XMLはSAX方式で解析する

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xml

詳細
1.XMLはSAX方式で解析


SAX                    ，      (document)     、  (element)     、  (document)              ，            ，         ，      。
  ：       ；       ；
  ：        ；    ；

1.1 SAX方式でXMLファイルを読み込む


package com.andrew.xml;
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 SAX01 extends DefaultHandler {
    @Override
    public void startDocument() throws SAXException {
        System.out.println("");
    }
    @Override
    public void endDocument() throws SAXException {
        System.out.print("
       ");
    }
    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        System.out.print("");
    }
    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        System.out.print("");
        System.out.print(qName);
        System.out.print(">");
    }
    @Override
    public void characters(char[] ch, int start, int length) throws SAXException {
        System.out.print(new String(ch, start, length));
    }

    public static void main(String[] args) throws Exception {
        SAXParserFactory factory = SAXParserFactory.newInstance();
        SAXParser parser = factory.newSAXParser();
        parser.parse("src/students.xml", new SAX01());
    }
}
    ：


    
          
         
        20
    
    
          
         
        21

1.2 SAX方式でXMLデータをBeanに読み出す


package com.andrew.model;
public class Student {
    private String id;
    private String name;
    private String sex;
    private int age;
    @Override
    public String toString() {
        return "Student [id=" + id + ", name=" + name + ", sex=" + sex + ", age=" + age + "]";
    }
    // getter and setter
}


package com.andrew.xml;
import java.util.ArrayList;
import java.util.List;
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;
import com.andrew.model.Student;
public class SAX02 extends DefaultHandler {
    private List students = null;
    private Student student = null;
    private String preTag = null; //          
    @Override
    public void startDocument() throws SAXException {
        System.out.println("        ");
        students = new ArrayList();
    }
    @Override
    public void endDocument() throws SAXException {
        System.out.println("        ");
    }
    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        if ("student".equals(qName)) {
            student = new Student();
            student.setId(attributes.getValue(0));
        }
        preTag = qName;
    }
    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        if ("student".equals(qName)) {
            students.add(student);
            student = null;
        }
        preTag = null;
    }
    @Override
    public void characters(char[] ch, int start, int length) throws SAXException {
        if (preTag != null) {
            String content = new String(ch, start, length);
            if ("name".equals(preTag)) {
                student.setName(content);
            } else if ("sex".equals(preTag)) {
                student.setSex(content);
            } else if ("age".equals(preTag)) {
                student.setAge(Integer.parseInt(content));
            }
        }
    }
    public static void main(String[] args) throws Exception {
        SAXParserFactory factory = SAXParserFactory.newInstance();
        SAXParser parser = factory.newSAXParser();
        SAX02 sax02 = new SAX02();
        parser.parse("src/studentsSax.xml", sax02);
        for (Student s : sax02.students) {
            System.out.println(s);
        }
    }
}

    ：
        
        
Student [id=001, name=  , sex= , age=20]
Student [id=002, name=  , sex= , age=21]

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