以如下格式的exam.xml文件为例
<?xml version="1.0" encoding="UTF-8" standalone="no"?> <exam> <student idcard="111" examid="222"> <name>张三</name> <location>沈阳</location> <grade>89</grade> </student> <student idcard="333" examid="444"> <name>李四</name> <location>大连</location> <grade>97</grade> </student> </exam>
编程实现如下功能
添加用户的界面如下：
删除用户的界面如下：
查询用户的界面如下：
用JAXP DOM方式完成：
把功能分层设计，好处多多，分层图分析如下：
分层图功能说明：
增：用户通过界面输入学生数据，程序接收后通过JavaBean的设置方法封装成JavaBean对象，并传给DAO，DAO通过JavaBean的获取方法获取传过来的JavaBean学生信息，经过处理后写入XML；
查：用户通过界面输入要查询的学生姓名，并传给DAO，DAO通过XML获取符合要求的学生信息，并通过JavaBean的设置方法封装成JavaBean，再传给Main，然后Main通过JavaBean的获取方法取出学生信息。
删：用户通过界面输入要删除的学生的准考证号，并传给DAO，DAO删除XML中符合要求的学生
根据分层设计图创建如下包和类：
1、com.itheima.domain包： Student.java （JavaBean）
2、com.itheima.util包：JaxpUtil.java （getDocument()、write2xml()方法，用于获取DOM树对象和把DOM树对象写入XML文件）
3、com.itheima.dao包：StudentDaoImpl.java （学生DAO实现类，方法：addStudent() ，queryStudent()，deleteStudent()，即增、查、删三个方法）
4、com.itheima.test包：StudentDaoImplTest.java（用于临时测试StudentDaoImpl.java里面的增、查、删方法）
5、com.itheima.view包：Main.java（用于编写用户界面，接收用户信息）
具体代码如下：
1、com.itheima.domain包： Student.java
package com.itheima.domain;
public class Student {
private String idcard;
private String examid;
private String name;
private String location;
private float 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 float getGrade() {
return grade;
}
public void setGrade(float grade) {
this.grade = grade;
}
@Override
public String toString() {
return "Student [idcard=" + idcard + ", examid=" + examid + ", name="
+ name + ", location=" + location + ", grade=" + grade + "]";
}
}
2、com.itheima.util包：JaxpUtil.java
package com.itheima.util;
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 JaxpUtil {
public static Document getDocument() throws Exception{
DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document document = db.parse("src/exam.xml");
return document;
}
public static void write2xml(Document document) throws Exception {
Transformer t = TransformerFactory.newInstance().newTransformer();
t.transform(new DOMSource(document), new StreamResult("src/exam.xml"));
}
}
3、com.itheima.dao包：StudentDaoImpl.java
package com.itheima.dao;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import com.itheima.domain.Student;
import com.itheima.util.JaxpUtil;
public class StudentDaoImpl {
public static boolean addStudent(Student student){
boolean result = false;
try{
//1、获取DOM树
Document document = JaxpUtil.getDocument();
//2、创建学生元素,并添加属性或主体内容
Element studentE = document.createElement("student");
studentE.setAttribute("idcard", student.getIdcard());
studentE.setAttribute("examid", student.getExamid());
Element nameE = document.createElement("name");
nameE.setTextContent(student.getName());
Element locationE = document.createElement("location");
locationE.setTextContent(student.getLocation());
Element gradeE = document.createElement("grade");
gradeE.setTextContent(student.getGrade()+"");
//3、把学生元素添加到DOM
Node examN = document.getElementsByTagName("exam").item(0);
examN.appendChild(studentE);
studentE.appendChild(nameE);
studentE.appendChild(locationE);
studentE.appendChild(gradeE);
//4、把DOM树写回XML文档中
JaxpUtil.write2xml(document);
result = true;
}catch(Exception e){
throw new RuntimeException(e);
}
return result;
}
public static Student queryStudent(String examid){
Student student = null;
//1、获得DOM树
Document document;
try {
document = JaxpUtil.getDocument();
} catch (Exception e) {
throw new RuntimeException(e);
}
//2、获得所有student节点，遍历这些节点的examid属性，
//以便找到要查找的examid，并获得这个属性的studetn节点
NodeList studentNodeList = document.getElementsByTagName("student");
Element studentE = null;
