logfileoutputstream.java

aglet的部分源码

package com.ibm.awb.misc;

import java.util.Date;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.io.File;
import java.io.RandomAccessFile;
import java.io.OutputStream;
import java.io.IOException;

/*
 * @(#)LogFileOutputStream.java
 * 
 * IBM Confidential-Restricted
 * 
 * OCO Source Materials
 * 
 * 03L7246 (c) Copyright IBM Corp. 1996, 1998
 * 
 * The source code for this program is not published or otherwise
 * divested of its trade secrets, irrespective of what has been
 * deposited with the U.S. Copyright Office.
 */

/**
 * Write a log to a file. If the file does not exist, it will create it. If
 * a directory of the file does not exist, ir will create the directory too.
 * @author	GakuYamamoto
 */
public class LogFileOutputStream extends OutputStream {
	String _fileName = null;
	RandomAccessFile _file = null;
	long _maxFileSize = 0;

	/**
	 * Create an instance of this class. If the file does not exist, it will create
	 * the file. If a directory of the file does not exist, it will create the directory
	 * too.
	 * @param filename log file name
	 * @param maxFileSize maximum file size of the log. If the size of the log file exceeds
	 * this value, the log file will be renamed and a new log file will be created.
	 * @exception IOException if fail to create or access the file.
	 * @return an instance of this class.
	 */
	public LogFileOutputStream(String filename, 
							   long maxFileSize) throws IOException {
		checkFile(filename);
		_file = new RandomAccessFile(filename, "rw");
		_file.seek(_file.length());
		_maxFileSize = maxFileSize;
		_fileName = filename;
	}
	private RandomAccessFile changeFile(RandomAccessFile file, 
										String filename) throws Exception {
		String dstName = filename + ".arc";

		file.close();
		File src = new File(filename);
		File dst = new File(dstName);

		if (dst.exists()) {
			Calendar date = new GregorianCalendar();
			String bakName = dstName + date.get(Calendar.MINUTE) 
							 + date.get(Calendar.HOUR_OF_DAY) 
							 + date.get(Calendar.DATE) 
							 + date.get(Calendar.MONTH) 
							 + date.get(Calendar.YEAR);
			File bak = new File(bakName);

			if (bak.exists() == false) {
				dst.renameTo(bak);
			} 
		} 
		src.renameTo(dst);
		file = new RandomAccessFile(filename, "rw");
		return file;
	}
	private void checkFile(String filename) throws IOException {

		// System.out.println(filename);
		File file = new File(filename);
		File dir = new File(file.getParent());

		if (dir.exists() == false && dir.mkdir() == false) {
			throw new IOException("cannot create the directory" + dir);
		} 
		if (file.exists() && file.canWrite() == false) {
			throw new IOException("The file " + file + " is not writable");
		} 
	}
	/**
	 * Close this.
	 */
	public void close() throws IOException {
		_file.close();
		super.close();
	}
	/**
	 * Write data to the log file. If the size of the file exceeds maximum size of
	 * the file, this stream will rename the file to filename + ".arc" and create a
	 * new log file. If the file whose name is "filename + ".arc"" already exists,
	 * the existing file will be renamed to "filename + ".arc" + date.getMinutes() +
	 * date.getHours() + date.getDate() + date.getMonth() + date.getYear()", where  date
	 * is current date.
	 * @param b data.
	 * @exception IOException if fail to write the data.
	 */
	public synchronized void write(byte[] b) throws IOException {
		long pointer = _file.getFilePointer();

		if (pointer > _maxFileSize) {
			try {
				_file = changeFile(_file, _fileName);
			} catch (Exception e) {

				// e.printStackTrace();
				throw new IOException("can't create archive file." 
									  + e.toString());
			} 
		} 
		_file.write(b);
	}
	/**
	 * Write data to the log file. If the size of the file exceeds maximum size of
	 * the file, this stream will rename the file to filename + ".arc" and create a
	 * new log file. If the file whose name is "filename + ".arc"" already exists,
	 * the existing file will be renamed to "filename + ".arc" + date.getMinutes() +
	 * date.getHours() + date.getDate() + date.getMonth() + date.getYear()", where  date
	 * is current date.
	 * @param b data.
	 * @param off offset of the data.
	 * @param len length of the data written to the file.
	 * @exception IOException if fail to write the data.
	 */
	public synchronized void write(byte[] b, int off, 
								   int len) throws IOException {
		long pointer = _file.getFilePointer();

		if (pointer > _maxFileSize) {
			try {
				_file = changeFile(_file, _fileName);
			} catch (Exception e) {

				// e.printStackTrace();
				throw new IOException("can't create archive file." 
									  + e.toString());
			} 
		} 
		_file.write(b, off, len);
	}
	/**
	 * Write data to the log file. If the size of the file exceeds maximum size of
	 * the file, this stream will rename the file to filename + ".arc" and create a
	 * new log file. If the file whose name is "filename + ".arc"" already exists,
	 * the existing file will be renamed to "filename + ".arc" + date.getMinutes() +
	 * date.getHours() + date.getDate() + date.getMonth() + date.getYear()", where  date
	 * is current date.
	 * @param b integer.
	 * @exception IOException if fail to write the data.
	 */
	public synchronized void write(int b) throws IOException {
		long pointer = _file.getFilePointer();

		if (pointer > _maxFileSize) {
			try {
				_file = changeFile(_file, _fileName);
			} catch (Exception e) {

				// e.printStackTrace();
				throw new IOException("can't create archive file." 
									  + e.toString());
			} 
		} 
		_file.write(b);
	}
}