slf4j
Simple Logging Facade for Java
SLF4J
For Java development, I use Slf4j and Logback.
Logger logger = LoggerFactory.getLogger(HelloWorld.class);
logger.debug("Hello world.");
How to use these two libs in Clojure programs? Majority of Clojure programming doesn't has .class concept (possible of course via AOT).
What do you use for logging in Clojure?
Source: (StackOverflow)
What is the correct approach to log both a populated message and a stack trace of the exception?
logger.error(
"\ncontext info one two three: {} {} {}\n",
new Object[] {"1", "2", "3"},
new Exception("something went wrong"));
I'd like to produce an output similar to this:
context info one two three: 1 2 3
java.lang.Exception: something went wrong
stacktrace 0
stacktrace 1
stacktrace ...
slf4j version 1.6.1
Source: (StackOverflow)
My application is to be deployed on both tcServer and WebSphere 6.1. This application uses ehCache and so requires slf4j as a dependency.
As a result I've added the slf4j-api.jar (1.6) jar to my war file bundle.
The application works fine in tcServer except for the following error:
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
However, when I deploy in WebSphere I get a java.lang.NoClassDefFoundError: org.slf4j.impl.StaticLoggerBinder.
I've checked the classpaths of both application servers and there is no other slf4j jar.
Anyone any ideas what may be happening here?
Source: (StackOverflow)
I am trying to use SLF4J (with log4j binding) for the first time.
I would like to configure 3 different named Loggers that can be returned by a LoggerFactory which will log different levels and push the messages to different appenders:
- Logger 1 "FileLogger" logs DEBUG and appends to
DailyRollingFileAppender
- Logger 2 "TracingLogger" logs TRACE+ and appends to a
JmsAppender
- Logger 3 "ErrorLogger" logs ERROR+ and appends to a different
JmsAppender
Furthermore I want them configured programmatically (in Java, as opposed to XML or a log4j.properties file).
I imagine that, normally, I would define these Loggers somewhere in some bootstrapping code, like an init() method. However, because I want to use slf4j-log4j, I'm confused about where I could define loggers and make them available to the classpath.
I don't believe this is a violation of SLF4J's underlying purpose (as a facade), because my code using the SLF4J API won't ever know that these loggers exist. My code just makes normal calls to the SLF4J API, which then forwards them on to the log4j Loggers it finds on the classpath.
But how do I configure those log4j Loggers on the classpath...in Java?!
Source: (StackOverflow)
I have an existing application which does all of its logging against log4j. We use a number of other libraries that either also use log4j, or log against Commons Logging, which ends up using log4j under the covers in our environment. One of our dependencies even logs against slf4j, which also works fine since it eventually delegates to log4j as well.
Now, I'd like to add ehcache to this application for some caching needs. Previous versions of ehcache used commons-logging, which would have worked perfectly in this scenario, but as of version 1.6-beta1 they have removed the dependency on commons-logging and replaced it with java.util.logging instead.
Not really being familiar with the built-in JDK logging available with java.util.logging, is there an easy way to have any log messages sent to JUL logged against log4j, so I can use my existing configuration and set up for any logging coming from ehcache?
Looking at the javadocs for JUL, it looks like I could set up a bunch of environment variables to change which LogManager implementation is used, and perhaps use that to wrap log4j Loggers in the JUL Logger class. Is this the correct approach?
Kind of ironic that a library's use of built-in JDK logging would cause such a headache when (most of) the rest of the world is using 3rd party libraries instead.
Source: (StackOverflow)
I'm getting the following error. It seems there are multiple logging frameworks bound to sl4j. Not sure how to resolve this. Any help is greatly appreciated.
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/C:/Users/admin/.m2/repository/org/slf4j/slf4j-log4j12/1.6.4/slf4j-log4j12-1.6.4.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/C:/Users/admin/.m2/repository/org/slf4j/slf4j-log4j12/1.6.1/slf4j-log4j12-1.6.1.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
Source: (StackOverflow)
When using log4j, the Logger.log(Priority p, Object message) method is available and can be used to log a message at a log level determined at runtime. We're using this fact and this tip to redirect stderr to a logger at a specific log level.
slf4j doesn't have a generic log() method that I can find. Does that mean there's no way to implement the above?
Source: (StackOverflow)
api 1.7 and slf4j-simple as implementation. I just can't find how to configure the logging level with this combination.
Can anyone help out?
Source: (StackOverflow)
Hibernate 3.x used slf4j for logging. Hibernate 4.x uses jboss-logging. I am writing a standalone application which uses Hibernate 4, and SLF4J for logging.
How can i configure Hibernate to log to SLF4J?
If that's not possible, how can i configure Hibernate's logging at all?
The Hibernate 4.1 manual section on logging starts with the warning that it is ...
Completely out of date. Hibernate uses JBoss Logging starting in 4.0. This will get documented as we migrate this content to the Developer Guide.
... goes on to talk about SLF4J, and so is useless. Neither the getting started guide nor the developer guide talk about logging at all. Nor does the migration guide.
I have looked for documentation on jboss-logging itself, but i haven't been able to find any at all. The GitHub page is silent, and JBoss's community projects page doesn't even list jboss-logging. I wondered if th project's bug tracker might have any issues relating to providing documentation, but it doesn't.
The good news is that when using Hibernate 4 inside an application server, such as JBoss AS7, logging is largely taken care of for you. But how can i configure it in a standalone application?
Source: (StackOverflow)
It seems that log4j has some class loading issues (among others) and it seems to me the trend is to move out of log4j toward slf4j. (Hibernate stopped using the first in favor of the latter)
- Is it true?
- What are the main issues in log4j that slf4j solves?
- Is slf4j the final word or is there even a better "the next next log4j" industry standard?
