How do I configure Spring and SLF4J so that I can get logging?

Question

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 lo

Answer 1

You'll find an example at https://github.com/mbogoevici/spring-samples/tree/master/mvc-basic/trunk. You need to include some dependencies in your POM file to enable logging.

<!-- Logging -->
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>${org.slf4j.version}</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>jcl-over-slf4j</artifactId>
        <version>${org.slf4j.version}</version>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
        <version>${org.slf4j.version}</version>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.16</version>
        <scope>runtime</scope>
    </dependency>

Answer 2

Use blow configuration for implementation of the JCL API on the classpath:

<dependencies>
       <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-context</artifactId>
          <version>3.0.0.RELEASE</version>
          <scope>runtime</scope>
          <exclusions>
             <exclusion>
                <groupId>commons-logging</groupId>
                <artifactId>commons-logging</artifactId>
             </exclusion>
          </exclusions>
       </dependency>
       <dependency>
          <groupId>org.slf4j</groupId>
          <artifactId>jcl-over-slf4j</artifactId>
          <version>1.5.8</version>
          <scope>runtime</scope>
       </dependency>
       <dependency>
          <groupId>org.slf4j</groupId>
          <artifactId>slf4j-api</artifactId>
          <version>1.5.8</version>
          <scope>runtime</scope>
       </dependency>
       <dependency>
          <groupId>org.slf4j</groupId>
          <artifactId>slf4j-log4j12</artifactId>
          <version>1.5.8</version>
          <scope>runtime</scope>
       </dependency>
       <dependency>
          <groupId>log4j</groupId>
          <artifactId>log4j</artifactId>
          <version>1.2.14</version>
          <scope>runtime</scope>
       </dependency>
    </dependencies> 

for More information check here

Answer 3

In addition to Jatin's answer:

Spring uses Jakarta Commons Logging as a logging API. In order to log to slf4j, you need to make sure commons-logging is not on the classpath. jcl-over-slf4j is a replacement jar for commons-logging.

If you're using maven, you can detect where commons-logging comes from using mvn dependency:tree and exclude it from all dependencies that require it using dependency exclusions. You might need to run mvn dependency:tree several times though, because it only shows the first occurence of a transitive dependency.

<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-context</artifactId>
  <version>${org.springframework.version}</version>
  <exclusions>
    <exclusion>
      <artifactId>commons-logging</artifactId>
      <groupId>commons-logging</groupId>
    </exclusion>
  </exclusions>
</dependency>

Answer 4

keep log4j file in default package

Answer 5

I like the logback way, and for slf4j, we do the similar config:

    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>jcl-over-slf4j</artifactId>
    </dependency>

slf4j-log4j12 will automatically introduce slf4j-api and log4j, so don't need to put so many dependencies

Answer 6

Just add lazy-init="false" to eagerly load the bean for log4j configuration in your root context. That should solve the WARN message log4j:WARN No appenders could be found for logger

Example:

<bean id="log4jInitialization" class="org.springframework.beans.factory.config.MethodInvokingFactoryBean" lazy-init="false">

A more better approach would be to have the configuration in web.xml or as a JVM parameter (-Dlog4j.configuration=.../conf/log4j.xml or with 'file:' prefix as -Dlog4j.configuration=file:conf/log4j.properties for some cases)