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Simple API for XML
SAX是一套API,不是一个解析器,所以这个代码在XML解析器中是通用的。要让示例跑起来,需要一个支持SAX v2的XML解析器。实现了SAX的解析器有很多,比如Apache的Xerces,Oracle的XML Parser等等。
解析时需实现ContentHandler或者扩展DefaultHandler类,将XML解析器解析一个特定的文档即可。


示例:
xml文件
<?xml version="1.0"?>
<simple date="7/7/2000" >
   <name> Bob </name>
   <location> New York </location>
</simple>

接下来,我们看看第一个XML解析例子的代码:


import org.xml.sax.*;
import org.xml.sax.helpers.*;
import java.io.*;


public class Example1 extends DefaultHandler {


   // 重载DefaultHandler类的方法
   // 以拦截SAX事件通知。
   //
        // 关于所有有效事件,见org.xml.sax.ContentHandler
   //
   public void startDocument( ) throws SAXException {
      System.out.println( "SAX Event: START DOCUMENT" );
   }

   public void endDocument( ) throws SAXException {
      System.out.println( "SAX Event: END DOCUMENT" );
   }

   public void startElement( String namespaceURI,
              String localName,
              String qName,
              Attributes attr ) throws SAXException {
         System.out.println( "SAX Event: START ELEMENT[ " +
                  localName + " ]" );

      // 如果有属性,我们也一并打印出来...
                for ( int i = 0; i < attr.getLength(); i++ ){
                   System.out.println( "   ATTRIBUTE: " +
                  attr.getLocalName(i) +
                  " VALUE: " +
                  attr.getValue(i) );
      }

   }

   public void endElement( String namespaceURI,
              String localName,
              String qName ) throws SAXException {
      System.out.println( "SAX Event: END ELEMENT[ " +
                  localName + " ]" );
   }

   public void characters( char[] ch, int start, int length )
                  throws SAXException {

      System.out.print( "SAX Event: CHARACTERS[ " ];

      try {
         OutputStreamWriter outw = new OutputStreamWriter(System.out);
         outw.write( ch, start,length );
         outw.flush();
      } catch (Exception e) {
         e.printStackTrace();
      }

      System.out.println( " )" );

   }


   public static void main( String[] argv ){

      System.out.println( "Example1 SAX Events:" );
      try {

         // 建立SAX 2解析器...
         XMLReader xr = XMLReaderFactory.createXMLReader();

         // 安装ContentHandler...
         xr.setContentHandler( new Example1() );

            // 解析文件...
         xr.parse( new InputSource(
               new FileReader( "Example1.xml" )) );


      }catch ( Exception e )  {
         e.printStackTrace();
      }

   }

}

最后,就得到了运行第一个例子解析我们的XML样本文档所产生的输出:


Example1 SAX Events:
SAX Event: START DOCUMENT
SAX Event: START ELEMENT[ simple ]
   ATTRIBUTE: date VALUE: 7/7/2000
SAX Event: CHARACTERS[
    ]
SAX Event: START ELEMENT[ name ]
SAX Event: CHARACTERS[  Bob  ]
SAX Event: END ELEMENT[ name ]
SAX Event: CHARACTERS[
    ]
SAX Event: START ELEMENT[ location ]
SAX Event: CHARACTERS[  New York  ]
SAX Event: END ELEMENT[ location ]
SAX Event: CHARACTERS[
]
SAX Event: END ELEMENT[ simple ]
SAX Event: END DOCUMENT

如你所见,SAX解析器会为每个在XML文档中出现的SAX事件调用正确的ContentHandler成员方法。

posted on 2007-05-31 16:20 李大嘴 阅读(413) 评论(0)  编辑  收藏

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