考试系统（用xml文件模拟数据库）

Posted 2021-11-26 vamps0911

1.界面介绍

2.系统结构介绍

我把各个包介绍一下

1.exam.xml文件就是用来模拟数据库的，代码在后面贴出来

2.dao层时操作数据包

3.utils是工具类包

4.bean是数据封装类包

5.exception是自定义异常类包

6.junit测试包

7.ui用户界面包

3.详细代码

1.exam.xml

 1 <?xml version="1.0" encoding="UTF-8" standalone="no"?><exam>
 2     <student examid="456" idcard="123">
 3         <name>a</name>
 4         <location>b</location>
 5         <grade>22</grade>
 6     </student>
 7     
 8     <student examid="000" idcard="789">
 9         <name>c</name>
10         <location>d</location>
11         <grade>20</grade>
12     </student>
13     
14     
15 </exam>

2.XmlUtils.java

 1 package utils;
 2 
 3 import java.io.FileOutputStream;
 4 
 5 import javax.xml.parsers.DocumentBuilder;
 6 import javax.xml.parsers.DocumentBuilderFactory;
 7 import javax.xml.transform.Transformer;
 8 import javax.xml.transform.TransformerFactory;
 9 import javax.xml.transform.dom.DOMSource;
10 import javax.xml.transform.stream.StreamResult;
11 
12 import org.w3c.dom.Document;
13 
14 //工具类的所有方法都是静态的（约定俗成）
15 public class XmlUtils {
16     
17     private static String filename = "src/exam.xml";
18     
19     public static Document getDocument() throws Exception{
20         
21         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
22         DocumentBuilder builder = factory.newDocumentBuilder();
23         return builder.parse(filename);
24         
25     }
26     
27     public static void write2Xml(Document document) throws Exception{
28         
29         TransformerFactory factory = TransformerFactory.newInstance();
30         Transformer tf = factory.newTransformer();
31         tf.transform(new DOMSource(document), new StreamResult(new FileOutputStream(filename)));
32         
33     }
34     
35 }

getDocument()方法用来获取标签对象

write2Xml(Document document)方法用来更新xml文件

3.StudentDao.java

 1 package dao;
 2 
 3 import org.w3c.dom.Document;
 4 import org.w3c.dom.Element;
 5 import org.w3c.dom.NodeList;
 6 
 7 import bean.Student;
 8 import exception.StudentNotExistException;
 9 import utils.XmlUtils;
10 
11 public class StudentDao {
12     
13     public void add(Student s){
14         
15         try {
16             Document document = XmlUtils.getDocument();
17             
18             //创建出封装学生的标签
19             Element student_tag = document.createElement("student");
20             student_tag.setAttribute("idcard", s.getIdcard());
21             student_tag.setAttribute("examid", s.getExamid());
22             
23             //创建用于封装学生姓名，所在地和成绩的标签
24             Element name = document.createElement("name");
25             Element location = document.createElement("location");
26             Element grade = document.createElement("grade");
27             name.setTextContent(s.getName());
28             location.setTextContent(s.getIdcard());
29             grade.setTextContent(s.getGrade()+"");
30             
31             //设置标签之间的关系
32             student_tag.appendChild(name);
33             student_tag.appendChild(location);
34             student_tag.appendChild(grade);
35             
36             //把封装信息的学生标签，要挂在文档上面
37             document.getElementsByTagName("exam").item(0).appendChild(student_tag);
38             
39             //更新内存
40             XmlUtils.write2Xml(document);
41             
42         } catch (Exception e) {
43             //把异常进行转型，把编译时异常转化成运行时异常
44             throw new RuntimeException(e);
45         }
46         
47         
48     }
49     
50     public Student find(String examid){
51         
52         try {
53             Document document = XmlUtils.getDocument();
54             NodeList list = document.getElementsByTagName("student");
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相对应的学生，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                     return s;
66                 }
67             }
68             return null;
69         } catch (Exception e) {
70             // TODO Auto-generated catch block
71             throw new RuntimeException(e);
72         }
73     }
74     
75     public void delete(String name) throws StudentNotExistException{
76         
77         try {
78             Document document = XmlUtils.getDocument();
79             NodeList list = document.getElementsByTagName("name");
80             for(int i=0; i<list.getLength(); i++){
81                 if(list.item(i).getTextContent().equals(name)){
82                     list.item(i).getParentNode().getParentNode().removeChild(list.item(i).getParentNode());
83                     XmlUtils.write2Xml(document);
84                     return;
85                 }
86             }
87             throw new StudentNotExistException(name + "不存在！");
88         }catch(StudentNotExistException e){
89             throw e;
90         }catch (Exception e) {
91             // TODO Auto-generated catch block
92             throw new RuntimeException();
93         }
94         
95     }
96     
97 }

