filestreamstorage.java

Java的面向对象数据库系统的源代码

// You can redistribute this software and/or modify it under the terms of
// the Ozone Core License version 1 published by ozone-db.org.
//
// Copyright (C) 2003-@year@, Leo Mekenkamp. All rights reserved.
//
// $Id: FileStreamStorage.java,v 1.1 2004/01/02 09:24:38 leomekenkamp Exp $

package org.ozoneDB.core.storage.gammaStore;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.math.BigInteger;

/**
 * @author <a href="mailto:leoATmekenkampD0Tcom">Leo Mekenkamp (mind the anti sp@m)</a>
 * @version $Id $
 */
public class FileStreamStorage extends AbstractStorage {
    
    private DataInputStream in = null;
    private DataOutputStream out = null;
    private File file;
    
    FileStreamStorage(File file) throws IOException {
        this.file = file;
    }
    
    private void checkForWrite() throws IOException {
        if (out == null) {
            out = new DataOutputStream(new FileOutputStream(file));
        }
    }

    private void checkForRead() throws IOException {
        if (in == null) {
            in = new DataInputStream(new FileInputStream(file));
        }
    }

    public void setLength(long length) throws IOException {
        throw new UnsupportedOperationException("not supported in FileStreamStorage");
    }
    
    public void seek(long pos) throws IOException {
        throw new UnsupportedOperationException("not supported in FileStreamStorage");
    }
    
    public void readFully(byte[] b, int offset, int length) throws IOException {
        checkForRead();
        in.readFully(b, offset, length);
    }
    
    public void write(byte[] b, int offset, int length) throws IOException {
        checkForWrite();
        out.write(b, offset, length);
        out.flush();
    }
    
    public long readLong() throws IOException {
        checkForRead();
        return in.readLong();
    }
    
    public void writeLong(long value) throws IOException {
        checkForWrite();
        out.writeLong(value);
        out.flush();
    }
    
    public void close() throws IOException {
        try {
            if (in != null) {
                in.close();
            }
        } finally {
            if (out != null) {
                out.close();
            }
        }
    }
    
    public long length() throws IOException {
        return file.length();
    }
    
    public int readInt() throws IOException {
        checkForRead();
        return in.readInt();
    }
    
    public void writeInt(int value) throws IOException {
        checkForWrite();
        out.writeInt(value);
        out.flush();
    }
    
}