filehandler.java

java源代码 请看看啊 提点宝贵的意见

/*
 * @(#)FileHandler.java	1.26 03/01/23
 *
 * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package java.util.logging;

import java.io.*;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
import java.security.*;

/**
 * Simple file logging <tt>Handler</tt>.
 * <p>
 * The <tt>FileHandler</tt> can either write to a specified file,
 * or it can write to a rotating set of files.  
 * <p>
 * For a rotating set of files, as each file reaches a given size
 * limit, it is closed, rotated out, and a new file opened.
 * Successively older files are named by adding "0", "1", "2", 
 * etc into the base filename.
 * <p>
 * By default buffering is enabled in the IO libraries but each log
 * record is flushed out when it is complete. 
 * <p>
 * By default the <tt>XMLFormatter</tt> class is used for formatting.
 * <p>
 * <b>Configuration:</b>
 * By default each <tt>FileHandler</tt> is initialized using the following
 * <tt>LogManager</tt> configuration properties.  If properties are not defined
 * (or have invalid values) then the specified default values are used.
 * <ul>
 * <li>   java.util.logging.FileHandler.level 
 *	  specifies the default level for the <tt>Handler</tt>
 *	  (defaults to <tt>Level.ALL</tt>).
 * <li>   java.util.logging.FileHandler.filter 
 * 	  specifies the name of a <tt>Filter</tt> class to use
 *	  (defaults to no <tt>Filter</tt>).
 * <li>   java.util.logging.FileHandler.formatter 
 *	  specifies the name of a </tt>Formatter</tt> class to use
 *        (defaults to <tt>java.util.logging.XMLFormatter</tt>)
 * <li>   java.util.logging.FileHandler.encoding 
 *	  the name of the character set encoding to use (defaults to
 *	  the default platform encoding).
 * <li>   java.util.logging.FileHandler.limit 
 *	  specifies an approximate maximum amount to write (in bytes)
 * 	  to any one file.  If this is zero, then there is no limit.
 *	  (Defaults to no limit).
 * <li>   java.util.logging.FileHandler.count 
 *	  specifies how many output files to cycle through (defaults to 1).
 * <li>   java.util.logging.FileHandler.pattern 
 *	  specifies a pattern for generating the output file name.  See
 *        below for details. (Defaults to "%h/java%u.log").
 * <li>   java.util.logging.FileHandler.append
 *	  specifies whether the FileHandler should append onto
 *        any existing files (defaults to false).
 * </ul>
 * <p>
 * <p>
 * A pattern consists of a string that includes the following special
 * components that will be replaced at runtime:
 * <ul>
 * <li>    "/"    the local pathname separator 
 * <li>     "%t"   the system temporary directory
 * <li>     "%h"   the value of the "user.home" system property
 * <li>     "%g"   the generation number to distinguish rotated logs
 * <li>     "%u"   a unique number to resolve conflicts
 * <li>     "%%"   translates to a single percent sign "%"
 * </ul>
 * If no "%g" field has been specified and the file count is greater
 * than one, then the generation number will be added to the end of
 * the generated filename, after a dot.
 * <p> 
 * Thus for example a pattern of "%t/java%g.log" with a count of 2
 * would typically cause log files to be written on Solaris to 
 * /var/tmp/java0.log and /var/tmp/java1.log whereas on Windows 95 they
 * would be typically written to to C:\TEMP\java0.log and C:\TEMP\java1.log
 * <p> 
 * Generation numbers follow the sequence 0, 1, 2, etc.
 * <p>
 * Normally the "%u" unique field is set to 0.  However, if the <tt>FileHandler</tt>
 * tries to open the filename and finds the file is currently in use by
 * another process it will increment the unique number field and try
 * again.  This will be repeated until <tt>FileHandler</tt> finds a file name that
 * is  not currently in use. If there is a conflict and no "%u" field has
 * been specified, it will be added at the end of the filename after a dot.
 * (This will be after any automatically added generation number.)
 * <p>
 * Thus if three processes were all trying to log to fred%u.%g.txt then 
 * they  might end up using fred0.0.txt, fred1.0.txt, fred2.0.txt as
 * the first file in their rotating sequences.
 * <p>
 * Note that the use of unique ids to avoid conflicts is only guaranteed
 * to work reliably when using a local disk file system.
 *
 * @version 1.26, 01/23/03
 * @since 1.4
 */

public class FileHandler extends StreamHandler {
    private MeteredStream meter;
    private boolean append;
    private int limit;       // zero => no limit.
    private int count;
    private String pattern;
    private String lockFileName;
    private FileOutputStream lockStream;
    private File files[];
    private static final int MAX_LOCKS = 100;
    private static java.util.HashMap locks = new java.util.HashMap();

    // A metered stream is a subclass of OutputStream that
    //   (a) forwards all its output to a target stream
    //   (b) keeps track of how many bytes have been written
    private class MeteredStream extends OutputStream {
  	OutputStream out;
	int written;

