OK, I'll ease your agony. How are we going to ask Spring to pollute our log files with its log output, provided we use SLF4J as a facade and, say, Log4J as implementation?
I assume you use maven 2 as build tool. The solution should work for Spring 2 and 3.
So here is the plan. First we use a nice library jcl-over-slf4j, which implements the public API of JCL but using SLF4J underneath. Then we use another nice library slf4j-log4j12 to tell SLF4J to use Log4j as its underlying logging framework. Apart from these two dependencies we obviously need two more: SLF4J itself (slf4j-api) and Log4J itself (log4j). So we end up with following dependencies config in maven pom:
<?xml version="1.0"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
...
<dependencies>
...
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.6.3</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.6.3</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jcl-over-slf4j</artifactId>
<version>1.6.3</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.16</version>
<scope>runtime</scope>
</dependency>
</dependencies>
</project>
But before celebrating the victory we have another thing left to solve. Removing commons-logging from classpath. Algorithm is following:
- make sure commons-logging is not directly specified in your pom as dependency
- run mvn dependency:tree and search for commons-logging in the output
- if not found goto 6
- for the higher-level dependency which brings commons-logging add the following configuration in pom:
... <dependencies> <dependency> <groupId>...</groupId> <artifactId>...</artifactId> <version>...</version> <exclusions> <exclusion> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> </exclusion> </exclusions> </dependency> </dependencies> ... - goto 2
- get some champagne and start celebrating
Now you can comfortably use SLF4J with Spring logging enabled.
Useful links:
http://blog.springsource.com/2009/12/04/logging-dependencies-in-spring/
http://stackoverflow.com/questions/3387441/how-do-i-configure-spring-and-slf4j-so-that-i-can-get-logging
