JAVA初学练手项目，学生管理系统

github地址：https://github.com/qscqesze/StudentManager

简单描述一下：

UI层面用于接受用户的处理信息，然后移交给StudentDao去处理数据。

其中StudentDao通过修改Xml充当的数据库，来反馈数据。

StudentDomain是用来定义数据类型，Studentutils是处理数据时候封装的工具类型。

写了个额外的异常，Exception。

我也是参考着教程写的：《30天轻松掌握JavaWeb视频》 方立勋，网易云课堂里面有这个课程。

然后这个代码就结束了。

具体代码如下：

exam.xml //数据库文件

<?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</grade>
	</student>
	
	<student examid="444" idcard="333">
		<name>李四</name>
		<location>大连</location>
		<grade>97</grade>
	</student>
</exam>

StudentDaoTest.java //测试文件

package junit.test;

import org.junit.Test;

import en.itcast.dao.StudentDao;
import en.itcast.domain.Student;
import en.itcast.exception.StudentNotExistException;

public class StudentDaoTest {

	@Test
	public void testAdd(){
		StudentDao dao = new StudentDao();
		Student s = new Student();
		s.setExamid("121");
		s.setGrade(89);
		s.setIdcard("121");
		s.setLocation("北京");
		s.setName("aa");
		dao.add(s);
		
	}
	
	@Test
	public void testFind(){
		StudentDao dao = new StudentDao();
		dao.find("222");
	}

	@Test
	public void testdelete() throws StudentNotExistException{
		StudentDao dao = new StudentDao();
		dao.delete("aa");
	}
}

XmlUtils.java //工具类文件

package en.itcast.utils;

import java.io.FileOutputStream;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
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 {
	// 工具类约定俗成为静态类

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

	public static Document getDocument() throws Exception {
		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
		DocumentBuilder builder = factory.newDocumentBuilder();
		return builder.parse(filename);
	}

	// 编译异常就是垃圾
	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)));
		
	}
}

Main.java //主程序，ui界面的

package en.itcast.UI;

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

import en.itcast.dao.StudentDao;
import en.itcast.domain.Student;
import en.itcast.exception.StudentNotExistException;

public class Main {

	public static void main(String[] args) {
		System.out.println("添加用户(a) 删除用户(b) 查找用户(c)");
		System.out.print("请输入操作类型:");

		BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
		try {
			String type = bf.readLine();

			if ("a".equals(type)) {
				System.out.print("请输入学生姓名:");
				String name = bf.readLine();

				System.out.print("请输入学生准考证号:");
				String examid = bf.readLine();

				System.out.print("请输入学生所在地:");
				String location = bf.readLine();

				System.out.print("请输入学生身份证:");
				String idcard = bf.readLine();

				System.out.print("请输入学生成绩:");
				String grade = bf.readLine();

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

				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 = bf.readLine();
				try {
					StudentDao dao = new StudentDao();
					dao.delete(name);
					System.out.println("删除成功.");
				} catch (StudentNotExistException e) {
					System.out.println("你删除的用户不存在.");
				}

			} else if ("c".equals(type)) {
				System.out.print("请输入你要查询的准考证id:");
				String examid = bf.readLine();
				StudentDao dao = new StudentDao();
				Student find_student = dao.find(examid);
				if(find_student.equals(null)){
					System.out.println("对不起，找不到该学生.");
				}else{
					System.out.println("该学生的姓名是:"+find_student.getName());
				}
			} else {
				System.out.println("不支持你的操作");

			}
		} catch (IOException e) {
			e.printStackTrace();
			;
			System.out.println("sorry");
		}

	}

}

StudentNotExistException.java //自定义异常，处理删除的时候不存在用

package en.itcast.exception;

public class StudentNotExistException extends Exception {

	public StudentNotExistException() {
		// TODO Auto-generated constructor stub
	}

	public StudentNotExistException(String message) {
		super(message);
		// TODO Auto-generated constructor stub
	}

	public StudentNotExistException(Throwable cause) {
		super(cause);
		// TODO Auto-generated constructor stub
	}

	public StudentNotExistException(String message, Throwable cause) {
		super(message, cause);
		// TODO Auto-generated constructor stub
	}

	public StudentNotExistException(String message, Throwable cause, boolean enableSuppression,
			boolean writableStackTrace) {
		super(message, cause, enableSuppression, writableStackTrace);
		// TODO Auto-generated constructor stub
	}
	
}

Student.java //封装Student的数据类型

package en.itcast.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;
	}
	
}

StudentDao.java //程序处理

package en.itcast.dao;

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

import en.itcast.domain.Student;
import en.itcast.exception.StudentNotExistException;
import en.itcast.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());

			// 创建用于封装学生其他信息的标签
			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() + "");

			student_tag.appendChild(name);
			student_tag.appendChild(location);
			student_tag.appendChild(grade);
			// 把封装的信息挂在文档上
			document.getElementsByTagName("exam").item(0).appendChild(student_tag);

			XmlUtils.write2Xml(document);
		} catch (Exception 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++) {
				Element student_tag = (Element) list.item(i);
				if (student_tag.getAttribute("examid").equals(examid)) {
					// 找到匹配的学生了,new一个student对象
					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());
					XmlUtils.write2Xml(document);
					return;
				}
			}

			throw new StudentNotExistException(name + "不存在");

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

	}
}