Streaming API for XML

Java SE STaX ( Streaming API for XML ) example

Java SE 6부터 제공되는 ATaX 를 이용하여 XML파일의 데이터를 읽고 쓰는 예제이다. STaX는 기존의 방법인 SAX, DOM 방식을 대체할 새로운 방법이다. XML파일을 읽을 때는 XMLEventReader를 이용하고 XML 파일에 기록할 때는 XMLEventWriter를 이용한다.

ATax는 2가지 방법으로 접근할 수 있다. Cursor나 Event Iterator를 이용하여 접근할 수 있으며 여기서는 더 편리한 Event Iterator 방식을 소개한다. 

STaX방법은 기존 API(SAX, DOM)와는 달리 개발자의 응용프로그램에서 파서를 충분히 제어할 수 있는 특징을 가지고 있다.

Android에서 XML을 다루기 위한 XmlPullParser와 같은 특징을 가지고 있다고 할 수 있겠다. 그리고 XML문서를 파일에 저장할 수 있는 API, XMLEventWriter도 제공되는데 개행문자(\n")와 탭문자(\t)는 자동으로 추가되지 않으므로 필요한 곳에 개발자가 직접 언급해 주어야 한다.

Android 에서도 이와 유사한 XmlPullParser가 제공된다. 여기를 참조하세요

D:/test/student.xml ( STaX를 사용하여 파싱할 XML 파일의 내용 )

<?xml version="1.0" encoding="EUC-KR"?>
<course>
	<student id="11">
		<name>김사랑</name>
		<phone>010-3456-7654</phone>
		<email>sarang@naver.com</email>
		<birth_date>1980-11-20</birth_date>
	</student>
	<student id="12">
		<name>이수복</name>
		<phone>010-5687-6345</phone>
		<email>suboklee@yahoo.com</email>
		<birth_date>1980-11-20</birth_date>
	</student>
	<student id="13">
		<name>박진수</name>
		<phone>010-7689-7544</phone>
		<email>jinsupark@gmail.com</email>
		<birth_date>1980-11-20</birth_date>
	</student>
</course> 

Student.java ( 읽어온 XML 문서의 내용을 저장할 클래스 )

package com.example.xml;

public class Student {
	
	private int id;
	private String name;
	private String phone;
	private String email;
	private String birthDate;
	
	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getPhone() {
		return phone;
	}

	public void setPhone(String phone) {
		this.phone = phone;
	}

	public String getEmail() {
		return email;
	}

	public void setEmail(String email) {
		this.email = email;
	}

	public String getBirthDate() {
		return birthDate;
	}

	public void setBirthDate(String birth_date) {
		this.birthDate = birth_date;
	}

	@Override
	public String toString() {
		return "Student [id=" + id + ", name=" + name + ", phone="
				+ phone + ", email=" + email + ", birth date=" + birthDate+"]";
	}
}

StaxReader.java ( STaX 를 이용하여 XML 문서의 내용을 읽어오면서 Student 객체에 저장한다 )

package com.example.xml;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import javax.xml.stream.XMLEventReader;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.events.Attribute;
import javax.xml.stream.events.EndElement;
import javax.xml.stream.events.StartElement;
import javax.xml.stream.events.XMLEvent;

public class StaxReader {

	public List<Student> readStudent(String filePath) {
		List<Student> items = new ArrayList<Student>();
		try {
			// First create a new XMLInputFactory
			XMLInputFactory inputFactory = XMLInputFactory.newInstance();
			// Setup a new eventReader
			InputStream in = new FileInputStream(filePath);
			XMLEventReader eventReader = inputFactory.createXMLEventReader(in);
			// Read the XML document
			Student student = null;

			while (eventReader.hasNext()) {
				XMLEvent event = eventReader.nextEvent();
				//if(event.isStartDocument()){xxxx};
				if (event.isStartElement()) {
					StartElement startElement = event.asStartElement();
					// If we have a item element we create a new item
					if (startElement.getName().getLocalPart().equals("student")) {
						student = new Student();
						// We read the attributes from this tag and add the date
						// attribute to our object
						Iterator<Attribute> attributes = startElement
								.getAttributes();
						while (attributes.hasNext()) {
							Attribute attribute = attributes.next();
							if (attribute.getName().toString().equals("id")) {
								student.setId(Integer.valueOf(attribute.getValue()));
							}

