Class FileHandler
- java.lang.Object
-
- java.util.logging.Handler
-
- java.util.logging.StreamHandler
-
- java.util.logging.FileHandler
public class FileHandler extends StreamHandler
Simple file logging Handler
.
The FileHandler
can either write to a specified file, or it can write to a rotating set of files.
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.
By default buffering is enabled in the IO libraries but each log record is flushed out when it is complete.
By default the XMLFormatter
class is used for formatting.
Configuration: By default each FileHandler
is initialized using the following LogManager
configuration properties where <handler-name>
refers to the fully-qualified class name of the handler. If properties are not defined (or have invalid values) then the specified default values are used.
- <handler-name>.level specifies the default level for the
Handler
(defaults toLevel.ALL
). - <handler-name>.filter specifies the name of a
Filter
class to use (defaults to noFilter
). - <handler-name>.formatter specifies the name of a
Formatter
class to use (defaults tojava.util.logging.XMLFormatter
) - <handler-name>.encoding the name of the character set encoding to use (defaults to the default platform encoding).
- <handler-name>.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).
- <handler-name>.count specifies how many output files to cycle through (defaults to 1).
- <handler-name>.pattern specifies a pattern for generating the output file name. See below for details. (Defaults to "%h/java%u.log").
- <handler-name>.append specifies whether the FileHandler should append onto any existing files (defaults to false).
- <handler-name>.maxLocks specifies the maximum number of concurrent locks held by FileHandler (defaults to 100).
For example, the properties for FileHandler
would be:
- java.util.logging.FileHandler.level=INFO
- java.util.logging.FileHandler.formatter=java.util.logging.SimpleFormatter
For a custom handler, e.g. com.foo.MyHandler, the properties would be:
- com.foo.MyHandler.level=INFO
- com.foo.MyHandler.formatter=java.util.logging.SimpleFormatter
A pattern consists of a string that includes the following special components that will be replaced at runtime:
- "/" the local pathname separator
- "%t" the system temporary directory
- "%h" the value of the "user.home" system property
- "%g" the generation number to distinguish rotated logs
- "%u" a unique number to resolve conflicts
- "%%" translates to a single percent sign "%"
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 C:\TEMP\java0.log and C:\TEMP\java1.log
Generation numbers follow the sequence 0, 1, 2, etc.
Normally the "%u" unique field is set to 0. However, if the FileHandler
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 FileHandler
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.)
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.
Note that the use of unique ids to avoid conflicts is only guaranteed to work reliably when using a local disk file system.
- Since:
- 1.4
Constructor Summary
Constructor | Description |
---|---|
FileHandler() | Construct a default |
FileHandler(String pattern) | Initialize a |
FileHandler(String pattern,
boolean append) | Initialize a |
FileHandler(String pattern,
int limit,
int count) | Initialize a |
FileHandler(String pattern,
int limit,
int count,
boolean append) | Initialize a |
FileHandler(String pattern,
long limit,
int count,
boolean append) | Initialize a |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
void | close() | Close all the files. |
void | publish(LogRecord record) | Format and publish a |
Methods declared in class java.util.logging.StreamHandler
flush, isLoggable, setEncoding, setOutputStream
Methods declared in class java.util.logging.Handler
getEncoding, getErrorManager, getFilter, getFormatter, getLevel, reportError, setErrorManager, setFilter, setFormatter, setLevel
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Constructor Detail
FileHandler
public FileHandler() throws IOException, SecurityException
Construct a default FileHandler
. This will be configured entirely from LogManager
properties (or their default values).
- Throws:
-
IOException
- if there are IO problems opening the files. -
SecurityException
- if a security manager exists and if the caller does not haveLoggingPermission("control"))
. -
NullPointerException
- if pattern property is an empty String.
FileHandler
public FileHandler(String pattern) throws IOException, SecurityException
Initialize a FileHandler
to write to the given filename.
The FileHandler
is configured based on LogManager
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.
There is no limit on the amount of data that may be written, so use this with care.
- Parameters:
-
pattern
- the name of the output file - Throws:
-
IOException
- if there are IO problems opening the files. -
SecurityException
- if a security manager exists and if the caller does not haveLoggingPermission("control")
. -
IllegalArgumentException
- if pattern is an empty string
FileHandler
public FileHandler(String pattern, boolean append) throws IOException, SecurityException
Initialize a FileHandler
to write to the given filename, with optional append.
The FileHandler
is configured based on LogManager
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 append
argument.
There is no limit on the amount of data that may be written, so use this with care.
- Parameters:
-
pattern
- the name of the output file -
append
- specifies append mode - Throws:
-
IOException
- if there are IO problems opening the files. -
SecurityException
- if a security manager exists and if the caller does not haveLoggingPermission("control")
. -
IllegalArgumentException
- if pattern is an empty string
FileHandler
public FileHandler(String pattern, int limit, int count) throws IOException, SecurityException
Initialize a FileHandler
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.
The FileHandler
is configured based on LogManager
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.
The count must be at least 1.
- Parameters:
-
pattern
- the pattern for naming the output file -
limit
- the maximum number of bytes to write to any one file -
count
- the number of files to use - Throws:
-
IOException
- if there are IO problems opening the files. -
SecurityException
- if a security manager exists and if the caller does not haveLoggingPermission("control")
. -
IllegalArgumentException
- iflimit < 0
, orcount < 1
. -
IllegalArgumentException
- if pattern is an empty string
FileHandler
public FileHandler(String pattern, int limit, int count, boolean append) throws IOException, SecurityException
Initialize a FileHandler
to write to a set of files with optional append. 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.
The FileHandler
is configured based on LogManager
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, and the append mode is set to the given append
argument.
The count must be at least 1.
- Parameters:
-
pattern
- the pattern for naming the output file -
limit
- the maximum number of bytes to write to any one file -
count
- the number of files to use -
append
- specifies append mode - Throws:
-
IOException
- if there are IO problems opening the files. -
SecurityException
- if a security manager exists and if the caller does not haveLoggingPermission("control")
. -
IllegalArgumentException
- iflimit < 0
, orcount < 1
. -
IllegalArgumentException
- if pattern is an empty string
FileHandler
public FileHandler(String pattern, long limit, int count, boolean append) throws IOException
Initialize a FileHandler
to write to a set of files with optional append. 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.
The FileHandler
is configured based on LogManager
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, and the append mode is set to the given append
argument.
The count must be at least 1.
- Parameters:
-
pattern
- the pattern for naming the output file -
limit
- the maximum number of bytes to write to any one file -
count
- the number of files to use -
append
- specifies append mode - Throws:
-
IOException
- if there are IO problems opening the files. -
SecurityException
- if a security manager exists and if the caller does not haveLoggingPermission("control")
. -
IllegalArgumentException
- iflimit < 0
, orcount < 1
. -
IllegalArgumentException
- if pattern is an empty string - Since:
- 9
Method Detail
publish
public void publish(LogRecord record)
Format and publish a LogRecord
.
- Overrides:
-
publish
in classStreamHandler
- Parameters:
-
record
- description of the log event. A null record is silently ignored and is not published
close
public void close() throws SecurityException
Close all the files.
- Overrides:
-
close
in classStreamHandler
- Throws:
-
SecurityException
- if a security manager exists and if the caller does not haveLoggingPermission("control")
.