1 package itacst.dao;  2   3 import org.w3c.dom.Document;  4 import org.w3c.dom.Element;  5 import org.w3c.dom.Node;  6 import org.w3c.dom.NodeList;  7   8 import itacst.domain.Student;  9 import itacst.exception.StudentNotExistException; 10 import itacst.utils.XmlUtils; 11  12 public class StudentDao { 13      14     public void add(Student s){ 15          16         try { 17             Document document = XmlUtils.getDocument(); 18              19             //创建出封装学生信息的标签 20             Element student_tag = document.createElement("student"); 21             student_tag.setAttribute("idcard", s.getIdcard()); 22             student_tag.setAttribute("examid", s.getExamid()); 23              24             //创建于封装学生姓名、所在地和成绩的标签 25             Element name = document.createElement("name"); 26             Element location = document.createElement("location"); 27             Element grade = document.createElement("grade"); 28              29             name.setTextContent(s.getName()); 30             location.setTextContent(s.getLocation()); 31             grade.setTextContent(s.getGrade()+"");//任意东西加上字符串就变成字符串 32              33             student_tag.appendChild(name); 34             student_tag.appendChild(location); 35             student_tag.appendChild(grade); 36              37             //把封装了信息学生标签，挂到文档上 38             document.getElementsByTagName("exam").item(0).appendChild(student_tag); 39              40             //更新内存 41             XmlUtils.write2Xml(document); 42              43         } catch (Exception e) { 44             throw new RuntimeException(e); 45             //unchecked excpeiton(运行时异常) 46         }//checked exception(编译时的异常 ) 47     } 48      49     public Student find(String examid){ 50          51         try { 52             Document document = XmlUtils.getDocument(); 53             NodeList list = document.getElementsByTagName("student"); 54              55             for (int i = 0; i < list.getLength(); i++) { 56                 Element student_tag = (Element) list.item(i); 57                 if(student_tag.getAttribute("examid").equals(examid)){ 58                     //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 59                     Student s = new Student(); 60                     s.setExamid(examid); 61                     s.setIdcard(student_tag.getAttribute("idcard")); 62                     s.setName(student_tag.getElementsByTagName("name").item(0).getTextContent()); 63                     s.setLocation(student_tag.getElementsByTagName("location").item(0).getTextContent()); 64                     s.setGrade(Double.parseDouble(student_tag.getElementsByTagName("grade").item(0).getTextContent())); 65                  66                     return s; 67                 } 68             } 69              70             return null; 71              72         } catch (Exception e) { 73             throw new RuntimeException(e); 74         } 75          76     } 77      78     public void delete(String name) throws StudentNotExistException{ 79          80         try { 81             Document document = XmlUtils.getDocument(); 82              83             NodeList list = document.getElementsByTagName("name"); 84              85             for (int i = 0; i < list.getLength(); i++) { 86                 if(list.item(i).getTextContent().equals(name)){ 87                     list.item(i).getParentNode().getParentNode().removeChild(list.item(i).getParentNode()); 88                     //更新内存 89                     XmlUtils.write2Xml(document); 90                     return; 91                 } 92             } 93              94              95              96             throw new StudentNotExistException(name+"not exist"); 97         }catch(StudentNotExistException e){ 98             throw e; 99         } catch (Exception e) {100             throw new RuntimeException(e);101         }102         103     }104 }

 1 package itacst.utils; 2  3 import java.io.FileOutputStream; 4  5 import javax.xml.parsers.DocumentBuilder; 6 import javax.xml.parsers.DocumentBuilderFactory; 7 import javax.xml.parsers.ParserConfigurationException; 8 import javax.xml.transform.Transformer; 9 import javax.xml.transform.TransformerConfigurationException;10 import javax.xml.transform.TransformerFactory;11 import javax.xml.transform.dom.DOMSource;12 import javax.xml.transform.stream.StreamResult;13 14 import org.w3c.dom.Document;15 16 public class XmlUtils {17     18     private static String filename="src/exam.xml";19     20     //获取xml21     public static Document getDocument() throws Exception{22         23         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();24         DocumentBuilder builder = factory.newDocumentBuilder();25         26         return builder.parse(filename);27     }28     29     //thinking in java30     public static void write2Xml(Document document) throws Exception{31         32         TransformerFactory factory = TransformerFactory.newInstance();33         Transformer tf = factory.newTransformer();34         tf.transform(new DOMSource(document), new StreamResult(new FileOutputStream(filename)));35     }36  37 }

