java怎么读写xml文件

谁说不自带的rt.jar就是啊

1.接口

/**
 * 
 */
package com.huawei.liyong.interfaces;

import java.util.Map;

/**
 * @author Administrator
 */
public interface OperateTool
{

 /**
  * 解析XML
  */
 Map parseXML( String xmlPath, String root );

 /**
  * 写入文件
  */
 void writeToFile( String filePath, String content );

 /**
  * 排序
  */
 void orderScore( Map map, String resultPath );

}

2.实体Bean 学生

/*
 * 文件名：   Student.java
 * 版权：    〈版权〉
 * 描述：    〈描述〉
 * 撰写人：   Administrator
 * 修改时间： Jul 31, 2011
 * 跟踪单号：〈跟踪单号〉
 * 修改单号：〈修改单号〉
 * 修改内容：〈修改内容〉
 */

package com.huawei.liyong.bean;

/**
 *

 * Description: //描述类的信息和作用
 * 
 * @author Administrator
 */
public class Student
{
 private String name;

 private String place;

 private String score;

 /**
  * @return the name
  */
 public String getName()
 {
  return name;
 }
 /**
  * @param name
  *            the name to set
  */
 public void setName( String name )
 {
  this.name = name;
 }
 /**
  * @return the place
  */
 public String getPlace()
 {
  return place;
 }
 /**
  * @param place
  *            the place to set
  */
 public void setPlace( String place )
 {
  this.place = place;
 }
 /**
  * @return the score
  */
 public String getScore()
 {
  return score;
 }
 /**
  * @param score
  *            the score to set
  */
 public void setScore( String score )
 {
  this.score = score;
 }
 
 /*
  * (non-Javadoc)
  * 
  * @see java.lang.Object#toString()
  */
 @Override
 public String toString()
 {
  return new StringBuffer().append(
   Student.class.getName() 
   + "[name=" 
   + this.name 
   + ",place="
   + this.place 
   + ",score=" 
   + this.score
   + "]").toString();
 }

}

3.具体操作类

/**
 * 
 */
package com.huawei.liyong.action;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

import com.huawei.liyong.bean.Student;
import com.huawei.liyong.interfaces.OperateTool;

/**
 * @author Administrator
 */
public class OperaterAction
{

 /**
  * @param args
  */
 public static void main( String[] args )
 {
  Operator o = new Operator();
  o.orderScore(o.parseXML("student.xml", "student"), "result.txt");
 }
}

class Operator implements OperateTool
{

 private DocumentBuilderFactory dbf;

 private DocumentBuilder db;

 private Document document;

 private NodeList nodeList;

 private Map map = new HashMap();

 private Student student = new Student();

 public Map parseXML( String xmlPath, String root )
 {
  // TODO parseXML
  try
  {
   dbf = DocumentBuilderFactory.newInstance();
   db = dbf.newDocumentBuilder();
   document = db.parse(xmlPath);
   nodeList = document.getElementsByTagName(root);
   for( int j = 0; j < nodeList.getLength(); j++ )
   {
    map.put("all" + j, nodeList.item(j).getChildNodes().item(1)
     .getTextContent()
      + ","
      + nodeList.item(j).getChildNodes().item(3)
       .getTextContent()
      + ","
      + nodeList.item(j).getChildNodes().item(5)
       .getTextContent());
   }
  }
  catch(ParserConfigurationException e)
  {
   e.printStackTrace();
  }
  catch(SAXException e)
  {
   e.printStackTrace();
  }
  catch(IOException e)
  {
   e.printStackTrace();
  }
  return map;
 }