						}
					}

					if (event.isStartElement()) {
						if (event.asStartElement().getName().getLocalPart()
								.equals("name")) {
							event = eventReader.nextEvent();
							student.setName(event.asCharacters().getData());
							continue;
						}
					}
					if (event.asStartElement().getName().getLocalPart()
							.equals("phone")) {
						event = eventReader.nextEvent();
						student.setPhone(event.asCharacters().getData());
						continue;
					}

					if (event.asStartElement().getName().getLocalPart()
							.equals("email")) {
						event = eventReader.nextEvent();
						student.setEmail(event.asCharacters().getData());
						continue;
					}

					if (event.asStartElement().getName().getLocalPart()
							.equals("birth_date")) {
						event = eventReader.nextEvent();
						student.setBirthDate(event.asCharacters().getData());
						continue;
					}
				}
				// If we reach the end of an item element we add it to the list
				if (event.isEndElement()) {
					EndElement endElement = event.asEndElement();
					if (endElement.getName().getLocalPart().equals("student")) {
						items.add(student);
					}
				}
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (XMLStreamException e) {
			e.printStackTrace();
		}
		return items;
	}

	public static void main(String[] args) {
		StaxReader reader = new StaxReader();
		List<Student> list = reader.readStudent("d:/test/student.xml");
		for (Student item : list) {
			System.out.println(item);
		}
	}
}

다음은 XMLEventWriter 를 이용한 XML문서의 파일저장 예이다

개행문자(\n), 탭문자(\t)는 자동으로 추가되지 않으므로 개발자가 직접 언급해주어야 한다.

D:/test/student2.xml ( XMLEventWriter를 이용하여 파일에 저장할 내용 )

<?xml version="1.0"?>
<course>
	<student id="11">
		<name>김순정</name>
		<phone>010-4576-8654</phone>
		<email>sunjung@yahoo.com</email>
		<birth_date>1980-01-02</birth_date>
	</student>
</course>

StaxWriter.java

package com.example.xml;

import java.io.FileOutputStream;
import java.util.ArrayList;

import javax.xml.stream.XMLEventFactory;
import javax.xml.stream.XMLEventWriter;
import javax.xml.stream.XMLOutputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.events.Attribute;
import javax.xml.stream.events.Characters;
import javax.xml.stream.events.EndElement;
import javax.xml.stream.events.StartDocument;
import javax.xml.stream.events.StartElement;
import javax.xml.stream.events.XMLEvent;

public class StaxWriter {

   public void saveStudent() throws Exception {
	// Create a XMLOutputFactory
	XMLOutputFactory outputFactory = XMLOutputFactory.newInstance();
	// Create XMLEventWriter
	XMLEventWriter eventWriter = outputFactory
			.createXMLEventWriter(new FileOutputStream("D:/test/student2.xml"));
	// Create a EventFactory
	XMLEventFactory eventFactory = XMLEventFactory.newInstance();
	XMLEvent end = eventFactory.createDTD("\n");
	XMLEvent tab = eventFactory.createDTD("\t");

	// Create and write Start Tag
	StartDocument startDocument = eventFactory.createStartDocument();
	eventWriter.add(startDocument);
	eventWriter.add(end);
	
	// Create course open tag
	StartElement rootStartElement = eventFactory.createStartElement("", "", "course");
	eventWriter.add(rootStartElement);
	eventWriter.add(end);

	Attribute attr = eventFactory.createAttribute("id", "11");
	ArrayList<Attribute> attrList = new ArrayList<Attribute>();
	attrList.add(attr);
	
	
	StartElement stdStartElement = eventFactory.createStartElement("", "", "student", attrList.iterator(), null);
	eventWriter.add(tab);
	eventWriter.add(stdStartElement);
	eventWriter.add(end);
	
	// Write the different nodes
	createNode(eventWriter, "name", "김순정");
	createNode(eventWriter, "phone", "010-4576-8654");
	createNode(eventWriter, "email", "sunjung@yahoo.com");
	createNode(eventWriter, "birth_date", "1980-01-02");

	eventWriter.add(tab);
	eventWriter.add(eventFactory.createEndElement("", "", "student"));
	eventWriter.add(end);
		
	eventWriter.add(eventFactory.createEndElement("", "", "course"));
	eventWriter.add(end);
	eventWriter.add(eventFactory.createEndDocument());
	eventWriter.close();
   }

   private void createNode(XMLEventWriter eventWriter, String name, String value) throws XMLStreamException {

	XMLEventFactory eventFactory = XMLEventFactory.newInstance();
	XMLEvent end = eventFactory.createDTD("\n");
	XMLEvent tab = eventFactory.createDTD("\t");
	// Create Start node
	StartElement sElement = eventFactory.createStartElement("", "", name);
	eventWriter.add(tab);eventWriter.add(tab);
	eventWriter.add(sElement);
	// Create Content
	Characters characters = eventFactory.createCharacters(value);
	eventWriter.add(characters);
	// Create End node
	EndElement eElement = eventFactory.createEndElement("", "", name);
	eventWriter.add(eElement);
	eventWriter.add(end);
   }

   public static void main(String[] args) throws Exception {
	StaxWriter writer = new StaxWriter();
	writer.saveStudent();
        System.out.println("XML파일 생성 성공");
   }
}