slf4j
Java的简单日志Facade (SLF4J)充当各种日志框架的简单Facade或抽象 (e.g. java.util.logging, logback, log4j)
允许最终用户在部署时插入所需的日志框架。
log4j2
Apache Log4j 2是Log4j的升级版,在其前身Log4j 1.x的基础上提供了重大改进。
并提供了Logback中可用的许多改进,同时修复了Logback架构中的一些固有问题。
只需使用log4j2而不是log4j和logback,原因如下。
-
Log4j 1。x和Logback将在重新配置时丢失事件。Log4j 2则不会。
-
在多线程场景下,异步logger具有10倍高的吞吐量和
延迟比Log4j 1低几个数量级。x和Logback。
- Log4jX有已知的死锁问题。其中许多在Logback中是固定的,但是
许多Logback类仍然需要相当高级别的同步。
Hello world
- pom.xml
<dependencies>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-api</artifactId>
<version>2.6.1</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>2.6.1</version>
</dependency>
</dependencies>
- App.java
// Import log4j classes.
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.LogManager;
public class App {
static final Logger logger = LogManager.getLogger(App.class);
public static void main(String[] args) {
logger.trace("Entering application.");
Bar bar = new Bar();
if (!bar.doIt()) {
logger.error("Didn't do it.");
}
logger.trace("Exiting application.");
}
}
- Bar.java
public class Bar {
static final Logger logger = LogManager.getLogger(Bar.class.getName());
public boolean doIt() {
logger.entry();
logger.error("Did it again!");
return logger.exit(false);
}
}
- result
ERROR StatusLogger No log4j2 configuration file found. Using default configuration: logging only errors to the console.
11:11:34.539 [main] ERROR com.ryo.logger.Bar - Did it again!
11:11:34.540 [main] ERROR com.ryo.logger.App - Didn't do it.
Process finished with exit code 0
- add log4j2.xml as following into classpath
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
<Appenders>
<Console name="Console" target="SYSTEM_OUT">
<PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
</Console>
</Appenders>
<Loggers>
<Root level="trace">
<AppenderRef ref="Console"/>
</Root>
</Loggers>
</Configuration>
- and the result is:
11:22:58.433 [main] TRACE com.ryo.logger.App - Entering application.
11:22:58.437 [main] TRACE com.ryo.logger.Bar - entry
11:22:58.438 [main] ERROR com.ryo.logger.Bar - Did it again!
11:22:58.438 [main] TRACE com.ryo.logger.Bar - exit with(false)
11:22:58.438 [main] ERROR com.ryo.logger.App - Didn't do it.
11:22:58.438 [main] TRACE com.ryo.logger.App - Exiting application.
Process finished with exit code 0
Additivity
也许需要消除除’ com.ryo.logger.Bar ‘之外的所有TRACE输出,
解决方案是向配置中添加一个新的记录器定义
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
<Appenders>
<Console name="Console" target="SYSTEM_OUT">
<PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
</Console>
</Appenders>
<Loggers>
<Logger name="com.ryo.logger.Bar" level="trace">
<AppenderRef ref="Console"/>
</Logger>
<Root level="error">
<AppenderRef ref="Console"/>
</Root>
</Loggers>
</Configuration>
- result
12:11:43.095 [main] TRACE com.ryo.logger.Bar - entry
12:11:43.095 [main] TRACE com.ryo.logger.Bar - entry
12:11:43.096 [main] ERROR com.ryo.logger.Bar - Did it again!
12:11:43.096 [main] ERROR com.ryo.logger.Bar - Did it again!
12:11:43.096 [main] TRACE com.ryo.logger.Bar - exit with(false)
12:11:43.096 [main] TRACE com.ryo.logger.Bar - exit with(false)
12:11:43.096 [main] ERROR com.ryo.logger.App - Didn't do it.
