement("grade");

             name.setTextContent(s.getName());
             location.setTextContent(s.getLocation());
             grade.setTextContent(s.getGrade()+"");//任意东西加上字符串就变成字符串

             student_tag.appendChild(name);
             student_tag.appendChild(location);
             student_tag.appendChild(grade);

             //把封装了信息学生标签，挂到文档上
             document.getElementsByTagName("exam").item(0).appendChild(student_tag);

             //更新内存
             XmlUtils.write2Xml(document);

         } catch (Exception e) {
             throw new RuntimeException(e);
             //unchecked excpeiton(运行时异常)
         }//checked exception(编译时的异常 )
     }

     public Student find(String examid){

         try {
             Document document = XmlUtils.getDocument();
             NodeList list = document.getElementsByTagName("student");

             for (int i = 0; i < list.getLength(); i++) {
                 Element student_tag = (Element) list.item(i);
                 if(student_tag.getAttribute("examid").equals(examid)){
                     //找到与examid相匹配的学生，new出一个student对象封装这个学生的信息返回
                     Student s = new Student();
                     s.setExamid(examid);
                     s.setIdcard(student_tag.getAttribute("idcard"));
                     s.setName(student_tag.getElementsByTagName("name").item(0).getTextContent());
                     s.setLocation(student_tag.getElementsByTagName("location").item(0).getTextContent());
                     s.setGrade(Double.parseDouble(student_tag.getElementsByTagName("grade").item(0).getTextContent()));

                     return s;
                 }
             }

             return null;

         } catch (Exception e) {
             throw new RuntimeException(e);
         }

     }

     public void delete(String name) throws StudentNotExistException{

         try {
             Document document = XmlUtils.getDocument();

             NodeList list = document.getElementsByTagName("name");

             for (int i = 0; i < list.getLength(); i++) {
                 if(list.item(i).getTextContent().equals(name)){
                     list.item(i).getParentNode().getParentNode().removeChild(list.item(i).getParentNode());
                     //更新内存
                     XmlUtils.write2Xml(document);
                     return;
                 }
             }

             throw new StudentNotExistException(name+"not exist");
         }catch(StudentNotExistException e){
             throw e;
         } catch (Exception e) {
             throw new RuntimeException(e);
         }

     }
 }

 package itacst.utils;

 import java.io.FileOutputStream;

 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
 import javax.xml.parsers.ParserConfigurationException;
 import javax.xml.transform.Transformer;
 import javax.xml.transform.TransformerConfigurationException;
 import javax.xml.transform.TransformerFactory;
 import javax.xml.transform.dom.DOMSource;
 import javax.xml.transform.stream.StreamResult;

 import org.w3c.dom.Document;

 public class XmlUtils {

     private static String filename="src/exam.xml";

     //获取xml
     public static Document getDocument() throws Exception{

         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
         DocumentBuilder builder = factory.newDocumentBuilder();

         return builder.parse(filename);
     }

     //thinking in java
     public static void write2Xml(Document document) throws Exception{

         TransformerFactory factory = TransformerFactory.newInstance();
         Transformer tf = factory.newTransformer();
         tf.transform(new DOMSource(document), new StreamResult(new FileOutputStream(filename)));
     }

 }

 package itacst.test;

 import org.junit.Test;

 import itacst.dao.StudentDao;
 import itacst.domain.Student;
 import itacst.exception.StudentNotExistException;

 public class StudentDaoTest {

     @Test
     public void testAdd(){
         StudentDao dao = new StudentDao();
         Student s = new Student();
         s.setExamid("121");
         s.setName("zero");
         s.setIdcard("121");
         s.setLocation("guangzhou");
         s.setGrade(89);
         dao.add(s);
     }

     @Test
     public void testFind(){
         StudentDao dao = new StudentDao();
         Student s = dao.find("121");

         System.out.println(s.getName()+s.getIdcard()+s.getExamid()+s.getLocation()+s.getGrade());
     }

     @Test
     public void testDelete() throws Exception{
         StudentDao dao = new StudentDao();
         dao.delete("zero");
     }

 }

 package itacst.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;
     }
 }

 package itacst.UI;

 import itacst.dao.StudentDao;
 import itacst.domain.Student;
 import itacst.exception.StudentNotExistException;

 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStreamReader;

 public class Main {

     /**
      * @param args
      * @throws IOException
      */
     public static void main(String[] args) {
         while(true){
         try {
             System.out.println("添加学生(a)    删除学生(b)     查询学生(c)");
             System.out.println("请输入操作类型：");

             BufferedReader br = new BufferedReader(new InputStreamReader(
                     System.in));
             String type = br.readLine();
             if ("a".equals(type)) {

                 System.out.print("请输入学生姓名：");
                 String name = br.readLine();
                 System.out.print("请输入学生准考证号：");
                 String examid = br.readLine();
                 System.out.print("请输入学生身份证号：");
                 String idcard = br.readLine();
                 System.out.print("请输入学生所在地：");
                 String location = br.readLine();
                 System.out.print("请输入学生成绩：");
                 String grade = br.readLine();

                 Student s = new Student();
                 s.setName(name);
                 s.setExamid(examid);
                 s.setIdcard(idcard);
                 s.setLocation(location);
                 s.setGrade(Double.parseDouble(grade));

                 StudentDao dao = new StudentDao();
                 dao.add(s);

                 System.out.println("添加成功");

             } else if ("b".equals(type)) {

                 System.out.print("请输入要删除的学生姓名：");
                 String name = br.readLine();

                 StudentDao dao = new StudentDao();
                 try {
                     dao.delete(name);
                     System.out.println("删除成功！");
                 } catch (StudentNotExistException e) {

                     e.printStackTrace();
                     System.out.println("your delete user not exist!!");
                 }

             } else if ("c".equals(type)) {

             } else {
                 System.out.println("unsupport your choice!!");
             }

         } catch (IOException e) {

             System.out.println("sorry error....");
         }

     }
     }

 }

 <?xml version="1.0" encoding="UTF-8" standalone="no"?><exam>
     <student examid="222" idcard="111">
         <name>zhangsan</name>
         <location>shenyang</location>
         <grade>89</grade>
     </student>
     <student examid="444" idcard="333">
         <name>lisi</name>
         <location>dalian</location>
         <grade>97</grade>
     </student>

  <student examid="321" idcard="321"><name>zero</name><location>guangzhou</location><grade>87.9</grade></student></exam>