使用SAX解析器构建XML文件

2 回答

• 0

  您可以使用XMLFilterImpl并只保留您需要的内容，这里有一个想法，输入和输出都是流，因此它可以处理任何大小的XML

  XMLReader xr = new XMLFilterImpl(XMLReaderFactory.createXMLReader()) {
          public void startElement(String uri, String localName, String qName, Attributes atts)
                  throws SAXException {
              if (qName.equals("page")) {
                  super.startElement(uri, localName, qName, atts);
              }
          }
  
          public void endElement(String uri, String localName, String qName) throws SAXException {
              if (qName.equals("page")) {
                  super.endElement(uri, localName, qName);
              }
          }
  
          public void characters(char[] ch, int start, int length) throws SAXException {
              //super.characters(ch, start, length);
          }
      };
      Source src = new SAXSource(xr, new InputSource("1.xml"));
      Result res = new StreamResult(System.out);
      TransformerFactory.newInstance().newTransformer().transform(src, res);
  

  回复于 2024-04-19T20:30:59+08:00
• 2

  在这里，我使用SAX Parser实现解析，提取 Headers 元素和 Headers

  维基百科转储文件中的重定向元素中的属性 .

  package parser;
  
  import java.io.File;
  import java.io.FileWriter;
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.List;
  
  import javax.xml.parsers.ParserConfigurationException;
  import javax.xml.parsers.SAXParser;
  import javax.xml.parsers.SAXParserFactory;
  
  import org.xml.sax.Attributes;
  import org.xml.sax.SAXException;
  import org.xml.sax.helpers.DefaultHandler;
  
  
  
   public class SAXHandler extends DefaultHandler {
  
  List<String> list;
  int count=0,counter=0;
  int MAX_SIZE=100000;
  String temp="";
  int counterz=0;
  public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException{
  
          long start = System.currentTimeMillis();            
  
          SAXHandler saxhandler=new SAXHandler();
          saxhandler.assign();
          saxhandler.parseDoc();
  
          long end = System.currentTimeMillis();
          System.out.println("Time taken to write is " + (end - start) + "msecs");    
  
  }
  
  void assign(){
      list = new ArrayList<String>(); 
  }
  
  void parseDoc() throws ParserConfigurationException, SAXException, IOException{
  
      SAXParserFactory spf = SAXParserFactory.newInstance();
      SAXParser sp = spf.newSAXParser();
      sp.parse("D:\\XMLParsing_Files\\enwiki-20120902-pages-articles-multistream.xml", this);
      writeToFile(list); // for writing the end elements
  }
  
  public void startDocument() throws SAXException {
  
  }
  
  public void endDocument() throws SAXException {
  
  }
  
  public void startElement(String uri, String localName,String qName, Attributes attributes)throws SAXException {
  
      if(qName.equalsIgnoreCase("redirect"))
      {
          list.add(attributes.getValue("title"));
          count++;
          if(count==MAX_SIZE)
          {
              try {
                  writeToFile(list);
              } catch (IOException e) {
                  e.printStackTrace();
              }
              list.clear();
              count=0;
          }
      }
  
  }
  
  public void endElement(String uri, String localName, String qName)throws SAXException {
  
     if(qName.equalsIgnoreCase("title"))
     {
         list.add(temp);
         count++;
         if(count==MAX_SIZE)
         {
          try {
              writeToFile(list);
          } catch (IOException e) {
              e.printStackTrace();
          }
          list.clear();
          count=0;
         }
     }
  
  }
  
  public void characters(char ch[], int start, int length)throws SAXException {
  
      temp="";
      temp=new String(ch,start,length);
  }
  
  void writeToFile(List<String> list) throws IOException{
  
      Collections.sort(list);
      File file = new File("D:\\XMLParsing_Files\\Extracted_Data\\Extracted_Sorted_Data_" + getSuffix() + ".txt");
  
  
      if (!file.exists()) {
          file.createNewFile();
      }
  
      FileWriter fw = new FileWriter(file.getAbsoluteFile());
      PrintWriter pw = new PrintWriter(fw);
  
      Iterator<String> it = list.iterator();
      while (it.hasNext()) {
          pw.println(it.next());
      }
      pw.println("zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz");   
      pw.close();
      System.out.println(++counterz + "Done");
  }
  
  int  getSuffix(){
      counter++;
      return counter;
   }
  
  }
  

  回复于 2024-04-19T20:30:59+08:00