Process finished with exit code 0
Notice that the trace messages from ‘com.ryo.logger.Bar’ appear twice.
change
<Logger name="com.ryo.logger.Bar" level="trace">
<AppenderRef ref="Console"/>
</Logger>
into
<Logger name="com.ryo.logger.Bar" level="trace" additivity="false">
<AppenderRef ref="Console"/>
</Logger>
and result will be
12:16:34.921 [main] TRACE com.ryo.logger.Bar - entry
12:16:34.923 [main] ERROR com.ryo.logger.Bar - Did it again!
12:16:34.923 [main] TRACE com.ryo.logger.Bar - exit with(false)
12:16:34.923 [main] ERROR com.ryo.logger.App - Didn't do it.
Process finished with exit code 0
一旦事件到达将其相加性设置为false的记录器,该事件将不会传递给其任何父记录器。
不管它们的可加性设置如何。
给定记录器的每个启用的日志记录请求将被转发到该记录器的LoggerConfig中的所有appeners以及LoggerConfig的父appeners。
可以通过在配置文件中的Logger声明中设置 additivity="false"
来覆盖此默认行为,以便Appender累积不再是加法。
Use with junit
import junit.framework.TestCase;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
public class BaseTest extends TestCase {
protected static final Logger logger = LogManager.getLogger(BaseTest.class);
}
Normal Example
- 用户目录占位符:
${sys:user.home}
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="off" monitorInterval="1800">
<properties>
<property name="LOG_HOME">src/log</property>
<property name="BACKUP_HOME">${LOG_HOME}/backup</property>
<property name="SERVER_NAME">global</property>
<!--file names-->
<property name="CONTROLLER_FILE_NAME">controller</property>
</properties>
<Appenders>
<Console name="Console" target="SYSTEM_OUT">
<PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss.SSS} %-5level [%t] %logger{36}:%L - %msg%n"/>
</Console>
<RollingRandomAccessFile name="DevLog" fileName="${LOG_HOME}/${SERVER_NAME}"
filePattern="${LOG_HOME}/${SERVER_NAME}.log-%d{yyyy-MM-dd-HH}.log">
<PatternLayout pattern="%date{yyyy-MM-dd HH:mm:ss.SSS} %level [%thread][%file:%line] - %msg%n" />
<Policies>
<TimeBasedTriggeringPolicy interval="1" modulate="true" />
<SizeBasedTriggeringPolicy size="10 MB"/>
</Policies>
</RollingRandomAccessFile>
<RollingRandomAccessFile name="ControllerLog"
fileName="${LOG_HOME}/${CONTROLLER_FILE_NAME}.log"
filePattern="${LOG_HOME}/$${date:yyyy-MM}/${CONTROLLER_FILE_NAME}-%d{yyyy-MM-dd}-%i.log.gz">
<PatternLayout
pattern="%date{yyyy-MM-dd HH:mm:ss.SSS} %-5level [%t][%file:%L] - %msg%n"/>
<Policies>
<TimeBasedTriggeringPolicy/>
<SizeBasedTriggeringPolicy size="10 MB"/>
</Policies>
<DefaultRolloverStrategy max="20"/>
</RollingRandomAccessFile>
</Appenders>
<Loggers>
<Logger name="com.ryo.interceptor.ControllerLogInterceptor" level="INFO" additivity="false">
<AppenderRef ref="ControllerLog"/>
<AppenderRef ref="Console"/>
</Logger>
<Root level="INFO">
<AppenderRef ref="DevLog"/>
<AppenderRef ref="Console"/>
</Root>
</Loggers>
</Configuration>
Architecture
Log Levels
过滤级别:
Event Level | LoggerConfig Level | ||||||
---|---|---|---|---|---|---|---|
TRACE | DEBUG | INFO | WARN | ERROR | FATAL | OFF | |
ALL | YES | YES | YES | YES | YES | YES | NO |
TRACE | YES | NO | NO | NO | NO | NO | NO |
DEBUG | YES | YES | NO | NO | NO | NO | NO |
INFO | YES | YES | YES | NO | NO | NO | NO |
WARN | YES | YES | YES | YES | NO | NO | NO |
ERROR | YES | YES | YES | YES | YES | NO | NO |
FATAL | YES | YES | YES | YES | YES | YES | NO |
OFF | NO | NO | NO | NO | NO | NO | NO |
Layout
通常情况下,用户不仅希望自定义输出目的地,还希望自定义输出格式。
例如,带有转换模式 %r [%t] %-5p %c - %m%n
的PatternLayout将输出类似于以下内容:
176 [main] INFO org.foo.Bar - Located nearest gas station.