4.student.java

 

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

5.StudentNotExistException.java

 1 package exception;
 2 
 3 public class StudentNotExistException extends Exception {
 4 
 5     public StudentNotExistException() {
 6         // TODO Auto-generated constructor stub
 7     }
 8 
 9     public StudentNotExistException(String message) {
10         super(message);
11         // TODO Auto-generated constructor stub
12     }
13 
14     public StudentNotExistException(Throwable cause) {
15         super(cause);
16         // TODO Auto-generated constructor stub
17     }
18 
19     public StudentNotExistException(String message, Throwable cause) {
20         super(message, cause);
21         // TODO Auto-generated constructor stub
22     }
23 
24     public StudentNotExistException(String message, Throwable cause, boolean enableSuppression,
25             boolean writableStackTrace) {
26         super(message, cause, enableSuppression, writableStackTrace);
27         // TODO Auto-generated constructor stub
28     }
29 
30 }

6.Main.java

 1 package ui;
 2 
 3 import java.io.BufferedReader;
 4 import java.io.InputStreamReader;
 5 
 6 import bean.Student;
 7 import dao.StudentDao;
 8 import exception.StudentNotExistException;
 9 
10 public class Main {
11 
12     public static void main(String[] args) {
13         // TODO Auto-generated method stub
14         try{
15             System.out.println("添加学生：（a）   删除学生（b）   查找学生（c）   退出（e）");
16             System.out.print("请输入操作类型：");
17             BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
18             String type = br.readLine(); 
19             //switch不能用String
20             if("a".equals(type)){
21                 
22                 System.out.println("请输入学生姓名：");
23                 String name = br.readLine();
24                 
25                 System.out.println("请输入学生准考证号：");
26                 String examid = br.readLine();
27                 
28                 System.out.println("请输入学生身份证号：");
29                 String idcard = br.readLine();
30                 
31                 System.out.println("请输入学生所在地：");
32                 String location = br.readLine();
33                 
34                 System.out.println("请输入学生成绩：");
35                 String grade = br.readLine();
36                 
37                 Student s = new Student();
38                 s.setExamid(examid);
39                 s.setGrade(Double.parseDouble(grade));
40                 s.setIdcard(idcard);
41                 s.setName(name);
42                 s.setLocation(location);
43                 
44                 StudentDao dao = new StudentDao();
45                 dao.add(s);
46                 System.out.println("添加成功");
47                 
48             }else if("b".equals(type)){
49                 
50                 System.out.print("请输入要删除学生的姓名：");
51                 String name = br.readLine();
52                 try{
53                     StudentDao dao = new StudentDao();
54                     dao.delete(name);
55                     System.out.println("删除成功！");
56                 }catch(StudentNotExistException e){
57                     System.out.println("此学生不存在！");
58                 }
59                 
60             }else if("c".equals(type)){
61                 
62                 System.out.println("请输入要查找用户的准考证号");
63                 String examid = br.readLine();
64                 StudentDao dao = new StudentDao();
65                 Student s = dao.find(examid);
66                 System.out.println(s);
67                 
68             }else if("e".equals(type)){
69                 
70                 System.out.println("退出成功！");
71                 return;
72                 
73             }else{
74                 System.out.println("不支持你的操作！");
75             }
76         }catch(Exception e){
77             e.printStackTrace();
78             System.out.println("对不起，出错误了");
79         }
80     }
81 
82 }