 public void writeToFile( String filePath, String content )
 {
  FileWriter fw = null;
  File f = null;
  try
  {
   f = new File(filePath);
   fw = new FileWriter(f);
   fw.write(content);
   fw.flush();
  }
  catch(IOException e)
  {
   e.printStackTrace();
  }
  finally
  {
   try
   {
    if(null != fw)
    {
     fw.close();
    }
   }
   catch(IOException e)
   {
    e.printStackTrace();
   }
  }
 }
 public void orderScore( Map maps, String resultPath )
 {
  String[] array = null;
  StringBuffer buffer = new StringBuffer();
  StringBuffer sbf = new StringBuffer();
  String temp = "";
  for( int i = 0; i < maps.size(); i++ )
  {
   buffer.append(maps.get("all" + i) + ";");
  }
  array = buffer.toString().split(";");
  for( int i = 0; i < array.length; i++ )
  {
   for( int j = i; j < array.length; j++ )
   {
    if(Integer.parseInt(array[i].substring(array[i]
     .lastIndexOf(",") + 1, array[i].length())) < Integer
     .parseInt(array[j].substring(array[j].lastIndexOf(",") + 1,
      array[j].length())))
    {
     temp = array[j];
     array[j] = array[i];
     array[i] = temp;
    }
   }
  }
  for( int i = 0; i < array.length; i++ )
  {
   student.setName(array[i].split(",")[0]);
   student.setPlace(array[i].split(",")[1]);
   student.setScore(array[i].split(",")[2]);
   sbf.append(student.toString() + "\n");
   writeToFile(resultPath, sbf.toString());
  }
 }
}

呵呵，给你一个
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.List;

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;
import org.jdom.xpath.XPath;

/**
* xml 工具类 先调用init(),后边使用xpath获取element内容
*
* @author changlei
*
*/
public class CommonXMLUtil {

protected SAXBuilder builder;
protected Document document;

public CommonXMLUtil() {
super();
}

/**
* 初始化
*
* @param xmlStr
* @throws JDOMException
* @throws IOException
*/
public void init(String xmlStr) throws JDOMException, IOException {
builder = new SAXBuilder();
ByteArrayInputStream ins = null;
ins = new ByteArrayInputStream(xmlStr.getBytes("utf-8"));
document = builder.build(ins);
}

/**
* 初始化
*
* @param xmlStr
* @throws JDOMException
* @throws IOException
*/
public void init(String xmlStr,String encode) throws JDOMException, IOException {
builder = new SAXBuilder();
ByteArrayInputStream ins = null;
ins = new ByteArrayInputStream(xmlStr.getBytes(encode));
document = builder.build(ins);
}

/**
* 获取element的值
*
* @param xpath
* @return
* @throws JDOMException
*/
public String getElementValue(String xpath) throws JDOMException {
String val = null;
Element element = (Element) XPath.selectSingleNode(
document.getRootElement(), xpath);
if (element != null) {
val = element.getValue();
}
return val;
}

/**
* 获取element attribute的值
*
* @param xpath
* @return
* @throws JDOMException
*/
public String getAttrValue(String elementXpath,String attrName) throws JDOMException {
String val = null;
Element element = (Element) XPath.selectSingleNode(
document.getRootElement(), elementXpath);
if (element != null) {
val = element.getAttributeValue(attrName);
}
return val;
}

}

调用范例
CommonXMLUtil xmlUtil = new CommonXMLUtil();
xmlUtil.init(messageBody, "GBK");
// 根据响应码解析交易结果
String retCode = xmlUtil
.getElementValue("/BOSEBankData/opRep/retCode");
String retMsg = xmlUtil
.getElementValue("/BOSEBankData/opRep/errMsg");
String orgOrderNo = xmlUtil
.getElementValue("/BOSEBankData/opRep/serialNo");

public List doReadXML(String path) throws Exception {
List empvoList = new ArrayList();

File file = new File(path);
//输入流对象
FileInputStream fis = new FileInputStream(file);
//jdom解析器
SAXBuilder sb = new SAXBuilder();
Document doc= sb.build(fis);
//获得XML的根元素
Element root = doc.getRootElement();
//获得根元素下的所有子元素
List employees = root.getChildren();
for(int i=0;i Element employee =employees.get(i);
Student stu= new Student();
String name = employee.getChildText("name");
String sex = employee.getChildText("sex");
String agetemp = employee.getChildText("age");
String home = employee.getChildText("home");
String email = employee.getChildText("email");

stu.setName(name);
stu.setSex(sex);
int age = 0;
if(agetemp.equals("")){
age = 0;
} else {
age = Integer.parseInt(agetemp);
}
stu.setAge(age);
stu.setHome(home);
stu.setEmail(email);
System.out.println(name+"\t"+i);
empvoList.add(stu);
}
return empvoList;
}

用dom4j的XMLWriter类可以写入数据

先创建节点，形成一个document对象，然后通过dom4j里的什么类write出去（具体代码我也不知道了），很久不用了。