XML为数据库进行增删改查（实例）

//增删改查文件

package xml2;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;
import org.xml.sax.XMLReader;

public class Dom4jReadExmple {
 public File file =new File(System.getProperty("user.dir")+File.separator+"dd"+File.separator+"hy.xml");
 //遍历所有
 public void getSelectedNodeValue(List<Student> list){
  if(!file.exists()){
   System.out.println("文件不存在");
  }
  SAXReader saxReader = new SAXReader();
  try {
   Document document= saxReader.read(file);
   Element rootElement= document.getRootElement();
   Iterator iterator=document.selectNodes("//student").iterator();
   while(iterator.hasNext()){
    Student student = new Student();
    College college = new College();
    Element elem =(Element) iterator.next();
    student.setAge(Integer.parseInt(elem.attributeValue("age")==null?"0":elem.attributeValue("age")));
    student.setName(elem.element("name").getText());
    college.setName(elem.element("college").getText());
    college.setLeader(elem.element("college").attributeValue("leader"));
    student.setCollege(college);
    student.setTelephone(elem.elementText("telephone"));
    student.setNote(elem.elementText("notes"));
    
    System.out.println(student.getName());
    System.out.println(student.getAge());
    System.out.println(student.getTelephone());
    System.out.println(student.getCollege().getName());
    System.out.println(student.getCollege().getLeader());
    System.out.println(student.getNote());
    System.out.println("============================");
    list.add(student);
   }
   
  } catch (DocumentException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
 }
 //插入数据
 public void insertIntoXML(Student stu){
  try {
   if(!file.exists()){
    file.createNewFile();
    PrintWriter writer =new PrintWriter(new FileOutputStream(file));
    writer.write("<?xml version='1.0' encoding='UTF-8'?>");
    writer.write("\n");
    writer.write("<all>");
    writer.write("\n");
    writer.write("</all>");
    writer.flush();
    writer.close();
//    或
//    BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file)));
//    bufferedWriter.write("<?xml version='1.0' encoding='UTF-8'?>");
//    bufferedWriter.write("\n");
//    bufferedWriter.write("<all>");
//    bufferedWriter.write("\n");
//    bufferedWriter.write("</all>");
//    bufferedWriter.flush();
//    bufferedWriter.close();
   }
  Document document= DocumentHelper.createDocument();
  Element root=document.addElement("students");
  root.addComment("所有部门信息");
  Element element =root.addElement("student");
  element.addAttribute("id", stu.getId().toString());
  element.addElement("age").addText(stu.getAge().toString());
  element.addElement("name").addText(stu.getName());
  Element element2 =element.addElement("college");
  element2.addText(stu.getCollege().getName());
  element2.addAttribute("leader", stu.getCollege().getLeader());
  element.addElement("telephone").addText(stu.getTelephone());
  element.addElement("notes").addText(stu.getNote());
  
  SAXReader saxReader = new SAXReader();
  Document document2=saxReader.read(file);
   if(null!=document2){
    List lists=document2.selectNodes("//student");
    if(null!=lists&&lists.size()>0){
     Iterator iterator =lists.iterator();
     while(iterator.hasNext()){
      Element element4 =(Element) iterator.next();
      Element element5 =root.addElement("student");
      element5.addAttribute("id", element4.attributeValue("id"));
      element5.addElement("age").addText(element4.elementText("age"));
      element5.addElement("name").addText(element4.elementText("name"));
      element5.addElement("college").addText(element4.elementText("college")).addAttribute("leader", element4.element("college").attributeValue("leader"));
      element5.addElement("telephone").addText(element4.elementText("telephone"));
      element5.addElement("notes").addText(element4.elementText("notes"));
     }
    }
   }
   XMLWriter xmlWriter = new XMLWriter(new FileOutputStream(file));
   xmlWriter.write(document);
   xmlWriter.close();
  } catch (DocumentException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (UnsupportedEncodingException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (FileNotFoundException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  
  
 }
// 通过id删除
 public void deleteFormXml(int id){
  SAXReader saxReader = new SAXReader();
  try {
   Document document=saxReader.read(file);
   Iterator iterator=document.selectNodes("//student[@id]").iterator();
   while(iterator.hasNext()){
    Element element =(Element) iterator.next();
    if(element.attributeValue("id").equals(String.valueOf(id))){
     document.getRootElement().remove(element);
    }
   }
   XMLWriter xmlWriter = new XMLWriter(new FileOutputStream(file));
   xmlWriter.write(document);
   xmlWriter.flush();
   xmlWriter.close();
   
  } catch (DocumentException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (UnsupportedEncodingException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (FileNotFoundException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
 }
// 修改对应id数据
 public void editXML(Student stu){
  SAXReader saxReader =new SAXReader();
  try {
   Document document =saxReader.read(file);
   Iterator iterator=document.selectNodes("//student[@id]").iterator();
   while(iterator.hasNext()){
    Element element =(Element) iterator.next();
    if(element.attributeValue("id").equals(String.valueOf(stu.getId()))){
     element.element("name").setText(stu.getName());
     element.element("age").setText(stu.getAge().toString());
     element.element("college").setText(stu.getCollege().getName());
     element.element("college").setAttributeValue("leader", stu.getCollege().getLeader());
     element.element("telephone").setText(stu.getTelephone());
     element.element("notes").setText(stu.getNote());
    }
   }
   XMLWriter xmlWriter = new XMLWriter(new FileOutputStream(file));
   xmlWriter.write(document);
   xmlWriter.flush();
   xmlWriter.close();
  } catch (DocumentException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (UnsupportedEncodingException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (FileNotFoundException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
 }
 
}