学生管理小系统-XML DOM操作的实例小项目

叁歲伎倆 2022-05-20 00:53 238阅读 0赞

## 前言 ##

之前试了一下XML DOM操作,现在到了实际应用,自己写还是挺坎坷的,看看代码把

## 层次图 ##

![这里写图片描述][70]

*  dao Data Access Object 数据访问对象, 主要是访问数据用的
 *  domain 是model层,封装student类
 *  view 是视图层,和用户打交道的
 *  utils 是工具层,给dao层提供获得document对象,和写入xml文件的功能

看上去好像初步有了mvc模型,大体流程是这样的.  
用户在视图层调用view中的代码,比如查看的操作先发送给dao层,dao层从xml文件中读取数据，封装成Student模型，然后返回给用户，用户从模型中读取响应的数据，相对于增删改操作，用户不需要获得数据，就不需要经过Student模型,直接通过view操作dao层就行了.

## 设计顺序及代码 ##

先是Student层

package domain;
    
    public class Student { 
    
        private String idcard;
        private String examid;
        private String name;
        private String location;
        private int 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 int getGrade() {
            return grade;
        }
    
        public void setGrade(int grade) {
            this.grade = grade;
        }
    
        @Override
        public String toString() {
            return "Student{" +
                    "idcard='" + idcard + '\'' +
                    ", examid='" + examid + '\'' +
                    ", name='" + name + '\'' +
                    ", location='" + location + '\'' +
                    ", grade=" + grade +
                    '}';
        }
    }

下面是dao层

package dao;
    
    import domain.Student;
    import org.w3c.dom.Document;
    import org.w3c.dom.Element;
    import org.w3c.dom.Node;
    import org.w3c.dom.NodeList;
    import org.xml.sax.SAXException;
    import utils.XmlUtils;
    
    import javax.xml.parsers.ParserConfigurationException;
    import javax.xml.transform.TransformerException;
    import java.io.IOException;
    
    /** * <student idcard="111" examid="222"> * <name>张三</name> * <location>沈阳</location> * <grade>89</grade> * </student> */
    public class StudentDao {
    
        public void add(Student student) {
            try {
                Document document = XmlUtils.getDocument();
    
                Element student_element = document.createElement("student");
                student_element.setAttribute("idcard", student.getIdcard());
                student_element.setAttribute("examid", student.getExamid());
    
                Element name_element = document.createElement("name");
                name_element.setTextContent(student.getName());
    
                Element location_element = document.createElement("location");
                location_element.setTextContent(student.getLocation());
    
                Element grade_element = document.createElement("grade");
                grade_element.setTextContent(String.valueOf(student.getGrade()));
    
                student_element.appendChild(name_element);
                student_element.appendChild(location_element);
                student_element.appendChild(grade_element);
    
                document.getElementsByTagName("exam").item(0).appendChild(student_element);
    
                XmlUtils.write2Xml(document);
            } catch (ParserConfigurationException | IOException | SAXException | TransformerException e) {
                throw new RuntimeException(e);
            }
        }
    
        public Student find(String examid) {
            try {
                Document document = XmlUtils.getDocument();
                NodeList list = document.getElementsByTagName("student");
    
                for (int i = 0; i < list.getLength(); i++) { 
                    Node node = list.item(i);
                    if (node.getNodeType() == Node.ELEMENT_NODE) {
                        Element tmp = (Element) node;
                        if (tmp.getAttribute("examid").equals(examid)) {
                            return getStudent(tmp);
                        }
                    }
                }
    
            } catch (ParserConfigurationException | IOException | SAXException e) {
                e.printStackTrace();
            }
    
            return null;
        }
    
        public void delete(String name) {
            try {
                Document document = XmlUtils.getDocument();
                NodeList list = document.getElementsByTagName("student");
    
                for (int i = 0; i < list.getLength(); i++) { 
                    Node node = list.item(i);
                    if (node.getNodeType() == Node.ELEMENT_NODE) {
                        Element tmp = (Element) node;
                        if (tmp.getElementsByTagName("name").item(0).getTextContent().equals(name)) {
                            tmp.getParentNode().removeChild(tmp);
                            XmlUtils.write2Xml(document);
                            System.out.println("操作成功");
                            return;
                        }
                    }
                }
                System.out.println("删除学生失败,学生不存在");
            } catch (ParserConfigurationException | IOException | SAXException | TransformerException e) {
                e.printStackTrace();
            }
        }
    
        private Student getStudent(Element which) {
    
            if (which == null) {
                return null;
            }
    
            Student student = new Student();
    
