I'm making a project backup java application, that needs to create a mail report and send it every day. My idea was to generate the body message, and to attach to the email the application log.
I'm using slf4j logger, and I don't know ho to automatically retrieve the log file path using the logger.
Using plain log4j seems to be easy, but I can't get out trying to retrieve it from the slf4j logger. Anyone faced this problem?
At the end this is what I did, and it seems to work fine.
Any review or comment will be appreciated!
private File getLogFile(){
File file = null;
Appender rightAppender = null;
Enumeration<Appender> e = org.apache.log4j.Logger.getRootLogger().getAllAppenders();
while(e.hasMoreElements()){
Appender appender = (Appender)e.nextElement();
if(appender instanceof FileAppender){
rightAppender = appender;
}
}
if(null != rightAppender){
file = new File(((FileAppender)rightAppender).getFile());
}
return file;
}
There is no such thing as an SLF4J logger. SLF4J is a facade for another logging framework (log4j, commons-logging, java.util.Log, etc.). So an SLF4J logger is always just a wrapper around a logger in one of the supported frameworks. Look at how you configured the logger underneath.
So in your case, if you are using slf4j with log4j, consult your log4j.properties or log4j.xml as usual to find where your logs are. And if you haven't set up either of those files (or otherwise initialized log4j), you don't have logs.
Related
I need generate one log file by each application installed and running on websphere application server 9.
I use JUL for generate log's file. My solution was create a especific Class thas inherits from FileHandler and set logs properties by a config file.
This is my code:
//Read config file
LogManager.getLogManager().readConfiguration(LoggerJUL.class.getResourceAsStream("/Logger.properties"));
//Add handler to logger
Logger.getLogger(clazz)).addHandler(new PersonalFileHandler());
PersonalFileHandler extends FileHandler, and properties are set by configure method on FileHandler class on runtime.
In this way i achieve make one log file by application running over Websphere, without overwriting the destination of the server log.
Although I achieve part of the objective, extra files are generated if the original log file is locked, same like this: testLogs.log.0, testLogs.log.1, testLogs.log.0.1, etc.
I read many suggestions and solutions, but i can't stop this isue.
Any suggestions ?
handlers = com.mucam.xxxx.PersonalFileHandler
# Set the default formatter to be the simple formatter
com.mucam.xxxx.PersonalFileHandler.formatter = java.util.logging.SimpleFormatter
# Write the log files to some file pattern
com.mucam.xxxx.PersonalFileHandler.pattern = C:/Users/pmendez/Documents/Log/testLogs.log
# Limit log file size to 5 Kb
com.mucam.xxxx.PersonalFileHandler.limit = 5000
# Keep 10 log files
com.mucam.xxxx.PersonalFileHandler.count = 10
#Customize the SimpleFormatter output format
java.util.logging.SimpleFormatter.format = %d{ISO8601} [%t] %-5p %c %x - %m%n
#Append to existing file
com.mucam.xxxx.PersonalFileHandler.append = true
Although I achieve part of the objective, extra files are generated if the original log file is locked, same like this: testLogs.log.0, testLogs.log.1, testLogs.log.0.1, etc. I read many suggestions and solutions, but i can't stop this isue. Any suggestions ?
Since your count is set to 10 you need to specify the %g pattern to log the generation.
com.mucam.xxxx.PersonalFileHandler.pattern = C:/Users/pmendez/Documents/Log/testLogs%g.log
The pattern is absolute path so if you create multiple filehandlers it will resolve conflicts by appending unique number to the end. This is specified by the %u pattern. So if you want to move where the integer is placed in the file name you specify the %u token in the pattern.
This also means that you are creating multiple instances of your custom file handler and they are not being closed. If you want to control the number of files you either need to control the number of PersonalFileHandler you create and or share a reference to singleton PersonalFileHandler. Otherwise you need to make sure that if you explicitly create a PersonalFileHandler that you are explicit closing that PersonalFileHandler before you create a second new PersonalFileHandler.
Loggers are subject to garbage collection. The line:
Logger.getLogger(clazz).addHandler(new PersonalFileHandler());
Is subject to garbage collection unless the code elsewhere as already pinned that logger in memory. This can cause log files to be created, locked, and empty.
Suppose I have 2 web applications (A & B) are hosted in the same weblogic server. I define a logging.properties file under /WEB-INF in each web application. The properties file defines a set of log levels for different classes and a file Handler which webapp A writes log to A.log, and webapp B writes log B.log. Standard java.util.logging package is used for logging.
A servlet context listener is defined such that the logging.properties file is read when the context initalized. The code fragment is as following:
InputStream is = sCtx.getResourceAsStream("/WEB-INF/logging.properties");
LogManager logManager = LogManager.getLogManager();
logManager.readConfiguration(is);
Logger rootLogger = Logger.getLogger("");
SysLogFileHandler fileHandler;
try
{
String location = SysLogFileHandler.getSysLogFilePath();
String fileName = SysLogFileHandler.LOG_FILE_PREFIX + "%d.log";
fileHandler = new SysLogFileHandler(location + File.separator + fileName, true);
fileHandler.setEncoding(Constant.DEFAULT_CHARSET);
fileHandler.setLevel(Level.ALL);
rootLogger.addHandler(fileHandler);
}
catch (Exception e)
{
e.printStackTrace();
}
I expect logs from webapp A write to A.log only, and webapp B write to B.log only. However, the outcome is not as expected. All logs from A & B are written to either 1 log file only, depends on which webapp starts at last.
May I ask what's the proper way of having separate log files in webapp environment?
If you are using the default LogManager class then calling readConfiguration will reset the logging configuration.
