java学习笔记（xml解析）

java学习笔记（xml解析）

最近学习xml，把学习的代码发上来   希望对新手有用
这是note.xml

<? xml version = " 1.0 "  encoding = " gb2312 "   ?>  
< notes >
< note date = " 2007-4-12 " >
< from > 小红 </ from >  
< to > 小林 </ to >  
< message > 周末一起去吃火锅呀 </ message >  
</ note >
</ notes >

这是dom解析xml代码

import  java.io.File;
import  java.io.FileInputStream;
import  java.io.FileNotFoundException;
import  java.io.IOException;
import  java.io.InputStream;

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

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


class   DomXMLTest
{
     public   static   void  main(String[] args)
    {   
         try {
          // （1）得到DOM解析器的工厂实例
        DocumentBuilderFactory factory  = DocumentBuilderFactory.newInstance();     
           // （2）从DOM工厂获得DOM解析器
        DocumentBuilder  builder = factory.newDocumentBuilder(); 
        File f = new  File( " note.xml " );
          // （3）把要解析的XML文档转化为输入流，以便DOM解析器解析它
        InputStream  is = new  FileInputStream(f);  
         // （4）解析XML文档的输入流，得到一个Document
        Document doc = builder.parse(is);    
         // （5）得到XML文档的根节点
        Element  root = doc.getDocumentElement(); 
          // （6）得到节点的子节点
        NodeList  notes = root.getChildNodes();   

           for ( int  i = 0 ;i < notes.getLength();i ++ )
          {
               Node note = notes.item(i);
             if (note.getNodeType() == Node.ELEMENT_NODE)
                {  
                     // （7）取得节点的属性值
                    String date  = note.getAttributes().getNamedItem( " date " ).getNodeValue(); 
                    System.out.println(date);
                     //  （8）轮循子节点
                     for (Node node = note.getFirstChild();node != null ;node = node.getNextSibling()) 
                         {
                                 if (node.getNodeType() == Node.ELEMENT_NODE)
                                     {
                                             if (node.getNodeName().equals( " from " ))
                                            {
                                                 String from = node.getFirstChild().getNodeValue();
                                                 System.out.println(from);
                                             }
                                             if (node.getNodeName().equals( " to " ))
                                             {
                                                  String to = node.getFirstChild().getNodeValue();
                                                   System.out.println(to);
                                             }
                                              if (node.getNodeName().equals( " message " ))
                                             {
                                                   String message = node.getFirstChild().getNodeValue();
                                                   System.out.println(message);
                                              }
                                      }
                           }
                  }

        }
        }
         catch (ParserConfigurationException e)
        {
            e.printStackTrace();
        }
         catch (SAXException e)
        {
            e.printStackTrace();
        }
         catch (IOException e)
        {
            e.printStackTrace();
        }
     }                                  
}

还有 出现 下面的错误  是xml的格式不对 ，我就应为在 <?xml 前面多个空格 就找了好几天的错误
特别感谢那些帮我找问题的高手，用范伟的话说  谢谢啊

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