	MeteredStream(OutputStream out, int written) {
	    this.out = out;
	    this.written = written;
	}

	public void write(int b) throws IOException {
	    out.write(b);
	    written++;
	}

	public void write(byte buff[]) throws IOException {
	    out.write(buff);
	    written += buff.length;
	}
	
	public void write(byte buff[], int off, int len) throws IOException {
	    out.write(buff,off,len);
	    written += len;
	}
	
	public void flush() throws IOException {
	    out.flush();
	}

	public void close() throws IOException {
	    out.close();
	}
    }

    private void open(File fname, boolean append) throws IOException {
	int len = 0;
	if (append) {
	    len = (int)fname.length();
	}
	FileOutputStream fout = new FileOutputStream(fname.toString(), append);
	BufferedOutputStream bout = new BufferedOutputStream(fout);
	meter = new MeteredStream(bout, len);
	setOutputStream(meter);
    }

    // Private method to configure a FileHandler from LogManager
    // properties and/or default values as specified in the class
    // javadoc.
    private void configure() {
        LogManager manager = LogManager.getLogManager();

	String cname = FileHandler.class.getName();

	pattern = manager.getStringProperty(cname + ".pattern", "%h/java%u.log");
	limit = manager.getIntProperty(cname + ".limit", 0);
	if (limit < 0) {
	    limit = 0;
	}
        count = manager.getIntProperty(cname + ".count", 1);
	if (count <= 0) {
	    count = 1;
	}
        append = manager.getBooleanProperty(cname + ".append", false);
	setLevel(manager.getLevelProperty(cname + ".level", Level.ALL));
	setFilter(manager.getFilterProperty(cname + ".filter", null));
	setFormatter(manager.getFormatterProperty(cname + ".formatter",	new XMLFormatter()));
	try {
	    setEncoding(manager.getStringProperty(cname +".encoding", null));
	} catch (Exception ex) {
	    try {
	        setEncoding(null);
	    } catch (Exception ex2) {
		// doing a setEncoding with null should always work.
		// assert false;
	    }
	}
    }


    /**
     * Construct a default <tt>FileHandler</tt>.  This will be configured
     * entirely from <tt>LogManager</tt> properties (or their default values).
     * <p>
     * @exception  IOException if there are IO problems opening the files.
     * @exception  SecurityException  if a security manager exists and if
     *             the caller does not have <tt>LoggingPermission("control"))</tt>.
     */
    public FileHandler() throws IOException, SecurityException {
	checkAccess();
	configure();
	openFiles();
    }

    /**
     * Initialize a <tt>FileHandler</tt> to write to the given filename.
     * <p>
     * The <tt>FileHandler</tt> is configured based on <tt>LogManager</tt>
     * properties (or their default values) except that the given pattern 
     * argument is used as the filename pattern, the file limit is
     * set to no limit, and the file count is set to one.
     * <p>
     * There is no limit on the amount of data that may be written,
     * so use this with care.
     *
     * @param pattern  the name of the output file
     * @exception  IOException if there are IO problems opening the files.
     * @exception  SecurityException  if a security manager exists and if
     *             the caller does not have <tt>LoggingPermission("control")</tt>.
     */
    public FileHandler(String pattern) throws IOException, SecurityException {
	checkAccess();
	configure();
	this.pattern = pattern;
	this.limit = 0;
	this.count = 1;
	openFiles();
    }

    /**
     * Initialize a <tt>FileHandler</tt> to write to the given filename,
     * with optional append.
     * <p>
     * The <tt>FileHandler</tt> is configured based on <tt>LogManager</tt>
     * properties (or their default values) except that the given pattern 
     * argument is used as the filename pattern, the file limit is
     * set to no limit, the file count is set to one, and the append
     * mode is set to the given <tt>append</tt> argument.
     * <p>
     * There is no limit on the amount of data that may be written,
     * so use this with care.
     *
     * @param pattern  the name of the output file
     * @param append  specifies append mode
     * @exception  IOException if there are IO problems opening the files.
     * @exception  SecurityException  if a security manager exists and if
     *             the caller does not have <tt>LoggingPermission("control")</tt>.
     */
    public FileHandler(String pattern, boolean append) throws IOException, SecurityException {
	checkAccess();
	configure();
	this.pattern = pattern;
	this.limit = 0;
	this.count = 1;
	this.append = append;
	openFiles();
    }

    /**
     * Initialize a <tt>FileHandler</tt> to write to a set of files.  When
     * (approximately) the given limit has been written to one file,
     * another file will be opened.  The output will cycle through a set
     * of count files.
     * <p>
     * The <tt>FileHandler</tt> is configured based on <tt>LogManager</tt>
     * properties (or their default values) except that the given pattern 
     * argument is used as the filename pattern, the file limit is
     * set to the limit argument, and the file count is set to the
     * given count argument.
     * <p>
     * The count must be at least 1.
     *
     * @param pattern  the pattern for naming the output file
     * @param limit  the maximum number of bytes to write to any one file
     * @param count  the number of files to use
     * @exception  IOException if there are IO problems opening the files.
     * @exception  SecurityException  if a security manager exists and if
     *             the caller does not have <tt>LoggingPermission("control")</tt>.
     * @exception IllegalArgumentException if limit < 0, or count < 1.
     */
    public FileHandler(String pattern, int limit, int count)
					throws IOException, SecurityException {
	if (limit < 0 || count < 1) {
	    throw new IllegalArgumentException();
	}
	checkAccess();
	configure();
	this.pattern = pattern;
	this.limit = limit;
	this.count = count;
	openFiles();
    }

    /**