One solution is to use or build a new LogManager that is sensitive to the web classloader like org.apache.juli.ClassLoaderLogManager and start the server with that log manager.
I am trying to log data from my project into files based on the input parameter. My project has 5 classes of which 3 contain log messages.
I used the following code to configure log4j.
public static void configureLog4j(String log4j,String logs,String timeStamp) throws IOException {
PropertyConfigurator.configure(log4j);
FileAppender fileapp = (FileAppender) Logger.getRootLogger().getAppender("FILE");
if(fileapp != null)
logger.removeAppender(fileapp);
String filename = logs + "/test_" + info + "_" + timeStamp;
fileapp.setFile(filename);
fileapp.setLayout(new PatternLayout("%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n"));
fileapp.setWriter(new FileWriter(new File(fileapp.getFile())));
Logger.getRootLogger().addAppender(fileapp);
}
info represent name of the user. Now once I configure this in the beginning of the applications only two classes are writing logs in the file the third file which contains code to send & receive data does not write the logs to the log file. Is there any thing I am missing here.
Please help me with this issue.
Chances are that the third class is already logging before you have a chance to configure your logger. This is one reason why I switched to logback: It has a much more powerful (and better documented) config file format.
The code above also contains a problem:
if(fileapp != null)
logger.removeAppender(fileapp);
logger isn't defined anywhere and fileapp must be non-null or you'd get NPEs later.
Please be insure that your third class should not logging before configuration.
This project has been handed down to me, so I do not know much about it. There is a method where log (java.util.logging.Logger) is used and it creates two log files:
First file: fileName.log
Second file: fileName.log.lck
In Linux when I do lsof, I see these two files as open. How do I close these two files?
The reason why I want to close these files is this method is run multiple times a day and after couple of weeks the number of open files reaches a limit (around 1000), at which point our system stops working. When we restart our process ("Job Controller" which does the logging) the number of log files open goes to 0 and it works again.
This is what's been done to do logging
private static Logger log = Logger.getLogger(MyClass.class.getPackage().getName());
try{
log.logp(Level.SEVERE, "com.MyClass", "run", "It failed");
}
This is what I tried to do to close the files in the finally block but it didn't work
finally{
Handler[] handler = log.getHandlers();
for(Handler h: handler){
h.close();
}
}
I simply use:
LogManager.getLogManager().reset();
this will cancel all your log settings (log file path, file name pattern, formatter...) but it will stop using the logger close the lock file and release logger to
First solution
If you do not want to modify your code use: How to send java.util.logging to log4j?
java.util.logging.Logger to Logback using SLF4J?
I use log4j or logback. Both have Rolling File Appender (old files are removed) or Date/Time File appender.
Second solution
For logging the best usage is rolling file.
String filePattern = " fileName%.log";
int limit = 1000 * 1000; // 1 Mb
int numLogFiles = 3;
FileHandler fh = new FileHandler(filePattern, limit, numLogFiles);
// Add to logger
Logger logger = Logger.getLogger(MyClass.class.getPackage().getName());
logger.addHandler(fh);
I do not know if you can add globally file handler.
We're recently switched over to Log4J from JUL (java.util.Logging) because I wanted to add additional log files for different logging levels.
We have the option in the program to optionally append a value and a date/time stamp to the log file name at the (for all intents and purposes) end of the program's execution.
Because JUL seemed to open and close the file as needed to write to the file, it wasn't locked and we could simply use .renameTo() to change the filename.
Now, using Log4J, that file is left open and is locked, preventing us from renaming the file(s).
I can't decide the name of the file before I configure the logging because the property file containing the options for renaming is some time after the logging is needed (this is why we renamed it at the end of the program).
Do you have any suggestions as to how this can be achieved?
Would Logback and/or SLF4J help or hinder this?
I have sort of worked around the issue by using a system parameter in the log4j properties file, setting the property and then reloading the property file.
This allows me to change the name of the log file to something else at the end of the run, and then rename the old files.
It's inelegant, and very much of a kludge, so I would like to avoid this as it also leaves these temporary files around after the run.
One surefire approach would be to implement your own log4j Appender, perhaps based on the FileAppender ( http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/FileAppender.html ). Add your own specialized API to request the file be renamed.
I haven't tried this yet, but the tact I would take would be to use the underlying API setFile(...): http://www.jdocs.com/log4j/1.2.13/org/apache/log4j/FileAppender.html#M-setFile%28String,boolean,boolean,int%29
For example:
public class RenamingFileAppender extends FileAppender {
...
/** fix concurrency issue in stock implementation **/
public synchronized void setFile(String file) {
super.setFile(file);
}
public synchronized void renameFile(String newName) {
// whole method is synchronized to avoid losing log messages
// implementation can be smarter in having a short term queue
// for any messages that arrive while file is being renamed
File currentFile = new File(this.fileName);
File newFile = new File(newName);
// do checks to ensure current file exists, can be renamed etc.
...
// create a temp file to use while current log gets renamed
File tempFile = File.createTempFile("renaming-appender", ".log");
tempFile.deleteOnExit();
// tell underlying impl to use temporary file, so current file is flushed and closed
super.setFile(tempFile.getAbsolutePath(), false, this.bufferedIO, this.bufferSize);
// rename the recently closed file
currentFile.renameTo(newFile);
// now go back to the original log contents under the new name. Note append=true
super.setFile(newFile.getAbsolutePath(), true, this.bufferedIO, this.bufferSize);
}
Consider using a shutdown hooks, and renaming the file there...
http://onjava.com/pub/a/onjava/2003/03/26/shutdownhook.html
http://www.developerfeed.com/threads/tutorial/understanding-java-shutdown-hook
http://download.oracle.com/javase/1.4.2/docs/guide/lang/hook-design.html