 1 package itacst.test; 2  3 import org.junit.Test; 4  5 import itacst.dao.StudentDao; 6 import itacst.domain.Student; 7 import itacst.exception.StudentNotExistException; 8  9 public class StudentDaoTest {10     11     @Test12     public void testAdd(){13         StudentDao dao = new StudentDao();14         Student s = new Student();15         s.setExamid("121");16         s.setName("zero");17         s.setIdcard("121");18         s.setLocation("guangzhou");19         s.setGrade(89);20         dao.add(s);21     }22     23     @Test24     public void testFind(){25         StudentDao dao = new StudentDao();26         Student s = dao.find("121");27         28         System.out.println(s.getName()+s.getIdcard()+s.getExamid()+s.getLocation()+s.getGrade());29     }30     31     @Test32     public void testDelete() throws Exception{33         StudentDao dao = new StudentDao();34         dao.delete("zero");35     }36 37 }

 1 package itacst.domain; 2  3 public class Student { 4  5     private String idcard; 6     private String examid; 7     private String name; 8     private String location; 9     private double grade;10 11     public String getIdcard() {12         return idcard;13     }14 15     public void setIdcard(String idcard) {16         this.idcard = idcard;17     }18 19     public String getExamid() {20         return examid;21     }22 23     public void setExamid(String examid) {24         this.examid = examid;25     }26 27     public String getName() {28         return name;29     }30 31     public void setName(String name) {32         this.name = name;33     }34 35     public String getLocation() {36         return location;37     }38 39     public void setLocation(String location) {40         this.location = location;41     }42 43     public double getGrade() {44         return grade;45     }46 47     public void setGrade(double grade) {48         this.grade = grade;49     }50 }

 1 package itacst.UI; 2  3 import itacst.dao.StudentDao; 4 import itacst.domain.Student; 5 import itacst.exception.StudentNotExistException; 6  7 import java.io.BufferedReader; 8 import java.io.IOException; 9 import java.io.InputStreamReader;10 11 public class Main {12 13     /**14      * @param args15      * @throws IOException16      */17     public static void main(String[] args) {18         while(true){19         try {20             System.out.println("添加学生(a)    删除学生(b)     查询学生(c)");21             System.out.println("请输入操作类型：");22 23             BufferedReader br = new BufferedReader(new InputStreamReader(24                     System.in));25             String type = br.readLine();26             if ("a".equals(type)) {27 28                 System.out.print("请输入学生姓名：");29                 String name = br.readLine();30                 System.out.print("请输入学生准考证号：");31                 String examid = br.readLine();32                 System.out.print("请输入学生身份证号：");33                 String idcard = br.readLine();34                 System.out.print("请输入学生所在地：");35                 String location = br.readLine();36                 System.out.print("请输入学生成绩：");37                 String grade = br.readLine();38 39                 Student s = new Student();40                 s.setName(name);41                 s.setExamid(examid);42                 s.setIdcard(idcard);43                 s.setLocation(location);44                 s.setGrade(Double.parseDouble(grade));45 46                 StudentDao dao = new StudentDao();47                 dao.add(s);48 49                 System.out.println("添加成功");50 51             } else if ("b".equals(type)) {52 53                 System.out.print("请输入要删除的学生姓名：");54                 String name = br.readLine();55 56                 StudentDao dao = new StudentDao();57                 try {58                     dao.delete(name);59                     System.out.println("删除成功！");60                 } catch (StudentNotExistException e) {61 62                     e.printStackTrace();63                     System.out.println("your delete user not exist!!");64                 }65 66             } else if ("c".equals(type)) {67 68             } else {69                 System.out.println("unsupport your choice!!");70             }71 72         } catch (IOException e) {73 74             System.out.println("sorry error....");75         }76 77     }78     }79 80 }

 1 <?xml version="1.0" encoding="UTF-8" standalone="no"?><exam> 2     <student examid="222" idcard="111"> 3         <name>zhangsan</name> 4         <location>shenyang</location> 5         <grade>89</grade> 6     </student> 7     <student examid="444" idcard="333"> 8         <name>lisi</name> 9         <location>dalian</location>10         <grade>97</grade>11     </student>12     13     14  <student examid="321" idcard="321"><name>zero</name><location>guangzhou</location><grade>87.9</grade></student></exam>