java.nio vs java.io

早々コードね．ダンプ用のコードだけどちょっといじればランダム用もできる．
ランダムのほうはごちゃごちゃ混ざっているので，ちょっと勘弁して(汗

• java.io のほうのコード

import java.io.IOException;
import java.io.RandomAccessFile;

public class Bin2Txt {
    public static final int LONG_SIZE = 8;
    public static final int DATA_SIZE = 4 + 8;

    public static void main(String[] args) throws IOException {
        if(args.length != 2) {
            System.err.println("java Bin2Txt <index file> <data file>");
            System.exit(-1);
        }
        String indexfile = args[0];
        String datafile = args[1];

        RandomAccessFile index = new RandomAccessFile(indexfile, "r");
        RandomAccessFile data = new RandomAccessFile(datafile, "r");
        long size = index.length() / LONG_SIZE - 1;
        long offset, length;
        for(int i = 0; i < size; ++i) {
            index.seek(i * LONG_SIZE);
            offset = index.readLong();
            length = index.readLong();
            data.seek(offset);
            while(offset < length) {
                System.out.println(i + " " + data.readInt() + " " + data.readDouble());
                offset += DATA_SIZE;
            }
        }
        data.close();
        index.close();
    }
}

• java.nio のほうのコード

import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.LongBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;

public class Bin2Txt2 {
    public static final int LONG_SIZE = 8;
    public static final int DATA_SIZE = 4 + 8;

    public static void main(String[] args) throws IOException {
        if(args.length != 2) {
            System.err.println("java Bin2Txt2 <index file> <data file>");
            System.exit(-1);
        }
        String indexfile = args[0];
        String datafile = args[1];

        FileChannel indexchannel = new FileInputStream(indexfile).getChannel();
        FileChannel datachannel = new FileInputStream(datafile).getChannel();
        
        LongBuffer indexbuf = indexchannel.map(MapMode.READ_ONLY, 0, indexchannel.size()).asLongBuffer();
        ByteBuffer databuf = datachannel.map(MapMode.READ_ONLY, 0, datachannel.size());
        
        long size = indexchannel.size() / LONG_SIZE - 1;
        long offset, length;
        for(int i = 0; i < size; ++i) {
            indexbuf.position(i);
            offset = indexbuf.get();
            length = indexbuf.get();
            databuf.position((int)offset);
            while(offset < length) {
                System.out.println(i + " " + databuf.getInt() + " " + databuf.getDouble());
                offset += DATA_SIZE;
            }
        }
        datachannel.close();
        indexchannel.close();
    }
}

• これはデータを作成するほう．こっちは別にnioは使ってない．

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.regex.Pattern;

public class Txt2Bin {
    private static final Pattern p = Pattern.compile("\\s+");
    public static void main(String[] args) throws IOException {
        if(args.length != 3) {
            System.err.println("java Txt2Bin <in file> <out index file> <out data file>");
            System.exit(-1);
        }
        File infile = new File(args[0]);
        File indexfile = new File(args[1]);
        File datafile = new File(args[2]);
        if(indexfile.exists()) {
            System.err.println("delete file: " +indexfile);
            indexfile.delete();
        }
        if(datafile.exists()) {
            System.err.println("delete file: " +datafile);
            datafile.delete();
        }

        int last = 0;     
        BufferedReader br = new BufferedReader(new FileReader(infile));
        RandomAccessFile index = new RandomAccessFile(indexfile, "rw");
        RandomAccessFile data  = new RandomAccessFile(datafile, "rw");
        
        while(br.ready()) {
            String[] f = p.split(br.readLine());
            int i = Integer.parseInt(f[0]), j = Integer.parseInt(f[1]);
            double d = Double.parseDouble(f[2]);
            long locate = data.getFilePointer();
            while(last <= i) {
                index.writeLong(locate);
                ++last;
            }
            data.writeInt(j);
            data.writeDouble(d);
        }
        index.writeLong(data.getFilePointer());
        
        data.close();
        index.close();
        br.close();
    }
}