org.apache.log4j.net.TelnetAppender Maven / Gradle / Ivy
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.log4j.net;
import org.apache.log4j.AppenderSkeleton;
import org.apache.log4j.helpers.LogLog;
import org.apache.log4j.spi.LoggingEvent;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.InterruptedIOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Vector;
/**
The TelnetAppender is a log4j appender that specializes in
writing to a read-only socket. The output is provided in a
telnet-friendly way so that a log can be monitored over TCP/IP.
Clients using telnet connect to the socket and receive log data.
This is handy for remote monitoring, especially when monitoring a
servlet.
Here is a list of the available configuration options:
Name
Requirement
Description
Sample Value
Port
optional
This parameter determines the port to use for announcing log events. The default port is 23 (telnet).
5875
@author Jay Funnell
*/
public class TelnetAppender extends AppenderSkeleton {
private SocketHandler sh;
private int port = 23;
/**
This appender requires a layout to format the text to the
attached client(s). */
public boolean requiresLayout() {
return true;
}
/** all of the options have been set, create the socket handler and
wait for connections. */
public void activateOptions() {
try {
sh = new SocketHandler(port);
sh.start();
}
catch(InterruptedIOException e) {
Thread.currentThread().interrupt();
e.printStackTrace();
} catch(IOException e) {
e.printStackTrace();
} catch(RuntimeException e) {
e.printStackTrace();
}
super.activateOptions();
}
public
int getPort() {
return port;
}
public
void setPort(int port) {
this.port = port;
}
/** shuts down the appender. */
public void close() {
if (sh != null) {
sh.close();
try {
sh.join();
} catch(InterruptedException ex) {
Thread.currentThread().interrupt();
}
}
}
/** Handles a log event. For this appender, that means writing the
message to each connected client. */
protected void append(LoggingEvent event) {
if(sh != null) {
sh.send(layout.format(event));
if(layout.ignoresThrowable()) {
String[] s = event.getThrowableStrRep();
if (s != null) {
StringBuffer buf = new StringBuffer();
for(int i = 0; i < s.length; i++) {
buf.append(s[i]);
buf.append("\r\n");
}
sh.send(buf.toString());
}
}
}
}
//---------------------------------------------------------- SocketHandler:
/** The SocketHandler class is used to accept connections from
clients. It is threaded so that clients can connect/disconnect
asynchronously. */
protected class SocketHandler extends Thread {
private Vector writers = new Vector();
private Vector connections = new Vector();
private ServerSocket serverSocket;
private int MAX_CONNECTIONS = 20;
public void finalize() {
close();
}
/**
* make sure we close all network connections when this handler is destroyed.
* @since 1.2.15
*/
public void close() {
synchronized(this) {
for(Enumeration e = connections.elements();e.hasMoreElements();) {
try {
((Socket)e.nextElement()).close();
} catch(InterruptedIOException ex) {
Thread.currentThread().interrupt();
} catch(IOException ex) {
} catch(RuntimeException ex) {
}
}
}
try {
serverSocket.close();
} catch(InterruptedIOException ex) {
Thread.currentThread().interrupt();
} catch(IOException ex) {
} catch(RuntimeException ex) {
}
}
/** sends a message to each of the clients in telnet-friendly output. */
public synchronized void send(final String message) {
Iterator ce = connections.iterator();
for(Iterator e = writers.iterator();e.hasNext();) {
ce.next();
PrintWriter writer = (PrintWriter)e.next();
writer.print(message);
if(writer.checkError()) {
ce.remove();
e.remove();
}
}
}
/**
Continually accepts client connections. Client connections
are refused when MAX_CONNECTIONS is reached.
*/
public void run() {
while(!serverSocket.isClosed()) {
try {
Socket newClient = serverSocket.accept();
PrintWriter pw = new PrintWriter(newClient.getOutputStream());
if(connections.size() < MAX_CONNECTIONS) {
synchronized(this) {
connections.addElement(newClient);
writers.addElement(pw);
pw.print("TelnetAppender v1.0 (" + connections.size()
+ " active connections)\r\n\r\n");
pw.flush();
}
} else {
pw.print("Too many connections.\r\n");
pw.flush();
newClient.close();
}
} catch(Exception e) {
if (e instanceof InterruptedIOException || e instanceof InterruptedException) {
Thread.currentThread().interrupt();
}
if (!serverSocket.isClosed()) {
LogLog.error("Encountered error while in SocketHandler loop.", e);
}
break;
}
}
try {
serverSocket.close();
} catch(InterruptedIOException ex) {
Thread.currentThread().interrupt();
} catch(IOException ex) {
}
}
public SocketHandler(int port) throws IOException {
serverSocket = new ServerSocket(port);
setName("TelnetAppender-" + getName() + "-" + port);
}
}
}