XMLのシリアライズ

「魔王なんて！」にネットワーク機能を付けようと思い必要な機能を洗い出したのですが、ログインや友達リスト等ゲームの処理に入る前にユーザー管理周りでも通信種類って結構多いのですよね。（メッセージ送信とかいろいろありますよね。）

相変わらず独りで実装しているので通信種類が増えすぎるとプログラム量がどんどん増えて管理しきれなくなるのですよね。個人でプログラムを作る場合はプログラムや処理種類を減らす工夫も大事なので、まずオブジェクトのシリアライズを検討する事にしました。これはサーバーとクライアントで同じクラスを使いたいためです。Android以外の端末にも将来展開したいので、バイナリデータで通信せずXMLが良いかなと思います。

そこで何か使えるライブラリを調べてみたのですが、どうも定義ファイルが必要なものが多いのですよね。で、実装がシンプルなものも少ないですし、ドキュメントは英語ですし。

なんだか英語のドキュメント読んでいる時間で実装できそうな気がしたので実装してみました。

XMLReaderがデシリアライズ。XMLWriterがシリアライズを行います。
key, valueで表しつつ、内部クラスも表現できる最小セットの実装かなとおもいます。

package com.cosmicdragon.darkgreen.xml;

public interface XMLDefine {

    public static final String ELEMENT_ROOT  = "d";
    public static final String ELEMENT_ROW   = "r";
    public static final String ELEMENT_CLASS = "c";
    
    public static final String ATTR_NAME     = "n";
    public static final String ATTR_VERSION  = "v";
    public static final String ATTR_KEY      = "k";
    public static final String ATTR_TYPE     = "t";
    
    public static final String TYPE_INT      = "i";
    public static final String TYPE_BOOL     = "b";
    public static final String TYPE_LONG     = "l";
    public static final String TYPE_STRING   = "s";
    public static final String TYPE_DATE     = "d";
    
}

package com.cosmicdragon.darkgreen.xml;

import java.util.Date;

public class XMLReadListener {
    public void readStart(String version){}
    public void readEnd(){}
    public void readClassStart(String name){}
    public void readClassEnd(){}
    public void readRowInt(String key, int value){}
    public void readRowLong(String key, long value){}
    public void readRowBoolean(String key, boolean value){}
    public void readRowString(String key, String value){}
    public void readRowDate(String key, Date value){}
}

package com.cosmicdragon.darkgreen.xml;

import java.io.IOException;
import java.util.Date;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.ParserConfigurationException;
import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.helpers.DefaultHandler;

public class XMLReader implements XMLDefine {
    private SAXParser parser = null;
    private Handler hdl = new Handler();
    
    public void readXML(XMLReadListener listener, InputSource is)
    throws ParserConfigurationException, SAXParseException, SAXException, IOException{
        hdl.reset(listener);
        
        if(parser == null){
            parser = SAXParserFactory.newInstance().newSAXParser();
        }
        
        parser.parse(is, hdl);
        if(hdl.getException() != null)throw hdl.getException();
        
        hdl.reset(null);
    }
}

class Handler extends DefaultHandler {
    private SAXParseException exception;
    private XMLReadListener listener;
    
    private boolean rowFlag = false;
    private String rowType = "";
    private String rowKey  = "";
    private String rowValue= "";

    public void reset(XMLReadListener listener){
        this.listener  = listener;
        this.exception = null;
    }
    
    public SAXParseException getException(){
        return this.exception;
    }
    
    public void startElement(String uri, String localName, String qName, Attributes atts)
    throws SAXException {
        rowFlag = false;
        if(qName.equals(XMLDefine.ELEMENT_ROOT)){
            listener.readStart(atts.getValue(XMLDefine.ATTR_VERSION));
        }else if(qName.equals(XMLDefine.ELEMENT_CLASS)){
            listener.readClassStart(atts.getValue(XMLDefine.ATTR_NAME));
        }else if(qName.equals(XMLDefine.ELEMENT_ROW)){
            rowFlag = true;
            rowValue = "";
            rowType = atts.getValue(XMLDefine.ATTR_TYPE);
            rowKey  = atts.getValue(XMLDefine.ATTR_KEY);
            System.out.println("startElement() : " + rowType + " : " + rowKey);
        }
    }
    