layout用于各种用例,如JSON、XML、HTML和Syslog(包括新的RFC 5424版本)。
参数 | 说明 | 例子 | |
---|---|---|---|
%c
|
列出logger名字空间的全称,如果加上{<层数>}表示列出从最内层算起的指定层数的名字空间 |
log4j配置文件参数举例
|
输出显示媒介
|
假设当前logger名字空间是"a.b.c" | |||
%c | a.b.c | ||
%c{2} | b.c | ||
%20c | (若名字空间长度小于20,则左边用空格填充) | ||
%-20c | (若名字空间长度小于20,则右边用空格填充) | ||
%.30c | (若名字空间长度超过30,截去多余字符) | ||
%20.30c | (若名字空间长度小于20,则左边用空格填充;若名字空间长度超过30,截去多余字符) | ||
%-20.30c | (若名字空间长度小于20,则右边用空格填充;若名字空间长度超过30,截去多余字符) | ||
%C
|
列出调用logger的类的全名(包含包路径) | 假设当前类是"org.apache.xyz.SomeClass" | |
%C | org.apache.xyz.SomeClass | ||
%C{1} | SomeClass | ||
%d
|
显示日志记录时间,{<日期格式>}使用ISO8601定义的日期格式 | %d{yyyy/MM/dd HH:mm:ss,SSS} | 2005/10/12 22:23:30,117 |
%d{ABSOLUTE} | 22:23:30,117 | ||
%d{DATE} | 12 Oct 2005 22:23:30,117 | ||
%d{ISO8601} | 2005-10-12 22:23:30,117 | ||
%F
|
显示调用logger的源文件名 | %F | MyClass.java |
%l
|
输出日志事件的发生位置,包括类目名、发生的线程,以及在代码中的行数 | %l | MyClass.main(MyClass.java:129) |
%L
|
显示调用logger的代码行 | %L | 129 |
%m
|
显示输出消息 | %m | This is a message for debug. |
%M
|
显示调用logger的方法名 | %M | main |
%n
|
当前平台下的换行符 | %n | Windows平台下表示rn UNIX平台下表示n |
%p
|
显示该条日志的优先级 | %p | INFO |
%r
|
显示从程序启动时到记录该条日志时已经经过的毫秒数 | %r | 1215 |
%t
|
输出产生该日志事件的线程名 | %t | MyClass |
%x
|
按NDC(Nested Diagnostic Context,线程堆栈)顺序输出日志 | 假设某程序调用顺序是MyApp调用com.foo.Bar | |
%c %x - %m%n | MyApp - Call com.foo.Bar. com.foo.Bar - Log in Bar MyApp - Return to MyApp. |
||
%X
|
按MDC(Mapped Diagnostic Context,线程映射表)输出日志。通常用于多个客户端连接同一台服务器,方便服务器区分是那个客户端访问留下来的日志。 | %X{5} | (记录代号为5的客户端的日志) |
%%
|
显示一个百分号 | %% | % |
Slf4j
虽然合并会降低速度,但是有时需要支持这种标准。
<!-- log配置:Log4j2 + Slf4j -->
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-api</artifactId>
<version>2.2</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>2.2</version>
</dependency>
<dependency> <!-- 桥接:告诉Slf4j使用Log4j2 -->
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-slf4j-impl</artifactId>
<version>2.2</version>
</dependency>
<dependency> <!-- 桥接:告诉commons logging使用Log4j2 -->
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-jcl</artifactId>
<version>2.2</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.10</version>
</dependency>