DOM4J案例详解(添加 ,查询 ,删除 ,保存)

先看一下XML文档

<?xml version="1.0" encoding="gb2312"?>
<exam>
  <student idcard="111" examid="222">
    <name>张三</name>
    <location>深圳</location>
    <score>89</score>
  </student>
  <student idcard="777" examid="666">
    <name>李四</name>
    <location>上海</location>
    <score>99</score>
  </student>
</exam>

主要是对此文档读取,添加,删除,保存(刷新)等处理实现下面的功能

首先要建立一个学生的实体类

 public class Student {
     private String name;
     private String examid;//准考证号
     private String idcard;//身份证号
     private String location;//地址
     private String score; //分数

     public Student(){    //无参构造
     }

     public Student(String name, String examid, String idcard, String location,
             String score) {            //有参构造
         super();
         this.name = name;
         this.examid = examid;
         this.idcard = idcard;
         this.location = location;
         this.score = score;
     }
     //下面是set get 方法
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
     public String getExamid() {
         return examid;
     }
     public void setExamid(String examid) {
         this.examid = examid;
     }
     public String getIdcard() {
         return idcard;
     }
     public void setIdcard(String idcard) {
         this.idcard = idcard;
     }
     public String getLocation() {
         return location;
     }
     public void setLocation(String location) {
         this.location = location;
     }
     public String getScore() {
         return score;
     }
     public void setScore(String score) {
         this.score = score;
     }

 }//类的

然后建立一个接口类,里面添加的方法分别是(添加,删除,读取)

 public interface AddStu {
     /**
      * 添加学生
      */
     public boolean addStudent(Student stu);
     /**
      * 删除学生
      */
     public boolean removeStudent(String name);
     /**
      * 查询学生
      */
     public Student caxunStudent(String examid);
 }

然后是实现接口的类

 public class AddStuimpl implements AddStu{

     @Override
     public boolean addStudent(Student stu) {
         boolean flay=false;
         Document dom=null;
         //1.创建解析器
         SAXReader reader = new SAXReader();
         //2.解析文档
          try {
             dom = reader.read(new File("src/student.xml"));
             Element rootElement=dom.getRootElement();
             //添加元素
             Element stuEle=rootElement.addElement("student");
             stuEle.addAttribute("idcard", stu.getIdcard());
             stuEle.addAttribute("examid", stu.getExamid());
             //添加子节点
             stuEle.addElement("name").setText(stu.getName());
             stuEle.addElement("location").setText(stu.getLocation());
             stuEle.addElement("score").setText(stu.getScore());
             //更新XML  (保存信息)
             OutputFormat of=OutputFormat.createPrettyPrint();//格式化器
             of.setEncoding("gb2312");
             XMLWriter xw=new XMLWriter(new FileWriter("src/student.xml"),of);
             xw.write(dom);
             xw.close();

             flay=true;
         } catch (Exception e) {
             e.printStackTrace();
         }

         return flay;

     }

     @Override
     public boolean removeStudent(String name) {
         boolean flay=false;
         Document dom=null;
         //1.创建解析器
         SAXReader reader = new SAXReader();
         //2.解析文档

             try {
                 dom = reader.read(new File("src/student.xml"));
                 Element root=dom.getRootElement(); //获取根节点
                 List<Element> list=root.elements("student"); //选择要对哪个元素进行操作
                 for (Element e : list) {
                     Element nameEle=e.element("name");
                     if(nameEle.getText().equals(name)){
                         root.remove(e);
                         flay=true;
                     }

                 }
                 //更新
                 OutputFormat of=OutputFormat.createPrettyPrint();//格式化器
                 of.setEncoding("gb2312");
                 XMLWriter xw=new XMLWriter(new FileWriter("src/student.xml"),of);
                 xw.write(dom);
                 xw.close();

             } catch (DocumentException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             } catch (IOException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }

         return flay;
     }

     @Override
     public Student caxunStudent(String examid) {
         Student s=null;
         Document dom=null;
         //1.创建解析器
         SAXReader reader = new SAXReader();
         //2.解析文档
          try {
             dom = reader.read(new File("src/student.xml"));
             Element root=dom.getRootElement(); //获取根节点
             List<Element> list=root.elements("student");
             Element ele=null;
             for (Element e : list) {
                 String str2=e.attribute("examid").getText();
                 //String str2=e.attributeValue("examid");  与上一条意思一样
                 if(str2.equals(examid)){
                     ele=e;
                     break;
                 }
             }
             if(ele!=null){
                 String name=ele.elementText("name");
                 String location=ele.element("location").getText();
                 String score=ele.elementText("score");
                 String idcard=ele.attributeValue("idcard");
                 String examid1=ele.attributeValue("examid");
                 s=new Student(name, examid1, idcard, location, score);
             }
                 } catch (DocumentException e) {

                     e.printStackTrace();
                 }
         return s;
     }

 }

最后则是测试类及对添加等方法的测试

 /**
  * 测试
  * 2017-5-3
  *下午2:40:47
  */
 public class StudentBiz {
     //static Student stu=new Student();
     static Scanner input=new Scanner(System.in);
     static AddStuimpl asi=new AddStuimpl();
     public static void main(String[] args) {
         System.out.println("添加学生(1)\t删除学生(2)\t查询成绩(3)\t退出(4)");
         do{
         System.out.print("请选择有效序号: ");
         int a=input.nextInt();
         switch(a){
         case 1:
             System.out.println("请输入学生的姓名");
             String name=input.next();
             System.out.println("请输入学生的准考证号");
             String examid=input.next();
             System.out.println("请输入学生的身份证号");
             String idcard=input.next();
             System.out.println("请输入学生的所在地");
             String location=input.next();
             System.out.println("请输入学生的成绩");
             String score=input.next();
             Student stu=new Student(name, examid, idcard, location, score);

             boolean bool=asi.addStudent(stu);
             if(bool){
                 System.out.println("学生添加成功");
             }else{
                 System.out.println("添加失败");
             }

             continue;
         case 2:
             System.out.println("请输入要删除的学生姓名");
             String removeName=input.next();
             Student stu2=new Student();
             //stu2.setName(removeName);

             RemoveStuImpl re=new RemoveStuImpl();
             //boolean bool2=re.removeStu(stu2);
             boolean bool2=asi.removeStudent(removeName);
             if(bool2){
                 System.out.println("删除成功");
             }else{
                 System.out.println("删除失败");
             }
             continue;
         case 3:
             System.out.println("请输入学生考号");
             String examid1=input.next();
             Student stu3=asi.caxunStudent(examid1);
             if(stu3!=null){
                 System.out.println("学生的身份证是"+stu3.getIdcard()+",准考证"+stu3.getExamid()+
                         ",姓名"+stu3.getName()+",分数是: "+stu3.getScore()+",地址"+stu3.getLocation());
             }else{
                 System.out.println("查无此人");
             }
             continue;
         case 4:
             System.out.println("系统退出");
             break;
         }
         break;
     }while(true);

    }
 }

本文没有使用工具类,后续可自行添加!!!!!