查看“Log4j”的源代码

Apache Log4j is a versatile, industrial-grade Java logging framework composed of an API, its implementation, and components to assist the deployment for various use cases.

https://logging.apache.org/log4j/2.x/

* 控制日志信息输送的目的地是控制台、文件、GUI 组件，甚至是套接口服务器、NT 的事件记录器、UNIX Syslog 守护进程等
* 控制每一条日志的输出格式
* 通过定义每一条日志信息的级别，更加细致地控制日志的生成过程
ALL < DEBUG < INFO < WARN < ERROR < FATAL < OFF

=== pom.xml ===
 <!-- https://mvnrepository.com/artifact/log4j/log4j -->
 <dependency>
     <groupId>log4j</groupId>
     <artifactId>log4j</artifactId>
     <version>1.2.17</version>
 </dependency>

=== log4j.properties ===
 log4j.rootLogger=INFO,stdout
 # 第一段表示输出级别, stdout,logfile 表示输出方式，与下面对应
 # log4j.rootLogger=Error,stdout,logfile
 
 # stdout
 log4j.appender.stdout=org.apache.log4j.ConsoleAppender
 log4j.appender.stdout.Target=System.out
 log4j.appender.stdout.Threshold=DEBUG
 log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
 log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] %m%n
 
 # logfile
 log4j.appender.logfile=org.apache.log4j.RollingFileAppender
 log4j.appender.logfile.File=log/system.log
 log4j.appender.logfile.MaxFileSize=10mb
 log4j.appender.logfile.Threshold=Error
 log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
 log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] %m%n
 
 # Level
 log4j.logger.org.apache.kafka=Error
 
 <small># 可以指定类输出级别
 log4j.logger.org.mybatis=DEBUG
 log4j.logger.java.sql=DEBUG
 log4j.logger.java.sql.Statement=DEBUG
 log4j.logger.java.sql.ResultSet=DEBUG
 log4j.logger.java.sql.PreparedStatement=DEBUG
 
 如 kafka 中会大量输出 debug 信息，可以指定输出级别或关闭(=OFF)：
 log4j.logger.org.apache.kafka.clients=Error
 log4j.logger.org.apache.kafka.common=Error</small>

=== 输出日志类 ===
 private static final Logger logger = Logger.getLogger(CLASSNAME.class)
 ...
 logger.info("information...")

 public static void log(Object log1) {
     Logger logger = Logger.getLogger(Thread.currentThread().getStackTrace()[2].getClassName());
     logger.info(log1);
 }

== slf4j ==
 import org.apache.log4j.PropertyConfigurator;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 public class BASE {
     public static final String VERSION = "v1.21";
     static {
         PropertyConfigurator.configure("config/log4j.properties");
     }
     private static final Logger logger = LoggerFactory.getLogger(BASE.class);
 
     public static void test(Object log1) {
         logger.info(log1.toString());
         logger.warn(log1.toString());
     }
 }

== See Also ==
# [https://www.cnblogs.com/mytJava/p/13143335.html log4j详解及log4j.properties配置]


[[分类:Develop]]
[[分类:Java]]