    public void endElement(String uri, String localName, String qName)
    throws SAXException {
        if(qName == XMLDefine.ELEMENT_ROOT){
            listener.readEnd();
        }else if(qName == XMLDefine.ELEMENT_CLASS){
            listener.readClassEnd();
        }else if(qName == XMLDefine.ELEMENT_ROW){
            if(rowType.equals(XMLDefine.TYPE_INT))
                listener.readRowInt(rowKey, Integer.parseInt(rowValue));
            else if (rowType.equals(XMLDefine.TYPE_LONG))
                listener.readRowLong(rowKey, Long.parseLong(rowValue));
            else if (rowType.equals(XMLDefine.TYPE_BOOL))
                listener.readRowBoolean(rowKey, Boolean.parseBoolean(rowValue));
            else if (rowType.equals(XMLDefine.TYPE_STRING))
                listener.readRowString(rowKey, rowValue);
            else if (rowType.equals(XMLDefine.TYPE_DATE))
                listener.readRowDate(rowKey, new Date(Long.parseLong(rowValue)));
        }
    }
    
    public void characters(char[] ch, int start, int length)
    throws SAXException {
        if(rowFlag)
            rowValue += String.copyValueOf(ch, start, length);
    }
    
    public void error(SAXParseException e) {
        exception = e;
    }
    
    public void fatalError(SAXParseException e) {
        exception = e;
    }

}

package com.cosmicdragon.darkgreen.xml;

import java.io.PrintStream;
import java.util.Date;

public class XMLWriter implements XMLDefine {

    private int tabNum;
    
    //---------------------------------------- write APIs.
    public final void writeStartDocument(PrintStream out){
        writeStartDocument(out, "UTF-8", "1.0");
    }
    
    public final void writeStartDocument(PrintStream out, String encode, String version){
        tabNum = 0;
        out.print("<?xml version=\"1.0\" encoding=\""
                + encode +"\"?>");
        out.print("\n");
        out.print("<" + ELEMENT_ROOT
                + " " + ATTR_VERSION  + "=\"" + version  + "\""
                + ">");
        out.print("\n");
        tabNum = 1;
    }

    public final void writeEndDocument(PrintStream out){
        out.print("</" + ELEMENT_ROOT + ">");
    }

    public final void writeStartClass(PrintStream out, String name){
        writeTab(out);
        out.print("<" + ELEMENT_CLASS 
                + " " + ATTR_NAME  + "=\"" + name  + "\""
                + ">");
        out.print("\n");
        tabNum++;
    }

    public final void writeEndClass(PrintStream out){
        tabNum--;
        writeTab(out);
        out.print("</" + ELEMENT_CLASS + ">");
        out.print("\n");
    }
    
    public final void writeInt(PrintStream out, String key, int v) {
        writeRowStart(out, key, TYPE_INT);
        out.print(v);
        writeRowEnd(out);
    }

    public final void writeBoolean(PrintStream out, String key, boolean v){
        writeRowStart(out, key, TYPE_BOOL);
        out.print(v);
        writeRowEnd(out);
    }

    public final void writeLong(PrintStream out, String key, long v){
        writeRowStart(out, key, TYPE_LONG);
        out.print(v);
        writeRowEnd(out);
    }

    public final void writeString(PrintStream out, String key, String v){
        writeRowStart(out, key, TYPE_STRING);
        out.print(v);
        writeRowEnd(out);
    }
    
    public final void writeDate(PrintStream out, String key, Date v){
        writeRowStart(out, key, TYPE_DATE);
        out.print(v.getTime());
        writeRowEnd(out);
    }

    private final void writeRowStart(PrintStream out, String key, String type){
        writeTab(out);
        out.print("<" + ELEMENT_ROW 
                + " " + ATTR_KEY  + "=\"" + key  + "\""
                + " " + ATTR_TYPE + "=\"" + type + "\""
                + ">");
    }
    
    private final void writeRowEnd(PrintStream out){
        out.print("</" + ELEMENT_ROW  + ">");
        out.print("\n");
    }
    
    private final void writeTab(PrintStream out){
        for(int i=0; i<this.tabNum; i++) out.print('\t');
    }
}

