JAVA对XML的添、删、改、查操作

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import org.w3c.dom.*;
import org.xml.sax.SAXException;

import javax.xml.parsers.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.*;
import javax.xml.xpath.*;

public class testXmlRoles {
 
 public static void main(String[] args) {
  if(args.length>0){   
   String method = args[0];
   DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
   //根节点
   Element root = null;
   //子节点
   Element theRole = null;
   //子节点元素
   Element theElem = null;
   try {
    factory.setIgnoringElementContentWhitespace(true);
    DocumentBuilder db = factory.newDocumentBuilder();
    Document xmldoc = db.parse(new File("Test.xml"));
    root = xmldoc.getDocumentElement();
             //--- 新建一角色(子节点) ----
       //调用格式 :java TestXmlRoles add newrole 12 123456
    if(method.equals("add")){
      if(args.length!=4){
       System.out.println("请输入四个参数:格式例如-->java TestXmlRoles add newrole 12 123456"); 
      }else{
       theRole = (Element) selectSingleNode("/roles/role[name='" + args[1] + "' and id='"+args[2]+"']", root);
       if(theRole!=null){
        System.out.println("---该name或者id已经存在,请另设----");
       }else{
        theRole = xmldoc.createElement("role"); 
        //附加子节点元素   
        theElem = xmldoc.createElement("name");
        theElem.setTextContent(args[1]);   
        theRole.appendChild(theElem);
        
        theElem = xmldoc.createElement("id");
        theElem.setTextContent(args[2]);
        theRole.appendChild(theElem);
        
        theElem = xmldoc.createElement("pas");
        theElem.setTextContent(args[3]);
        theRole.appendChild(theElem);
        //根节点附加子节点
        root.appendChild(theRole);   
        output(xmldoc);
        saveXml("Test.xml", xmldoc);
        System.out.println("---添加成功----");
       }       
      }      
     }
     
   //--- 要用id属性删除角色 ----
   //调用格式 :java TestXmlRoles delbyid 12
     else if (method.equals("delbyid")) {
     if (args.length != 2) {
      System.out.println("请输入id:格式例如-->java TestXmlRoles delbyid 12");
     } else {
      theRole = (Element) selectSingleNode("/roles/role[id='"+ args[1] + "']", root);
      if (theRole != null) {
       theRole.getParentNode().removeChild(theRole);
       saveXml("Test.xml", xmldoc);
       System.out.println("---删除成功----");
      } else {
       System.out.println("--不存在该id的角色 ----");
      }

     }
    }
     
           //--- 要用name属性删除角色 ----
     //调用格式 :java TestXmlRoles delbyname newrole
      else if (method.equals("delbyname")) {
     if (args.length != 2) {
      System.out.println("请输入name参数:格式例如-->java TestXmlRoles delbyname newrole");
     } else {
      theRole = (Element) selectSingleNode("/roles/role[name='" + args[1] + "']", root);
      if (theRole != null) {
       theRole.getParentNode().removeChild(theRole);
       saveXml("Test.xml", xmldoc);
       System.out.println("---删除成功----");
      } else {
       System.out.println("---不存在名称对应的角色----");
      }
     }
    }
     
     //根据name查找id,pas
     //调用格式 java TestXmlRoles findbyname newrole
     else if (method.equals("findbyname")) {
     if (args.length != 2) {
      System.out.println("请输入name参数:格式例如-->java TestXmlRoles findbyname newrole");
     } else {
      theRole = (Element) selectSingleNode("/roles/role[name='" + args[1] + "']", root);
      if (theRole != null) {
       // getElementsByTagName返回的是NodeList，所以要跟上item(0)
       String password = theRole.getElementsByTagName("pas").item(0).getTextContent();
       String id = theRole.getElementsByTagName("id").item(0).getTextContent();
       System.out.println("---  对应角色id 和密码:----" + id+ "," + password);
      } else {
       System.out.println("---不存在该名称的角色---");
      }
     }
    }
     
                 // 根据id查找name,pas
    // 调用格式 java TestXmlRoles findbyid 30
    else if (method.equals("findbyid")) {
     if (args.length != 2) {
      System.out.println("请输入id参数:格式例如-->java TestXmlRoles findbyid 30");
     } else {
      theRole = (Element) selectSingleNode("/roles/role[id='"+ args[1] + "']", root);
      if(theRole!=null){
                            //getElementsByTagName返回的是NodeList，所以要跟上item(0)
       String password = theRole.getElementsByTagName("pas").item(0).getTextContent();
       String name = theRole.getElementsByTagName("name").item(0).getTextContent();
       System.out.println("---  对应角色id 和密码:----" + name + ","+ password);
      }else{
       System.out.println("---没有找到相关记录---");
      }      
     }
    }
     
