Simple API for XML
SAX是一套API,不是一個解析器,所以這個代碼在XML解析器中是通用的。要讓示例跑起來,需要一個支持SAX v2的XML解析器。實現了SAX的解析器有很多,比如Apache的Xerces,Oracle的XML Parser等等。
解析時需實現ContentHandler或者擴展DefaultHandler類,將XML解析器解析一個特定的文檔即可。示例:
xml文件
<?xml version="1.0"?>
<simple date="7/7/2000" >
<name> Bob </name>
<location> New York </location>
</simple>
接下來,我們看看第一個XML解析例子的代碼:
import org.xml.sax.*;
import org.xml.sax.helpers.*;
import java.io.*;
public class Example1 extends DefaultHandler {
// 重載DefaultHandler類的方法
// 以攔截SAX事件通知。
//
// 關于所有有效事件,見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 + " ]" );
// 如果有屬性,我們也一并打印出來...
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();
// 安裝ContentHandler...
xr.setContentHandler( new Example1() );
// 解析文件...
xr.parse( new InputSource(
new FileReader( "Example1.xml" )) );
}catch ( Exception e ) {
e.printStackTrace();
}
}
}
最后,就得到了運行第一個例子解析我們的XML樣本文檔所產生的輸出:
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
如你所見,SAX解析器會為每個在XML文檔中出現的SAX事件調用正確的ContentHandler成員方法。
posted on 2007-05-31 16:20
李大嘴 閱讀(421)
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