package dao;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import utils.XMLUtils;
import domain.Student;
public class StudentDao {
/**
* 添加学生信息模块
* @param student
*/
public void add(Student student) {
try {
Document document = XMLUtils.getDocument();
Element student_node = document.createElement("student");
student_node.setAttribute("examid", student.getExamid());
student_node.setAttribute("idcard", student.getIdcard());
Element name = document.createElement("name");
name.setTextContent(student.getName());
Element location = document.createElement("location");
location.setTextContent(student.getLocation());
Element grade = document.createElement("grade");
// 这里是一个类型转换的隐藏之处。不太明显但是却十分的重要
grade.setTextContent(student.getGrade() + "");
// 将新生成的三个子节点插入到student标签内
student_node.appendChild(name);
student_node.appendChild(location);
student_node.appendChild(grade);
// 对总的xml文档中添加一个学生信息
document.getElementsByTagName("exam").item(0)
.appendChild(student_node);
//将内存中的操作对象写回到xml文件，真正实现对文件的操作
XMLUtils.write2Xml(document);
} catch (Exception e) {
// TODO Auto-generated catch block
throw new RuntimeException(e);
}
}
public void delete(String name) {
try {
Document document = XMLUtils.getDocument();
NodeList name_node_list = document.getElementsByTagName("name");
for (int i = 0; i < name_node_list.getLength(); i++) {
if (name_node_list.item(i).getTextContent().equals(name)) {
Element person_node = (Element) name_node_list.item(i)
.getParentNode();
Element exam_node = (Element) person_node.getParentNode();
exam_node.removeChild(person_node);
//不要忘记将操作过的数据写回，否则原信息是不会发生变化的
XMLUtils.write2Xml(document);
System.out.println("恭喜，学生信息删除成功！");
}
}
} catch (Exception e) {
System.out.println("对不起，删除操作未成功完成！请重试！");
throw new RuntimeException(e);
}
}
/**
* 给定学生的考号查找该同学的详细的信息（不用姓名的原因是姓名具有不唯一性）
* @param examid
* @return
*/
public Student find(String examid) {
Student student=null;
try {
Document document = XMLUtils.getDocument();
NodeList examid_node_list = document.getElementsByTagName("student");
//查找准考证号与查找值相一致的学生节点
for(int i=0; i<examid_node_list.getLength();i++){
Element examid_element = (Element) examid_node_list.item(i);
if(examid_element.getAttribute("examid").equals(examid.toString().trim())){
//采用非递归的方式获取student的详细信息
student = getStudentInfo(examid_element);
return student;
}else{
continue;
}
}
} catch (Exception e) {
e.printStackTrace();
System.out.println("对不起，未能正确的找到您要查找的学生的姓名！请确认后重新尝试！");
}
return student;
}
/**
* 给定一个节点，采用非递归的方式遍历该学生节点的详细的信息
* 缺点：不能很好地复用代码，代码维护性较差
*/
public Student getStudentInfo(Element node){
Student student = new Student();
if(node!=null){
String examid = node.getAttribute("examid");
String idcard = node.getAttribute("idcard");
NodeList node_list = node.getChildNodes();
//由于collection 的不确定性，是随机取出的数据，导致bean中的数据不太对应
Node node_name = node_list.item(1);
String name = node_name.getTextContent();
Node node_location = node_list.item(2);
String location = node_location.getTextContent();
Node node_grade = node_list.item(0);
String grade = node_grade.getTextContent()+"0.0";
//将获取的信息保存到bean中，并作为返回值返回！
student.setExamid(examid);
student.setGrade(Double.parseDouble(grade));
student.setIdcard(idcard);
student.setLocation(location);
student.setName(name);
return student;
}
System.out.println("this find operation is false!");
return null;
}
}
StudentSystem.rar （13个子文件） 
StudentSystem bin 
Student.xml 604B dao StudentDao.class 4KB domain Student.class 1KB view Main.class 3KB utils XMLUtils.class 2KB .settings org.eclipse.jdt.core.prefs 598B src Student.xml 604B dao StudentDao.java 4KB domain Student.java 776B view Main.java 2KB utils XMLUtils.java 1KB .project 389B .classpath 301B 新建文件夹 资源评论