This is my first question here, so please be gentle
Update:
- So this answer by delfuego confuses me, can you accept / object it?:
You appear to have stumbled upon the
major problem with log4j (and the
Apache Commons Logging library),
namely that they have a ridiculously
hard time discovering and interacting
with the right classloaders as they're
being used. There's a very dense
explanation, complete with examples,
here; the take-home message is that
one of the primary driving forces for
the new logging framework SLF4J was to
eliminate these issues entirely. You
might want to swap it in and see if
your life is made any easier.
Source: (StackOverflow)
I've got a maven & spring app that I want logging in. I'm keen to use SLF4J.
I want to put all my config files into a directory {classpath}/config including log4j.xml and then init using a spring bean.
e.g.
<bean id="log4jInitialization" class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
<property name="targetClass" value="org.springframework.util.Log4jConfigurer"/>
<property name="targetMethod" value="initLogging"/>
<property name="arguments">
<list>
<value>classpath:config/log4j.xml</value>
</list>
</property>
</bean>
However I get this warning and no logging.
log4j:WARN No appenders could be found for logger (org.springframework.context.support.ClassPathXmlApplicationContext).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
I've googled around and can't find a simple example on setting this up. Any ideas?
Source: (StackOverflow)
I'm trying to run the sample tiles example given here.
Below is my POM.xml:
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.tiles</groupId>
<artifactId>tiles-api</artifactId>
<version>2.1.2</version>
</dependency>
<dependency>
<groupId>org.apache.tiles</groupId>
<artifactId>tiles-core</artifactId>
<version>2.1.2</version>
</dependency>
<dependency>
<groupId>org.apache.tiles</groupId>
<artifactId>tiles-jsp</artifactId>
<version>2.1.2</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.5.2</version>
</dependency>
When I'm trying to run the example the below error is thrown:
Sep 17, 2010 11:59:43 PM org.apache.catalina.core.StandardContext listenerStart
SEVERE: Error configuring application listener of class org.apache.tiles.web.startup.TilesListener
java.lang.NoClassDefFoundError: org/slf4j/impl/StaticLoggerBinder
at org.slf4j.LoggerFactory.<clinit>(LoggerFactory.java:60)
at org.apache.commons.logging.impl.SLF4JLogFactory.getInstance(SLF4JLogFactory.java:155)
at org.apache.commons.logging.impl.SLF4JLogFactory.getInstance(SLF4JLogFactory.java:131)
at org.apache.commons.logging.LogFactory.getLog(LogFactory.java:685)
at org.apache.tiles.web.startup.TilesListener.<init>(TilesListener.java:49)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
Any idea?
I spent 30 minutes googling for this but could not find a possible sollution.
Please help me...
Source: (StackOverflow)
I have some questions about logging, more specifically about setting it up and making sure it works.
The project I'm doing will use Wicket, Spring and Hibernate. I know that Wicket and Hibernate uses Simple Logging Facade for Java (SL4J) and that Spring is using the logging component from Apache Commons.
Will they co-exist happily?
I thought I would use log4j together with both SL4J and the logging component from Apache commons, do you think that's a good idea?
Can I set up them all to output logging data into a common file?
Or should I use separate files?
Or should I store the logging messages in the database? (I'd rather not, as I find grepping etc on text files quite convenient.)
For Spring I guess I need some kind of configuration file for the Apache Commons logging component as well where I direct it to use log4j?
When I've set these up I guess to see that everything works I set the logging level to INFO as it's fairly certain that all three of the frameworks output some information in that mode? Or is there an even better way to make sure?
And my last question. In the project I'm starting, do you recommend that I use SL4J for my own logging purposes? (I thought I would use log4j directly, but that was before I learned a little bit more about logging and a lot of respectable libraries seem to choose the path of a bridge/facade for their logging needs. And if it gets us flexibility without added cost there's no reason not to do it that way.)
I'm looking forward to hearing more from you about how you are doing your logging. It's a new area for me which I'm eager to improve myself in.
Source: (StackOverflow)
What's the correct approach to log both an error message and an exception using SLF4J?
I've tried doing this but the exception stack trace is never printed:
logger.error("Unable to parse data {}", inputMessage, e);
In this case I want to populate {} with the inputMessage as well as logging out the exception stacktrace.
The only way I can see to do this would be to do this:
logger.error("Unable to parse data " + inputMessage, e);
which is not pretty.
Source: (StackOverflow)
I'm attempting to upgrade from Hibernate 3.2 to 3.4, which apparently uses slf4j. Our project currently uses log4j. So my assumption is that I should be using the slf4j-log4j12 wrapped implementation.
The Maven slf4j dependency is:
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.5.6</version>
</dependency>
While the log4j dependency is:
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.15</version>
</dependency>
Both slf4j-log4j12 and log4j reference the latest version (that I could find in the Maven repository). When I run my app, Hibernate fails in its logging:
java.lang.NoSuchFieldError: name
at org.slf4j.impl.Log4jLoggerAdapter.<init>(Log4jLoggerAdapter.java:75)
at org.slf4j.impl.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:75)
at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:103)
at org.hibernate.cfg.Configuration.<clinit>(Configuration.java:163)
...
What am I missing?
Edit 1: If I remove the log4j dependency from my pom.xml I get the error:
java.lang.IllegalAccessError: tried to access field org.slf4j.impl.StaticLoggerBinder.SINGLETON from class org.slf4j.LoggerFactory
at org.slf4j.LoggerFactory.<clinit>(LoggerFactory.java:60)
at org.hibernate.cfg.Configuration.<clinit>(Configuration.java:163)
...
Edit 2: This blog claims the problem is caused by hibernate annotations shipping with the wrong version of slf4j-api.jar.
Source: (StackOverflow)