            String idcard = which.getAttribute("idcard");
            String examid = which.getAttribute("examid");
            String name = which.getElementsByTagName("name").item(0).getTextContent();
            String location = which.getElementsByTagName("location").item(0).getTextContent();
            String grade = which.getElementsByTagName("grade").item(0).getTextContent();
    
            student.setName(name);
            student.setLocation(location);
            student.setIdcard(idcard);
            if (grade != null) {
                student.setGrade(Integer.parseInt(grade));
            }
            student.setExamid(examid);
    
            return student;
        }
    }

下面是工具层

package utils;
    
    import org.w3c.dom.Document;
    import org.xml.sax.SAXException;
    
    import javax.xml.parsers.DocumentBuilder;
    import javax.xml.parsers.DocumentBuilderFactory;
    import javax.xml.parsers.ParserConfigurationException;
    import javax.xml.transform.OutputKeys;
    import javax.xml.transform.Transformer;
    import javax.xml.transform.TransformerException;
    import javax.xml.transform.TransformerFactory;
    import javax.xml.transform.dom.DOMSource;
    import javax.xml.transform.stream.StreamResult;
    import java.io.File;
    import java.io.IOException;
    
    public class XmlUtils {
    
        public static Document getDocument() throws ParserConfigurationException, IOException, SAXException {
            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            DocumentBuilder builder = factory.newDocumentBuilder();
            return builder.parse(new File("src/student.xml"));
        }
    
        public static void write2Xml(Document document) throws TransformerException {
            TransformerFactory factory = TransformerFactory.newInstance();
            Transformer transformer = factory.newTransformer();
            transformer.setOutputProperty(OutputKeys.INDENT, "yes");
            transformer.transform(new DOMSource(document), new StreamResult(new File("src/student.xml")));
        }
    
    }

视图view

package view;
    
    import dao.StudentDao;
    import domain.Student;
    
    import java.util.Scanner;
    
    /** * <exam> * <student idcard="111" examid="222"> * <name>张三</name> * <location>沈阳</location> * <grade>89</grade> * </student> * </exam> */
    public class Main {
    
        public static void main(String[] args) {
            System.out.println("添加学生(a) 查找学生(b) 删除学生(c)");
            System.out.println("输入操作的类型");
    
            Scanner in = new Scanner(System.in);
            String type = in.nextLine();
    
            StudentDao dao = new StudentDao();
    
            if (type.equalsIgnoreCase("a")) {
                System.out.println("请输入学生姓名");
                String name = in.nextLine();
    
                System.out.println("请输入学生的学号");
                String idcard = in.nextLine();
    
                System.out.println("请输入学生的考试号");
                String examid = in.nextLine();
    
                System.out.println("请输入学生的成绩");
                String grade = in.nextLine();
    
                System.out.println("请输入学生的所在城市");
                String location = in.nextLine();
    
                Student student = new Student();
                student.setExamid(examid);
                student.setGrade(Integer.parseInt(grade));
                student.setIdcard(idcard);
                student.setLocation(location);
                student.setName(name);
    
                dao.add(student);
    
            } else if (type.equalsIgnoreCase("b")) {
                System.out.println("请输入学生的考试号");
                String examid = in.nextLine();
    
                Student student = dao.find(examid);
    
                if (student == null) {
                    System.out.println("学生未找到");
                } else {
                    System.out.println(student.toString());
                }
            } else if (type.equalsIgnoreCase("c")) {
                System.out.println("请输入学生的名字");
                String name = in.nextLine();
                dao.delete(name);
            }
    
        }
    
    }

## 结果 ##

初始xml文件:  
![这里写图片描述][70 1]

增加操作:  
![这里写图片描述][70 2]

![这里写图片描述][70 3]

查找操作:  
![这里写图片描述][70 4]

删除操作:  
![这里写图片描述][70 5]

![这里写图片描述][70 6]

## 总结 ##

算是自己的第一个java小项目把,实现的是xml的操作,写这些代码 用了得2个多小时把,从写完了之后,加入自己的想法,然后再整改代码,自己有一个思路,是在delete中使用find,但是问题出现的是document不一致,想到了用一个容器临时存入find中的document,来保证delete和find中的一致性,最后取得了成功,但是总感觉不太好.就换成了delete名字.若是你有什么想法,可以留言,我们一起看看呀~

[70]: /images/20220520/840aa422a10d47929bbb263dcc012856.png
[70 1]: /images/20220520/59ea0c24b74e4f2a8818e4a0965976b2.png
[70 2]: /images/20220520/b58ac1c3f6cb491699df61c50c55d72b.png
[70 3]: /images/20220520/c79771d098424274ab400bc3038284e2.png
[70 4]: /images/20220520/cd9bde6a0fad4882957c83301b1d2aa5.png
[70 5]: /images/20220520/d0eff6d906084bbd82952bb7c401fc74.png
[70 6]: /images/20220520/98fad4005dcb4f58b24badf8aee2cf76.png