一个最最简单的xml sax writer.

    JAVA 的xml包不少，可就没找到一个包提供了SAX writer的功能，正好需要按照SAX方式输出xml文件，所以自己写了一个，包含注释大约100行，使用起来也颇为简单。
    /*
     * Created on 2005-1-29
     *
     *  Mininal sax writer. you can use it like that:
     *   XmlWriter.startDocument();
     *   ...
     *   XmlWriter.startElement("Book");                        
     *   XmlWriter.addAttribute("title","book title");       
     *   XmlWriter.addAttribute("price","$100");       
     *   XmlWriter.character("This is a good book");                        
     *   XmlWriter.endElement("Book");
     *   ...
     *   XmlWriter.endDocument();
     */
    package com.dyz.xfe;

    import java.io.*;

    public class XmlWriter{
 
     private BufferedWriter writer = null;
     private StringBuffer buffer = new StringBuffer();
     private boolean isRoot = true;
     private boolean closed = false;
 
     public XmlWriter(String filename)
     {
      try {
           writer = new BufferedWriter( new FileWriter(filename) );
      } catch (IOException e) {   
           e.printStackTrace();
      } 
     }
 
     public void startDocument()
     {  
      try {
           writer.write("");
      } catch (IOException e) {
           e.printStackTrace();
      }  
     }
 
     public void endDocument()
     {
      try {
       if( buffer.length() > 0 )
            writer.write(buffer.toString());
           writer.close();
      } catch (IOException e) {
           e.printStackTrace();
      }
     }
 
     public void startElement(String elem)
     {
      if( isRoot )
           isRoot = false;
      else
      {
           if( !closed )
           buffer.append(">");
      }
      if( buffer.length() > 4096 )
      {
           try {
                writer.write(buffer.toString());
           } catch (IOException e) {
        e.printStackTrace();
       }
       buffer.delete(0,buffer.length());
      }  
      buffer.append("<" + elem); 
      closed = false;
     }
 
     public void endElement(String elem)
     {
          if( !closed )
               buffer.append(">");
          buffer.append("");
          closed = true;
     }
 
     /**
      * Output a xml attribute.
      * @param name attribute name.
      * @param value attribute value.
      */
     public void addAttribute(String name, String value)
     {  
          buffer.append( " " + name + "=/"" + value + "/"" );
     }
 
     /**
      * Output a text node.
      * @param value
      */
     public void character(String value)
     {
          if( !closed )
               buffer.append(">");
          buffer.append(value);
          closed = true;
     }
    }

    其实还可以做进一步优化，不过对于一些简单的需求完全足够，只是不明白JAXP就不提供？