【逻辑处理类StudentDao.java】
package com.heima.dao;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import com.heima.bean.Student;
import com.heima.util.JaxpUtils;
//业务逻辑处理类
public class StudentDao {
/**
* 将学生添加到XML文件中
* @param student 要添加的学生
* @return 成功返回TRUE，否则FALSE
*/
public boolean add(Student student){
//加载dom树
Document document = JaxpUtils.getDocument() ;
//拿到根节点
Element root = document.getDocumentElement() ;
//创建一个student节点,及子节点
Element stu = document.createElement("student") ;
Element nameEl = document.createElement("name") ;
Element locationEl = document.createElement("location") ;
Element gradeEl = document.createElement("grade") ;
//为student子节点和属性赋值
stu.setAttribute("examid", student.getExamid()) ;
stu.setAttribute("idcard", student.getIdcard()) ;
nameEl.setTextContent(student.getName()) ;
locationEl.setTextContent(student.getLocation()) ;
gradeEl.setTextContent(student.getGrade() + "") ;
//组合各个节点
stu.appendChild(nameEl) ;
stu.appendChild(locationEl) ;
stu.appendChild(gradeEl) ;
//将student节点添加到根节点上
root.appendChild(stu) ;
//将内存中的dom树保存到硬盘上
JaxpUtils.write2xml(document) ;
return true ;
}
/**
* 根据学生的姓名删除学生
* @param name 要删除学生的姓名
* @return 成功返回TRUE，否则返回FALSE
*/
public boolean delete(String name){
//加载dom树
Document document = JaxpUtils.getDocument() ;
//获取所有的name节点
NodeList nl = document.getElementsByTagName("name") ;
//循环判断
for (int i = 0; i < nl.getLength(); i++) {
Node n = nl.item(i) ;
if(n.getTextContent().equals(name)){
//说明找到了要删除的学生
//爷爷干掉父亲
n.getParentNode().getParentNode().removeChild(n.getParentNode()) ;
//将结果保存到硬盘上
JaxpUtils.write2xml(document) ;
return true ;
}
}
return false ;
}
/**
* 根据准考证号查询学生
* @param examid 要查询学生的准考证号
* @return 成功返回此学生，否则返回null
*/
public Student findByExamId(String examid){
//加载dom树
Document document = JaxpUtils.getDocument() ;
//拿取所有的学生节点
NodeList nl = document.getElementsByTagName("student") ;
//循环拿取每个student节点的examid属性的值判断
for (int i = 0; i < nl.getLength(); i++) {
Element stuNode = (Element)nl.item(i) ;
if(stuNode.getAttribute("examid").equals(examid)){
//找到了此学生
//开始封装数据
Student s = new Student() ;
s.setExamid(examid) ;
s.setIdcard(stuNode.getAttribute("idcard")) ;
s.setName(stuNode.getElementsByTagName("name").item(0).getTextContent()) ;
s.setLocation(stuNode.getElementsByTagName("location").item(0).getTextContent()) ;
s.setGrade(Float.parseFloat(stuNode.getElementsByTagName("grade").item(0).getTextContent())) ;
return s ;
}
}
return null ;
}
}

【学生类用来存储信息】
package com.jack.bean;
public class Student {
private String idcard;
public String getIdcard() {
return idcard;
}
public void setIdcard(String idcard) {
this.idcard = idcard;
}
@Override
public String toString() {
return "Student [idcard=" + idcard + ", examid=" + examid + ", name="
+ name + ", location=" + location + ", grade=" + grade + "]";
}
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 float getGrade() {
return grade;
}
public void setGrade(float grade) {
this.grade = grade;
}
private String examid;
private String name;
private String location;
private float grade;
}

【dom4j改造上面exam示列】
修改的类有StudentDom 类和JaxpUtils类剩下两个类，不许要改动，这是代码哦
【 JaxpUtils类】
package com.jack.util;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.UnsupportedEncodingException;
import org.dom4j.Document;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;
//工具类
public class JaxpUtils {
//用来获取dom树
public static Document getDocument() {
//创建dom4j解析器
try{
SAXReader reader = new SAXReader();
Document document = reader.read("src/exam.xml");
return document;
}catch(Exception e){
e.printStackTrace();
}
return null;
}
//保存树到硬盘
public static void write2xml(Document document){
try {
XMLWriter writer = new XMLWriter(new FileOutputStream("src/exam.xml"),OutputFormat.createPrettyPrint());
writer.write(document);
writer.close();//保存玩关闭流
} catch (Exception e) {
e.printStackTrace();
}
}
}
【StudentDom 类】
package com.jack.dao;
import java.util.List;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.Node;
import org.w3c.dom.NodeList;
import com.jack.bean.Student;
import com.jack.util.JaxpUtils;
/*
* 将学生添加到xml文件中
* student要添加的学生
* 成功返回true否则返回false
*/
//业务逻辑类
public class StudentDom {
public boolean add(Student student){
//首先加载dom树
Document document = JaxpUtils.getDocument();
//拿到根节点
Element root = document.getRootElement();
//创建一个students节点
Element stu = root.addElement("student").addAttribute("idcard", student.getIdcard())
.addAttribute("examid", student.getExamid());
//添加子节点
stu.addElement("name").setText(student.getName());
stu.addElement("location").setText(student.getLocation());
stu.addElement("grade").setText(student.getGrade()+"");
//将内存保存到硬盘
JaxpUtils.write2xml(document);
return true;
}
/*
* 根据学生姓名删除学生
*/
public boolean delete(String name){
//加载dom树
Document document = JaxpUtils.getDocument();
//获取根节点
Element root = document.getRootElement();
//拿到students节点
List<Element> stulist = root.elements("student");
//循环判断
for(int i = 0;i<stulist.size() ;i++){
Element stu = stulist.get(i);
if(stu.elementText("name").equals(name))
{
//找到了父亲干掉儿子
stu.getParent().remove(stu);
//保存结果
JaxpUtils.write2xml(document);
return true;
}
}
return false;
}
/*
*根据证考证号查询学生
*/
public Student findByExamId(String examid){
//加载dom树
Document document = JaxpUtils.getDocument();
//拿去根节点
Element root = document.getRootElement();
//拿去所有的学生节点
List<Element> stulist = root.elements("student");
//循环拿去每个stu接待你的examid熟悉进行判断
for(int i = 0;i<stulist.size();i++){
//找到这个学生了，开始封装了
Element stuNode = stulist.get(i);
if(stuNode.attributeValue("examid").equals(examid)){
Student s = new Student();
s.setExamid(examid);
s.setIdcard(stuNode.attributeValue("idcard"));
s.setName(stuNode.elementText("name"));
s.setLocation(stuNode.elementText("location"));
s.setGrade(Float.parseFloat(stuNode.elementText("grade")));
//保存
JaxpUtils.write2xml(document);
return s;
}
}
return null;
}
}

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