     // --- 根据name对role做一些修改。 ----
     //调用格式 java TestXmlRoles editbyname cs 8888888
    else if(method.equals("editbyname")){
       if(args.length!=2){
      System.out.println("请输入name参数:格式例如-->java TestXmlRoles editbyname cs 8888888"); 
       }else{
      theRole = (Element) selectSingleNode("/roles/role[name='"+args[1]+"']",root);
                        if(theRole!=null){
                            //--- 修改角色密码 -----
                         //getElementsByTagName返回的是NodeList，所以要跟上item(0)
          theRole.getElementsByTagName("pas").item(0).setTextContent(args[2]);
          /*// --- 给节点加一个属性'id'，值为B01 ----
          theRole.setAttribute("id", "B01");
          output(theRole);*/
          saveXml("Test.xml", xmldoc);
      }else{
       System.out.println("---没有找到相关记录---");
      }      
      }
        }
     
     //批量删除
     //调用格式 java TestXmlRoles delbanch id<10
    else if(method.equals("delbanch")){
      if(args.length!=2){
      System.out.println("请输入删除条件:格式例如-->java TestXmlRoles delbanch id<10"); 
      }else{
                     //NodeList someRoles = selectNodes("/roles/role[id<10]", root);
      NodeList someRoles = selectNodes("/roles/role["+args[2]+"]", root);
      System.out.println("---  符合条件的角色有　" + someRoles.getLength()+ "个 ---");
      for (int i = 0; i < someRoles.getLength(); i++) {
       someRoles.item(i).getParentNode().removeChild(someRoles.item(i));
      }
      saveXml("Test.xml", xmldoc);
      }
      }else{
                 System.out.println("--- 请输入正确的方法名称---");
      }
   } catch (ParserConfigurationException e) {
    e.printStackTrace();
   } catch (SAXException e) {
    e.printStackTrace();
   } catch (IOException e) {
    e.printStackTrace();
   }
  } else {
   System.out.println("调用该程序需要输入相关参数:格式例如-->java TestXmlRoles add newrole 12 123456");
  }  
 }

//  将node的XML字符串输出到控制台
 public static void output(Node node) {
  TransformerFactory transFactory = TransformerFactory.newInstance();
  try {
   Transformer transformer = transFactory.newTransformer();
   transformer.setOutputProperty("encoding", "gb2312");
   transformer.setOutputProperty("indent", "yes");

   DOMSource source = new DOMSource();
   source.setNode(node);
   StreamResult result = new StreamResult();
   result.setOutputStream(System.out);

   transformer.transform(source, result);
  } catch (TransformerConfigurationException e) {
   e.printStackTrace();
  } catch (TransformerException e) {
   e.printStackTrace();
  }
 }

//  查找节点，并返回第一个符合条件节点
 public static Node selectSingleNode(String express, Object source) {
  Node result = null;
  XPathFactory xpathFactory = XPathFactory.newInstance();
  XPath xpath = xpathFactory.newXPath();
  try {
   result = (Node) xpath.evaluate(express, source, XPathConstants.NODE);
  } catch (XPathExpressionException e) {
   e.printStackTrace();
  }

  return result;
 }

//  查找节点，返回符合条件的节点集。
 public static NodeList selectNodes(String express, Object source) {
  NodeList result = null;
  XPathFactory xpathFactory = XPathFactory.newInstance();
  XPath xpath = xpathFactory.newXPath();
  try {
   result = (NodeList) xpath.evaluate(express, source,XPathConstants.NODESET);
  } catch (XPathExpressionException e) {
   e.printStackTrace();
  }

  return result;
 }

//  将Document输出到文件
 public static void saveXml(String fileName, Document doc) {
  TransformerFactory transFactory = TransformerFactory.newInstance();
  try {
   Transformer transformer = transFactory.newTransformer();
   transformer.setOutputProperty("indent", "yes");

   DOMSource source = new DOMSource();
   source.setNode(doc);
   StreamResult result = new StreamResult();
   result.setOutputStream(new FileOutputStream(fileName));

   transformer.transform(source, result);
  } catch (TransformerConfigurationException e) {
   e.printStackTrace();
  } catch (TransformerException e) {
   e.printStackTrace();
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  }
 }
}

XML文件：

 
  a
  10
  789456
 
 
  b
  20
  654321
 
  
   

cs
30
8888888