使用SAX过滤器将新元素插入XML文件 [英] Insert new element to an XML file using SAX Filter

问题描述

 <？xml version =1.0encoding =UTF- 8\" >？; 
<游戏> 
<移动> 
< turn> 2< / turn> 
< piece nr =1/> 
< turn> 4< / turn> 
< piece nr =1/> 
 
< /移动> 
< /游戏> 
  

我正在编写一个Java程序，将XML文件作为输入，然后使用SAX和SAX过滤器并计算：

• 转动元素的内容之和（这里= 6）
  
• 然后我想要使用一个SAX过滤器来生成一个输出XML文件，这个文件就是这个文件的一部分（这里是= 2）
  
  
  

  与输入相同，但有一个额外的元素：
  
  

   < s：statistics> 
  < s：turn-total> 6< / s：turn-total> 
  < s：件数> 2< / s：件数> 
  < / s：统计信息> 
    

  前缀 s 是对。

  
  
  

  我的程序如此很远是：
  
  pre $ public class test {
public static void main（String [] args）throws Exception {
if（args.length！= 2）{
System.err.println（error）;
System.exit（1）;
}
String xmlInput = args [0];
String filteredXML = args [1];
test test1 = new test（）;
test1.sax（xmlInput，filteredXML）;
}
private void sax（String gameXML，String filteredGameXML）throws Exception {
FileInputStream fis = new FileInputStream（gameXML）;
InputSource is = new InputSource（fis）;
XMLReader xr = XMLReaderFactory.createXMLReader（）;
XMLFilter xf = new MyFilter（）;
xf.setParent（xr）;
xr = xf;
xr.parse（is）;
xr.setFeature（http://xml.org/sax/features/namespaces，true）;
DefaultHandler handler = new DefaultHandler（）;
xr.setContentHandler（handler）;
}
private class MyFilter extends XMLFilterImpl {
StringBuffer buffer;
int temp = 0;
int sum = 0;
String ff;
int numof = 0;
private MyFilter（）{}
$ b @Override
public void startDocument（）throws SAXException {
System.out.println（START DOCUMENT）;
numof = 0;

$ b $ public void startElement（String namespaceURI，String localName，String name，Attributes attributes）throws SAXException {
if（localName.equals（turn））{
buffer = new StringBuffer（）;

if（piece.equals（name））{
numof ++;


$ b $ public void characters（char [] ch，int start，int length）throws SAXException {
String s = new String（ch，start，长度）;
if（buffer！= null）{
buffer.append（s）;


$ b $ public void endElement（String uri，String localName，String name）throws SAXException {
if（buffer！= null）{
FF = buffer.toString（）;
temp = Integer.valueOf（ff）;
sum = sum + temp;
}
buffer = null;
}
public void endDocument（）throws SAXException {
System.out.println（END DOCUMENT）;
System.out.println（sum of turn：+ sum）;
System.out.println（sum of piece：+ numof）;



$ b $ / code>

  我做下一步？

  解决方案您的 XMLFilter 应委托给另一个 ContentHandler ，它基于sax事件序列化文档。
  
  

    SAXTransformerFactory factory = SAXTransformerFactory）TransformerFactory.newInstance（）; 
   TransformerHandler serializer = factory.newTransformerHandler（）; 
  结果结果=新的StreamResult（...）; 
   serializer.setResult（result）; 
   
   XMLFilterImpl filter = new MyFilter（）; 
   filter.setContentHandler（serializer）; 
   
   XMLReader xmlreader = XMLReaderFactory.createXMLReader（）; 
   xmlreader.setFeature（http://xml.org/sax/features/namespaces，true）; 
   xmlreader.setFeature（http://xml.org/sax/features/namespace-prefixes，true）; 
   xmlreader.setContentHandler（filter）; 
   
   xmlreader.parse（new InputSource（...））; 
    

  您的回调应委派给 super 执行，将事件转发到序列化 ContentHandler 。

    public void startElement （String namespaceURI，String localName，String qName，Attributes atts）throws SAXException {
   super.startElement（namespaceURI，localName，qName，atts）; 
   
   
   
   
   $ p $  endElement 
   
   
   
   
    public void endElement（String namespaceURI，String localName，String qName）throws SAXException {
   super.endElement（namespaceURI，localName，qName）; 
   if（game.equals（localName））{
   super.startElement（，statistics，statistics，new AttributesImpl（））; 
   char [] chars = String.valueOf（num）.toCharArray（）; 
   super.characters（chars，0，chars.length）; 
   super.endElement（，statistics，statistics）; 
  } 
   ... 
  } 
    
