Java tutorial
/* * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.util.logging; import java.io.*; import java.net.*; /** * Simple network logging {@code Handler}. * <p> * {@code LogRecords} are published to a network stream connection. By default * the {@code XMLFormatter} class is used for formatting. * <p> * <b>Configuration:</b> * By default each {@code SocketHandler} is initialized using the following * {@code LogManager} configuration properties where {@code <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. * <ul> * <li> <handler-name>.level * specifies the default level for the {@code Handler} * (defaults to {@code Level.ALL}). </li> * <li> <handler-name>.filter * specifies the name of a {@code Filter} class to use * (defaults to no {@code Filter}). </li> * <li> <handler-name>.formatter * specifies the name of a {@code Formatter} class to use * (defaults to {@code java.util.logging.XMLFormatter}). </li> * <li> <handler-name>.encoding * the name of the character set encoding to use (defaults to * the default platform encoding). </li> * <li> <handler-name>.host * specifies the target host name to connect to (no default). </li> * <li> <handler-name>.port * specifies the target TCP port to use (no default). </li> * </ul> * <p> * For example, the properties for {@code SocketHandler} would be: * <ul> * <li> java.util.logging.SocketHandler.level=INFO </li> * <li> java.util.logging.SocketHandler.formatter=java.util.logging.SimpleFormatter </li> * </ul> * <p> * For a custom handler, e.g. com.foo.MyHandler, the properties would be: * <ul> * <li> com.foo.MyHandler.level=INFO </li> * <li> com.foo.MyHandler.formatter=java.util.logging.SimpleFormatter </li> * </ul> * <p> * The output IO stream is buffered, but is flushed after each * {@code LogRecord} is written. * * @since 1.4 */ public class SocketHandler extends StreamHandler { private Socket sock; private String host; private int port; /** * Create a {@code SocketHandler}, using only {@code LogManager} properties * (or their defaults). * @throws IllegalArgumentException if the host or port are invalid or * are not specified as LogManager properties. * @throws IOException if we are unable to connect to the target * host and port. */ public SocketHandler() throws IOException { // configure with specific defaults for SocketHandler super(Level.ALL, new XMLFormatter(), null); LogManager manager = LogManager.getLogManager(); String cname = getClass().getName(); port = manager.getIntProperty(cname + ".port", 0); host = manager.getStringProperty(cname + ".host", null); try { connect(); } catch (IOException ix) { System.err.println("SocketHandler: connect failed to " + host + ":" + port); throw ix; } } /** * Construct a {@code SocketHandler} using a specified host and port. * * The {@code SocketHandler} is configured based on {@code LogManager} * properties (or their default values) except that the given target host * and port arguments are used. If the host argument is empty, but not * null String then the localhost is used. * * @param host target host. * @param port target port. * * @throws IllegalArgumentException if the host or port are invalid. * @throws IOException if we are unable to connect to the target * host and port. */ public SocketHandler(String host, int port) throws IOException { // configure with specific defaults for SocketHandler super(Level.ALL, new XMLFormatter(), null); this.port = port; this.host = host; connect(); } private void connect() throws IOException { // Check the arguments are valid. if (port == 0) { throw new IllegalArgumentException("Bad port: " + port); } if (host == null) { throw new IllegalArgumentException("Null host name: " + host); } // Try to open a new socket. sock = new Socket(host, port); OutputStream out = sock.getOutputStream(); BufferedOutputStream bout = new BufferedOutputStream(out); setOutputStreamPrivileged(bout); } /** * Close this output stream. * * @exception SecurityException if a security manager exists and if * the caller does not have {@code LoggingPermission("control")}. */ @Override public synchronized void close() throws SecurityException { super.close(); if (sock != null) { try { sock.close(); } catch (IOException ix) { // drop through. } } sock = null; } /** * Format and publish a {@code LogRecord}. * * @param record description of the log event. A null record is * silently ignored and is not published */ @Override public synchronized void publish(LogRecord record) { if (!isLoggable(record)) { return; } super.publish(record); flush(); } }