Apache Commons-logging+log4j配置
1) 首先在classpath下寻找自己的配置文件commons-logging.properties，如果找到，则使用其中定义的Log实现类；
2) 如果找不到commons-logging.properties文件，则在查找是否已定义系统环境变量org.apache.commons.logging.Log，找到则使用其定义的Log实现类；
如果在Tomact中可以建立一个叫 ：CATALINA_OPTS 的环境变量
给 他的 值 ： - Dorg.apache.commons.logging.Log = org.apache.commons.logging.impl.SimpleLog - Dorg.apache.commons.logging.simplelog.defaultlog = warn
3) 否则，查看classpath中是否有Log4j的包，如果发现，则自动使用Log4j作为日志实现类；
4) 否则，使用JDK自身的日志实现类（JDK1.4以后才有日志实现类）；
5) 否则，使用commons-logging自己提供的一个简单的日志实现类SimpleLog；
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#commons-logging.properties文件配置信息
# org.apache.commons.logging.Log=org.apache.commons.logging.impl.SimpleLog
# Must be one of ("trace", "debug", "info", "warn", "error", or "fatal").
#log4j
org.apache.commons.logging.Log=org.apache.commons.logging.impl.Log4JLogger
#JDK5 Logger
#org.apache.commons.logging.Log=org.apache.commons.logging.impl.Jdk14Logger
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log.fatal(Object message);
log.fatal(Object message, Throwable t);
log.error(Object message);
log.error(Object message, Throwable t);
log.warn(Object message);
log.warn(Object message, Throwable t);
log.info(Object message);
log.info(Object message, Throwable t);
log.debug(Object message);
log.debug(Object message, Throwable t);
log.trace(Object message);
log.trace(Object message, Throwable t);
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log.isFatalEnabled();
log.isErrorEnabled();
log.isWarnEnabled();
log.isInfoEnabled();
log.isDebugEnabled();
log.isTraceEnabled();
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private static Log
log =
LogFactory.
getLog(Test.
class);
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log.debug("Debug info.");
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- import org.apache.commons.logging.Log;
- import org.apache.commons.logging.LogFactory;
- public class TestLog {
- private static Log log = LogFactory.getLog(TestLog.class);
- public void log() {
- log.debug("Debug info.");
- log.info("Info info");
- log.warn("Warn info");
- log.error("Error info");
- log.fatal("Fatal info");
- }
- public static void main(String[] args) {
- System.out.println("log obj = " + log);
- TestLog test = new TestLog();
- test.log();
- }
- }
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
public class TestLog {
private static Log log = LogFactory.getLog(TestLog.class);
public void log() {
log.debug("Debug info.");
log.info("Info info");
log.warn("Warn info");
log.error("Error info");
log.fatal("Fatal info");
}
public static void main(String[] args) {
System.out.println("log obj = " + log);
TestLog test = new TestLog();
test.log();
}
}
log obj = org.apache.commons.logging.impl.Jdk14Logger@173a10f
2009-11-19 22:48:48 TestLog log
信息: Info info
2009-11-19 22:48:49 TestLog log
警告: Warn info
2009-11-19 22:48:49 TestLog log
严重: Error info
2009-11-19 22:48:49 TestLog log
严重: Fatal info
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org.apache.commons.logging.Log=org.apache.commons.logging.impl.Log4JLogger
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log4j.rootLogger=info, stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
# Pattern to output the caller's file name and line number.
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n
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| log obj = org.apache.commons.logging.impl.Log4JLogger@1ffb8dc INFO [main] - Info info WARN [main] - Warn info ERROR [main] - Error info FATAL [main] - Fatal info |
如果把commons-logging.properties配置成如下：
org.apache.commons.logging.Log=org.apache.commons.logging.impl.SimpleLog
则输出：
log obj = org.apache.commons.logging.impl.SimpleLog@69b332
[INFO] TestLog - Info info
[WARN] TestLog - Warn info
[ERROR] TestLog - Error info
[FATAL] TestLog - Fatal info
为了简化配置，我们可以不使用commons-logging的配置文件，也不设置commons-logging相关的环境变量，只需log4j的包放入classpath就可以了，这样就可以完成commons-logging与Log4j的结合。如果以后不想使用log4j，只需将log4j的包从classpath中移除就可以了。 当然使用时Log4j会根据指定的日志器名（LogFactory.getLog(TestLog.class)）自动搜索classpath下log4j.properties或log4j.xml配置文件中对应的日志器，如果没有找到，可能会显示以下错误信息：
log4j:WARN No appenders could be found for logger (TestLog).
log4j:WARN Please initialize the log4j system properly.