java.util.logging
Class FileHandler

java.lang.Object
  java.util.logging.Handler
      java.util.logging.StreamHandler
          java.util.logging.FileHandler

public class FileHandler
extends StreamHandler

A Handler writes description of logging event into a specified file or a rotating set of files.

If a set of files are used, when a given amount of data has been written to one file, this file is closed, and another file is opened. The name of these files are generated by given name pattern, see below for details.

By default the IO buffering mechanism is enabled, but when each log record is complete, it is flushed out.

XMLFormatter is default formatter for FileHandler.

MemoryHandler will read following LogManager properties for initialization, if given properties are not defined or has invalid values, default value will be used.

• java.util.logging.FileHandler.level specifies the level for this Handler, defaults to Level.ALL.
• java.util.logging.FileHandler.filter specifies the Filter class name, defaults to no Filter.
• java.util.logging.FileHandler.formatter specifies the Formatter class, defaults to java.util.logging.XMLFormatter.
• java.util.logging.FileHandler.encoding specifies the character set encoding name, defaults to the default platform encoding.
• java.util.logging.FileHandler.limit specifies an maximum bytes to write to any one file, defaults to zero, which means no limit.
• java.util.logging.FileHandler.count specifies how many output files to rotate, defaults to 1.
• java.util.logging.FileHandler.pattern specifies name pattern for the output files. See below for details. Defaults to "%h/java%u.log".
• java.util.logging.FileHandler.append specifies whether this FileHandler should append onto existing files, defaults to false.

Name pattern is a string that may includes some special sub-strings, which will be replaced to generate output files:

• "/" represents the local pathname separator
• "%t" represents the system temporary directory
• "%h" represents the home directory of current user, which is specified by "user.home" system property
• "%g" represents the generation number to distinguish rotated logs
• "%u" represents a unique number to resolve conflicts
• "%%" represents percent sign character '%'

Normally, the generation numbers are not larger than given file count and follow the sequence 0, 1, 2.... If the file count is larger than one, but the generation field("%g") has not been specified in the pattern, then the generation number after a dot will be added to the end of the file name,

The "%u" unique field is used to avoid conflicts and set to 0 at first. If one FileHandler tries to open the filename which is currently in use by another process, it will repeatedly increment the unique number field and try again. If the "%u" component has not been included in the file name pattern and some contention on a file does occur then a unique numerical value will be added to the end of the filename in question immediately to the right of a dot. The unique IDs for avoiding conflicts is only guaranteed to work reliably when using a local disk file system.

Constructor Summary

FileHandler()
Construct a FileHandler using LogManager properties or their default value

FileHandler(String pattern)
Construct a FileHandler, the given name pattern is used as output filename, the file limit is set to zero(no limit), and the file count is set to one, other configuration using LogManager properties or their default value This handler write to only one file and no amount limit.

FileHandler(String pattern, boolean append)
Construct a FileHandler, the given name pattern is used as output filename, the file limit is set to zero(i.e. no limit applies), the file count is initialized to one, and the value of append becomes the new instance's append mode.

FileHandler(String pattern, int limit, int count)
Construct a FileHandler, the given name pattern is used as output filename, the file limit is set to given limit argument, and the file count is set to given count argument, other configuration using LogManager properties or their default value This handler is configured to write to a rotating set of count files, when the limit of bytes has been written to one output file, another file will be opened instead.

FileHandler(String pattern, int limit, int count, boolean append)
Construct a FileHandler, the given name pattern is used as output filename, the file limit is set to given limit argument, the file count is set to given count argument, and the append mode is set to given append argument, other configuration using LogManager properties or their default value This handler is configured to write to a rotating set of count files, when the limit of bytes has been written to one output file, another file will be opened instead.

Method Summary

void	close() Flush and close all opened files.
void	publish(LogRecord record) Publish a LogRecord

Methods inherited from class java.util.logging.StreamHandler

flush, isLoggable, setEncoding, setOutputStream

Methods inherited from class java.util.logging.Handler

getEncoding, getErrorManager, getFilter, getFormatter, getLevel, reportError, setErrorManager, setFilter, setFormatter, setLevel

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FileHandler

public FileHandler()
            throws IOException

Construct a FileHandler using LogManager properties or their default value

Throws:

IOException - if any IO exception happened

SecurityException - if security manager exists and it determines that caller does not have the required permissions to control this handler, required permissions include LogPermission("control") and other permission like FilePermission("write"), etc.

FileHandler

public FileHandler(String pattern)
            throws IOException

Construct a FileHandler, the given name pattern is used as output filename, the file limit is set to zero(no limit), and the file count is set to one, other configuration using LogManager properties or their default value This handler write to only one file and no amount limit.

Parameters:

pattern - the name pattern of output file

Throws:

IOException - if any IO exception happened

SecurityException - if security manager exists and it determines that caller does not have the required permissions to control this handler, required permissions include LogPermission("control") and other permission like FilePermission("write"), etc.

FileHandler

public FileHandler(String pattern,
                   boolean append)
            throws IOException

Construct a FileHandler, the given name pattern is used as output filename, the file limit is set to zero(i.e. no limit applies), the file count is initialized to one, and the value of append becomes the new instance's append mode. Other configuration is done using LogManager properties. This handler write to only one file and no amount limit.

Parameters:

pattern - the name pattern of output file

append - the append mode

Throws:

IOException - if any IO exception happened

SecurityException - if security manager exists and it determines that caller does not have the required permissions to control this handler, required permissions include LogPermission("control") and other permission like FilePermission("write"), etc.

FileHandler

public FileHandler(String pattern,
                   int limit,
                   int count)
            throws IOException

Construct a FileHandler, the given name pattern is used as output filename, the file limit is set to given limit argument, and the file count is set to given count argument, other configuration using LogManager properties or their default value This handler is configured to write to a rotating set of count files, when the limit of bytes has been written to one output file, another file will be opened instead.

Parameters:

pattern - the name pattern of output file

limit - the data amount limit in bytes of one output file, cannot less than one

count - the maximum number of files can be used, cannot less than one

Throws:

IOException - if any IO exception happened

SecurityException - if security manager exists and it determines that caller does not have the required permissions to control this handler, required permissions include LogPermission("control") and other permission like FilePermission("write"), etc.

IllegalArgumentException - if count<1, or limit<0

FileHandler

public FileHandler(String pattern,
                   int limit,
                   int count,
                   boolean append)
            throws IOException

Construct a FileHandler, the given name pattern is used as output filename, the file limit is set to given limit argument, the file count is set to given count argument, and the append mode is set to given append argument, other configuration using LogManager properties or their default value This handler is configured to write to a rotating set of count files, when the limit of bytes has been written to one output file, another file will be opened instead.

Parameters:

pattern - the name pattern of output file

limit - the data amount limit in bytes of one output file, cannot less than one

count - the maximum number of files can be used, cannot less than one

append - the append mode

Throws:

IOException - if any IO exception happened

SecurityException - if security manager exists and it determines that caller does not have the required permissions to control this handler, required permissions include LogPermission("control") and other permission like FilePermission("write"), etc.

IllegalArgumentException - if count<1, or limit<0

Method Detail

close

public void close()

Flush and close all opened files.

Overrides:

close in class StreamHandler

Throws:

SecurityException - if security manager exists and it determines that caller does not have the required permissions to control this handler, required permissions include LogPermission("control") and other permission like FilePermission("write"), etc.

publish

public void publish(LogRecord record)

Publish a LogRecord

Overrides:

publish in class StreamHandler

Parameters:

record - the log record to be published