   
  I have an XMl file that looks like:
  <?xml version="1.0" encoding="UTF-8"?>
  <game >
    <moves>
      <turn>2</turn>
      <piece nr="1" />
      <turn>4</turn>
      <piece nr="1" />
  
    </moves>
  </game>
  I am writing a Java program that takes the XML file as input then parses it with SAX and SAX filter and computes:
  
  
  the sum of the content of turn element (here=6)
  the number of piece elements (here=2) 
  
  
  Then I want to use a SAX filter in order to generate an output XML file that are the same as the input one but with an additional element like:
  <s:statistics>
      <s:turn-total>6</s:turn-total>
      <s:piece-count>2</s:piece-count>
  </s:statistics>
  The prefix s is a reference to a namespace.
  
  My program so far is:
   public class test{     
           public static void main(String[] args) throws Exception {
                  if (args.length != 2) {
                  System.err.println("error ");
                  System.exit(1);
                  }
                  String xmlInput = args[0];
                  String filteredXML = args[1];
                  test test1 = new test();
                      test1.sax(xmlInput, filteredXML);
              }
      private void sax(String gameXML, String filteredGameXML)throws Exception{
          FileInputStream fis = new FileInputStream( gameXML);
          InputSource is = new InputSource(fis);
          XMLReader xr = XMLReaderFactory.createXMLReader();
          XMLFilter xf = new MyFilter();
          xf.setParent(xr);
          xr = xf;
          xr.parse(is);
          xr.setFeature("http://xml.org/sax/features/namespaces", true);
          DefaultHandler handler = new DefaultHandler();
          xr.setContentHandler(handler);
      }
      private class MyFilter extends XMLFilterImpl{
               StringBuffer buffer;
           int temp=0;
               int sum=0;
               String ff;
               int numof=0;
               private MyFilter() {}
  
              @Override
                  public void startDocument() throws SAXException {
                       System.out.println( "START DOCUMENT" );
                      numof=0;        
                  }
  
                  public void startElement(String namespaceURI, String localName, String  name,   Attributes attributes) throws SAXException{
                      if(localName.equals("turn")){
                          buffer=new StringBuffer();
                          }
                      if("piece".equals(name)){
                          numof++;
                      }
                  }
  
                  public void characters(char[] ch, int start, int length) throws SAXException {
                      String s=new String(ch, start, length);
                      if(buffer!=null){
                          buffer.append(s);
                          }
                  }
  
                  public void endElement(String uri, String localName, String name)throws SAXException {
                      if(buffer!=null ){
                          ff=buffer.toString();
                          temp=Integer.valueOf(ff);
                          sum=sum+temp;
                          }
                          buffer=null;
                  }
                  public void endDocument() throws SAXException {
                      System.out.println( "END DOCUMENT" );
                      System.out.println("sum of turn: "+ sum);
                      System.out.println("sum of piece: "+ numof);
                  }
           }
  
      }
  What should I do next?
  解决方案
  Your XMLFilter should delegate to another ContentHandler that serializes the document based on the sax events.
  SAXTransformerFactory factory = (SAXTransformerFactory)TransformerFactory.newInstance();
  TransformerHandler serializer = factory.newTransformerHandler();
  Result result = new StreamResult(...);
  serializer.setResult(result);
  
  XMLFilterImpl filter = new MyFilter();
  filter.setContentHandler(serializer);
  
  XMLReader xmlreader = XMLReaderFactory.createXMLReader();
  xmlreader.setFeature("http://xml.org/sax/features/namespaces", true);
  xmlreader.setFeature("http://xml.org/sax/features/namespace-prefixes", true);
  xmlreader.setContentHandler(filter);
  
  xmlreader.parse(new InputSource(...));
  Your callback should delegate to the super implementation, which forwards the events to the serializing ContentHandler.
  public void startElement(String namespaceURI, String localName, String qName, Attributes atts) throws SAXException {
      super.startElement(namespaceURI, localName, qName, atts);
      ...
  }
  In your endElement callback you can check if your are at the final closing tag and add additional sax events.
  public void endElement(String namespaceURI, String localName, String qName) throws SAXException {
      super.endElement(namespaceURI, localName, qName);
      if ("game".equals(localName)) {
          super.startElement("", "statistics", "statistics", new AttributesImpl());
          char[] chars = String.valueOf(num).toCharArray();
          super.characters(chars, 0, chars.length);
          super.endElement("", "statistics", "statistics");
      }
      ...
  }
  
  
                          
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