Module java.logging
Package java.util.logging

Class StreamHandler

java.lang.Object
java.util.logging.Handler
java.util.logging.StreamHandler
Direct Known Subclasses:
ConsoleHandler, FileHandler, SocketHandler
public class StreamHandler extends Handler
Stream based logging Handler.

This is primarily intended as a base class or support class to be used in implementing other logging Handlers.

LogRecords are published to a given java.io.OutputStream.

Configuration: By default each StreamHandler 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 to Level.INFO).
  • <handler-name>.filter specifies the name of a Filter class to use (defaults to no Filter).
  • <handler-name>.formatter specifies the name of a Formatter class to use (defaults to java.util.logging.SimpleFormatter).
  • <handler-name>.encoding the name of the character set encoding to use (defaults to the default platform encoding).

For example, the properties for StreamHandler would be:

  • java.util.logging.StreamHandler.level=INFO
  • java.util.logging.StreamHandler.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
Since:
1.4

  • Constructor Details

    • StreamHandler

      public StreamHandler()
      Create a StreamHandler, with no current output stream.

    • StreamHandler

      public StreamHandler​(OutputStream out, Formatter formatter)
      Create a StreamHandler with a given Formatter and output stream.
      Parameters:
      out - the target output stream
      formatter - Formatter to be used to format output

  • Method Details

    • setOutputStream

      protected void setOutputStream​(OutputStream out) throws SecurityException
      Change the output stream.

      If there is a current output stream then the Formatter's tail string is written and the stream is flushed and closed. Then the output stream is replaced with the new output stream.

      Parameters:
      out - New output stream. May not be null.
      Throws:
      SecurityException - if a security manager exists and if the caller does not have LoggingPermission("control").

    • setEncoding

      public void setEncoding​(String encoding) throws SecurityException, UnsupportedEncodingException
      Set (or change) the character encoding used by this Handler.

      The encoding should be set before any LogRecords are written to the Handler.

      Overrides:
      setEncoding in class Handler
      Parameters:
      encoding - The name of a supported character encoding. May be null, to indicate the default platform encoding.
      Throws:
      SecurityException - if a security manager exists and if the caller does not have LoggingPermission("control").
      UnsupportedEncodingException - if the named encoding is not supported.

    • publish

      public void publish​(LogRecord record)
      Format and publish a LogRecord.

      The StreamHandler first checks if there is an OutputStream and if the given LogRecord has at least the required log level. If not it silently returns. If so, it calls any associated Filter to check if the record should be published. If so, it calls its Formatter to format the record and then writes the result to the current output stream.

      If this is the first LogRecord to be written to a given OutputStream, the Formatter's "head" string is written to the stream before the LogRecord is written.

      Specified by:
      publish in class Handler
      Parameters:
      record - description of the log event. A null record is silently ignored and is not published

    • isLoggable

      public boolean isLoggable​(LogRecord record)
      Check if this Handler would actually log a given LogRecord.

      This method checks if the LogRecord has an appropriate level and whether it satisfies any Filter. It will also return false if no output stream has been assigned yet or the LogRecord is null.

      Overrides:
      isLoggable in class Handler
      Parameters:
      record - a LogRecord (may be null).
      Returns:
      true if the LogRecord would be logged.

    • flush

      public void flush()
      Flush any buffered messages.
      Specified by:
      flush in class Handler

    • close

      public void close() throws SecurityException
      Close the current output stream.

      The Formatter's "tail" string is written to the stream before it is closed. In addition, if the Formatter's "head" string has not yet been written to the stream, it will be written before the "tail" string.

      Specified by:
      close in class Handler
      Throws:
      SecurityException - if a security manager exists and if the caller does not have LoggingPermission("control").