Log4J:Hvordan omdirigerer jeg en OutputStream eller Writer til loggerens forfatter(e)?
Mit forslag er, hvorfor skriver du så ikke din OutputStream?! Jeg var ved at skrive et til dig, men jeg fandt dette gode eksempel på nettet, tjek det ud!
LogOutputStream.java
/*
* Jacareto Copyright (c) 2002-2005
* Applied Computer Science Research Group, Darmstadt University of
* Technology, Institute of Mathematics & Computer Science,
* Ludwigsburg University of Education, and Computer Based
* Learning Research Group, Aachen University. All rights reserved.
*
* Jacareto is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* Jacareto 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 for more details.
*
* You should have received a copy of the GNU General Public
* License along with Jacareto; if not, write to the Free
* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
package jacareto.toolkit.log4j;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;
import java.io.OutputStream;
/**
* This class logs all bytes written to it as output stream with a specified logging level.
*
* @author <a href="mailto:[email protected]">Christian Spannagel</a>
* @version 1.0
*/
public class LogOutputStream extends OutputStream {
/** The logger where to log the written bytes. */
private Logger logger;
/** The level. */
private Level level;
/** The internal memory for the written bytes. */
private String mem;
/**
* Creates a new log output stream which logs bytes to the specified logger with the specified
* level.
*
* @param logger the logger where to log the written bytes
* @param level the level
*/
public LogOutputStream (Logger logger, Level level) {
setLogger (logger);
setLevel (level);
mem = "";
}
/**
* Sets the logger where to log the bytes.
*
* @param logger the logger
*/
public void setLogger (Logger logger) {
this.logger = logger;
}
/**
* Returns the logger.
*
* @return DOCUMENT ME!
*/
public Logger getLogger () {
return logger;
}
/**
* Sets the logging level.
*
* @param level DOCUMENT ME!
*/
public void setLevel (Level level) {
this.level = level;
}
/**
* Returns the logging level.
*
* @return DOCUMENT ME!
*/
public Level getLevel () {
return level;
}
/**
* Writes a byte to the output stream. This method flushes automatically at the end of a line.
*
* @param b DOCUMENT ME!
*/
public void write (int b) {
byte[] bytes = new byte[1];
bytes[0] = (byte) (b & 0xff);
mem = mem + new String(bytes);
if (mem.endsWith ("\n")) {
mem = mem.substring (0, mem.length () - 1);
flush ();
}
}
/**
* Flushes the output stream.
*/
public void flush () {
logger.log (level, mem);
mem = "";
}
}
Du kan bruge Log4j IOStreams
IOStreams-komponenten er en Log4j API-udvidelse, der giver adskillige klasser fra java.io, der enten kan skrive til en Logger, mens du skriver til en anden OutputStream eller Writer, eller indholdet, der læses af en InputStream eller Reader, kan aflyttes af en Logger.
Du kan oprette en OutputStream på denne måde:
OutputStream outputStream = IoBuilder
.forLogger(logger)
.buildOutputStream();
Nedenfor er et eksempel med Appium, der starter det programmatisk og styrer dets log med log4j.
final Logger logger = LogManager.getLogger(getClass());
cap = new DesiredCapabilities();
cap.setCapability("noReset", "false");
//Build the Appium service
builder = new AppiumServiceBuilder();
builder.withIPAddress("127.0.0.1");
builder.usingPort(4723);
builder.withCapabilities(cap);
builder.withArgument(GeneralServerFlag.SESSION_OVERRIDE);
builder.withArgument(GeneralServerFlag.LOG_LEVEL,"debug");
//Start the server with the builder
service = AppiumDriverLocalService.buildService(builder);
OutputStream outputStream = IoBuilder
.forLogger(logger)
.buildOutputStream();
service.addOutPutStream(outputStream);
service.start();
Håber dette hjælper!!!
Kilde:http://sysgears.com/articles/how-to-redirect-stdout-and-stderr-writing-to-a-log4j-appender/
Blokcitat
Log4j tillader ikke at fange stdout- og stderr-meddelelser ud af boksen. Men hvis du bruger tredjepartskomponenter og skal logge beskeder om, at de flyder til strømmene, så kan du lave et lille trick og implementere tilpasset outputstrøm, der understøtter logning.
Dette er allerede blevet gjort af Jim Moore (se LoggingOutputStream i log4j-kildekoden). Det eneste problem er, at JimMoores LoggingOutputStream kræver org.apache.log4j.Category og org.apache.log4j.Priority, som nu er delvist forældet.
Her er modificeret LoggingOutputStream, der undgår forældede metoder:
public class LoggingOutputStream extends OutputStream {
/**
* Default number of bytes in the buffer.
*/
private static final int DEFAULT_BUFFER_LENGTH = 2048;
/**
* Indicates stream state.
*/
private boolean hasBeenClosed = false;
/**
* Internal buffer where data is stored.
*/
private byte[] buf;
/**
* The number of valid bytes in the buffer.
*/
private int count;
/**
* Remembers the size of the buffer.
*/
private int curBufLength;
/**
* The logger to write to.
*/
private Logger log;
/**
* The log level.
*/
private Level level;
/**
* Creates the Logging instance to flush to the given logger.
*
* @param log the Logger to write to
* @param level the log level
* @throws IllegalArgumentException in case if one of arguments
* is null.
*/
public LoggingOutputStream(final Logger log,
final Level level)
throws IllegalArgumentException {
if (log == null || level == null) {
throw new IllegalArgumentException(
"Logger or log level must be not null");
}
this.log = log;
this.level = level;
curBufLength = DEFAULT_BUFFER_LENGTH;
buf = new byte[curBufLength];
count = 0;
}
/**
* Writes the specified byte to this output stream.
*
* @param b the byte to write
* @throws IOException if an I/O error occurs.
*/
public void write(final int b) throws IOException {
if (hasBeenClosed) {
throw new IOException("The stream has been closed.");
}
// don't log nulls
if (b == 0) {
return;
}
// would this be writing past the buffer?
if (count == curBufLength) {
// grow the buffer
final int newBufLength = curBufLength +
DEFAULT_BUFFER_LENGTH;
final byte[] newBuf = new byte[newBufLength];
System.arraycopy(buf, 0, newBuf, 0, curBufLength);
buf = newBuf;
curBufLength = newBufLength;
}
buf[count] = (byte) b;
count++;
}
/**
* Flushes this output stream and forces any buffered output
* bytes to be written out.
*/
public void flush() {
if (count == 0) {
return;
}
final byte[] bytes = new byte[count];
System.arraycopy(buf, 0, bytes, 0, count);
String str = new String(bytes);
log.log(level, str);
count = 0;
}
/**
* Closes this output stream and releases any system resources
* associated with this stream.
*/
public void close() {
flush();
hasBeenClosed = true;
}
}
Nu kan du fange beskeder, der skylles til stderr eller stdout på følgende måde:
System.setErr(new PrintStream(new LoggingOutputStream(
Logger.getLogger("outLog"), Level.ERROR)));
log4j.properties-konfigurationen:
log4j.logger.outLog=error, out_log
log4j.appender.out_log=org.apache.log4j.RollingFileAppender
log4j.appender.out_log.file=/logs/error.log
log4j.appender.out_log.MaxFileSize=10MB
log4j.appender.out_log.threshold=error
Dmitriy Pavlenko, SysGears
Blokcitat