テストプログラムを簡単ですが書いてみました。PersonクラスをいったんXMLに出力して、XML文字列からクラスを復元しています。

import java.io.IOException;
import java.io.ByteArrayOutputStream;
import java.io.ByteArrayInputStream;
import java.io.PrintStream;

import java.util.Date;

import javax.xml.parsers.ParserConfigurationException;

import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

import junit.framework.TestCase;

import com.cosmicdragon.darkgreen.xml.XMLReader;
import com.cosmicdragon.darkgreen.xml.XMLWriter;
import com.cosmicdragon.darkgreen.xml.XMLReadListener;

public class Test01 extends TestCase {

    public void testA(){
        ByteArrayOutputStream buff = new ByteArrayOutputStream();
        PrintStream print = new PrintStream(buff);
        PersonSerializer serial = new PersonSerializer();

        Person p1 = new Person("hero", 18, true);
        
        try{Thread.sleep(2000);}catch(Exception e){}
        
        Person p2 = new Person("lynn", 17, false);
        
        
        System.out.println("p1: " + p1);
        System.out.println("p2: " + p2);
        
        serial.writeXML(print, p1);
        System.out.println(buff.toString());
        
        try{
            serial.readXML(buff.toByteArray(), p2);
        }catch(Exception e){
            e.printStackTrace();
        }

        System.out.println("p1: " + p1);
        System.out.println("p2: " + p2);

        super.assertEquals(p1.age, p2.age);
        super.assertEquals(p1.name, p2.name);
        super.assertEquals(p1.flag, p2.flag);
        super.assertEquals(p1.date.getTime(), p2.date.getTime());
    }
}

class Person extends XMLWriter {
    int age;
    String name;
    boolean flag;
    Date date;
    
    public Person(String name, int age, boolean flag){
        this.name = name;
        this.age  = age;
        this.flag = flag;
        this.date = new Date();
    }
    
    public String toString(){
        return "Person : " 
            + "age:" + age
            + ":name:" + name
            + ":flag:" + flag
            + ":date:" + date
        ;
    }
}

class PersonSerializer extends XMLReadListener {
    Person p;
    
    public void writeXML(PrintStream out, Person p){
        XMLWriter writer = new XMLWriter();
        writer.writeStartDocument(out);
        writer.writeStartClass(out, "Person");
        writer.writeString(out, "name", p.name);
        writer.writeInt(out, "age", p.age);
        writer.writeBoolean(out, "flag", p.flag);
        writer.writeDate(out, "date", p.date);
        writer.writeEndClass(out);
        writer.writeEndDocument(out);
    }
    
    public void readXML(byte[] in, Person p) 
    throws ParserConfigurationException, SAXException, IOException{
        this.p = p;
        InputSource src = new InputSource(new ByteArrayInputStream(in));
        XMLReader reader = new XMLReader();
        reader.readXML(this, src);
    }
    
    public void readRowInt(String key, int value){
        p.age = value; 
    }

    public void readRowBoolean(String key, boolean value){
        p.flag = value; 
    }
    
    public void readRowString(String key, String value){
        p.name = value; 
    }
    
    public void readRowDate(String key, Date value){
        p.date = value; 
    }
}

下記は実行結果です。p1をシリアライズしてp2にデシリアライズをしています。

p1: Person : age:18:name:hero:flag:true:date:Thu Sep 02 01:15:23 JST 2010
p2: Person : age:17:name:lynn:flag:false:date:Thu Sep 02 01:15:25 JST 2010
<?xml version="1.0" encoding="UTF-8"?>
<d v="1.0">
 <c n="Person">
  <r k="name" t="s">hero</r>
  <r k="age" t="i">18</r>
  <r k="flag" t="b">true</r>
  <r k="date" t="d">1283357723441</r>
 </c>
</d>
p1: Person : age:18:name:hero:flag:true:date:Thu Sep 02 01:15:23 JST 2010
p2: Person : age:18:name:hero:flag:true:date:Thu Sep 02 01:15:23 JST 2010