for(int i=0;i<studentNodeList.getLength();i++){
studentE = (Element) studentNodeList.item(i);
if(studentE.getAttribute("examid").equals(examid))
break;//此时的studentE就是要查找的目标
}
//3、把打到的studentE的所有属性值/节点的主体内容封装成StudentBean并返回
student = new Student();
student.setExamid(studentE.getAttribute(examid));
student.setIdcard(studentE.getAttribute("idcard"));
student.setName(studentE.getElementsByTagName("name").item(0).getTextContent());
student.setLocation(studentE.getElementsByTagName("location").item(0).getTextContent());
student.setGrade(Float.parseFloat(studentE.getElementsByTagName("grade").item(0).getTextContent()));
return student;
}
public static boolean deleteStudent(String name){
boolean result = false;
//1、获得DOM树
Document document;
try {
document = JaxpUtil.getDocument();
} catch (Exception e) {
throw new RuntimeException(e);
}
//2、获得所有的name列表，并遍历找到需要的name节点并删除name的父节点(student)
NodeList nameNodeList = document.getElementsByTagName("name");
for(int i=0;i<nameNodeList.getLength();i++){
if(nameNodeList.item(i).getTextContent().equals(name)){
nameNodeList.item(i).getParentNode().getParentNode().
removeChild(nameNodeList.item(i).getParentNode());
result = true;
break;
}
}
//3、把删除节点后的DOM树写回XML文档
try {
JaxpUtil.write2xml(document);
} catch (Exception e) {
throw new RuntimeException(e);
}
return result;
}
}
4、com.itheima.test包：StudentDaoImplTest.java
package com.itheima.test;
import com.itheima.dao.StudentDaoImpl;
import com.itheima.domain.Student;
public class StudentDaoImplTest {
public static void main(String[] args) {
/*Student student = new Student();
student.setIdcard("3838438");
student.setExamid("520");
student.setName("阿Q");
student.setLocation("地球");
student.setGrade(99.5f);
StudentDaoImpl.addStudent(student);*//测试添加功能
Student student = StudentDaoImpl.queryStudent("444");//测试查询功能
if(!(student == null))
System.out.println(student.getName());
else
System.out.println("没有这个人！");
StudentDaoImpl.deleteStudent("阿Q");//测试删除功能
}
}
5、com.itheima.view包：Main.java
package com.itheima.view;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import com.itheima.dao.StudentDaoImpl;
import com.itheima.domain.Student;
public class Main {
public static void main(String[] args) {
System.out.println("a)添加用户：\tb)查询用户：" +
"\tc)删除用户：\n请输入操作类型：");
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
try {
String line = reader.readLine();
if(line.equals("a")){
System.out.println("请输入学生姓名：");
String name = reader.readLine();
System.out.println("请输入学生准考证号：");
String examid = reader.readLine();
System.out.println("请输入学生身份证号：");
String idcard = reader.readLine();
System.out.println("请输入学生所在地：");
String location = reader.readLine();
System.out.println("请输入学生成绩：");
String grade = reader.readLine();
//添加学生JavaBean对象
Student student = new Student();
student.setName(name);
student.setExamid(examid);
student.setIdcard(idcard);
student.setLocation(location);
student.setGrade(Float.parseFloat(grade));
//将学生JavaBean对象信息添加到XML文件中
if(StudentDaoImpl.addStudent(student))
System.out.println("恭喜，添加成功！");
else
System.out.println("对不起，服务器忙！");
}else if(line.equals("b")){
System.out.println("请输入查询的学生准考证号：");
String examid = reader.readLine();
Student student = StudentDaoImpl.queryStudent(examid);
if(student != null)
System.out.println("您查询学生的信息为：\n" + student);
else
System.out.println("对不起，服务器忙！");
}else if(line.endsWith("c")){
System.out.println("请输入要删除的学生姓名：");
String name = reader.readLine();
if(StudentDaoImpl.deleteStudent(name))
System.out.println("已成功删除学生信息！");
else
System.out.println("您输入的学生不存在！");
}else
System.out.println("输入错误，请重新输入");
} catch (IOException e) {
System.out.println("不好意思，服务器忙！");
}
}
}