| FileHandler | java.util.logging |
This Handler subclass formats LogRecord objects and outputs the resulting strings to a file or to a rotating set of files. Arguments passed to the FileHandler( ) constructor specify which file or files are used, and how they are used. The arguments are optional, and if they are not specified, defaults are obtained through LogManager.getProperty( ) as described below. The constructor arguments are: -
- pattern
-
A string containing substitution characters that describes one or more files to use. The substitutions performed to convert this pattern to a filename are described below. -
- limit
-
An approximate maximum file size for the log file, or 0 for no limit. If count is set to greater than one, then when a log file reaches this maximum, FileHandler closes it, renames it, and then starts a new log with the original filename. -
- count
-
When limit is set to be nonzero, this arguemnt specifies the number of old log files to retain. -
- append
-
TRue if the FileHandler should append to log messages already in the named file, or false if it should overwrite the file. The pattern argument is the most important of these: it specifies which file or files the FileHandler will write to. FileHandler performs the following substitutions on the specified pattern to convert it to a filename: | For | Substitute | | / | The directory separator character for the platform. This means that you can always use a forward slash in your patterns, even on Windows filesystems that use backward slashes . | | %% | A single literal percent sign. | | %h | The user's home directory: the value of the system property " user .home". | | %t | The temporary directory for the system. | | %u | A unique number to be used to distinguish this log file from other log files with the same pattern (this may be necessary when multiple Java programs are creating logs at the same time). | | %g | The "generation number" of old log files when the limit argument is nonzero and the count argument is greater than one. FileHandler always writes log records into a file in which %g is replaced by 0. But when that file fills up, it is closed and renamed with the 0 replaced by a 1. Older files are similarly renamed , with their generation number being incremented. When the number of log files reaches the number specifed by count , then the oldest file is deleted to make room for the new one. |
When a FileHandler is created, the LogManager.getProperty( ) method is used to obtain defaults for any unspecified constructor arguments, and also to obtian initial values for the various properties inherited from Handler . The table below lists these arguments and properties, the value passed to getProperty( ) , and the default value used if getProperty( ) returns null . See Handler for further details. | Property or argument | LogManager property name | Default | | level | java.util.logging.FileHandler.level | Level.ALL | | filter | java.util.logging.FileHandler.filter | null | | formatter | java.util.logging.FileHandler.formatter | XMLFormatter | | encoding | java.util.logging.FileHandler.encoding | platform default | | pattern | java.util.logging.FileHandler.pattern | %h/java%u.log | | limit | java.util.logging.FileHandler.limit | 0 (no limit) | | count | java.util.logging.FileHandler.count | 1 | | append | java.util.logging.FileHandler.append | false |
Figure 16-115. java.util.logging.FileHandler 
public class FileHandler extends StreamHandler { // Public Constructors public FileHandler ( ) throws java.io.IOException, SecurityException; public FileHandler (String pattern ) throws java.io.IOException, SecurityException; public FileHandler (String pattern , boolean append ) throws java.io.IOException, SecurityException; public FileHandler (String pattern , int limit , int count ) throws java.io.IOException, SecurityException; public FileHandler (String pattern , int limit , int count , boolean append ) throws java.io.IOException, SecurityException; // Public Methods Overriding StreamHandler public void close ( ) throws SecurityException; synchronized public void publish (LogRecord record ); synchronized }
|
