log4j多线程以及分文件输出日志
前段时间项目里因为多线程的问题对log4j进行了一下学习，今天有空汇总一下。
需求是有一个多线程程序，需要对每个线程的日志单独按级别存储。如下图所示。
项目代码不方便发出，简单写一个demo。
import org.apache.logging.log4j.LogManager; import org.apache.logging.log4j.Logger; import org.apache.logging.log4j.ThreadContext; public class TestLog { private static Logger log = LogManager.getLogger(TestLog.class); public static void main(String[] args) { Thread[] threads = new Thread[10]; for(int i=0;i<10;i++){ threads[i] = new TestThread("-"+i); } for(Thread thread : threads) { thread.start(); } } }
import org.apache.logging.log4j.LogManager; import org.apache.logging.log4j.Logger; import org.apache.logging.log4j.ThreadContext; class TestThread extends Thread { private static Logger log = LogManager.getLogger(TestLog.class); public TestThread(String name) { super(name); } @Override public void run() { try { System.out.println(Thread.currentThread().getName()); log.info(Thread.currentThread().getName()); log.error("error:"+Thread.currentThread().getName()); } catch (Exception e) { e.printStackTrace(); } } }
一、log4j
1.每个线程中输出一份文件（此方法不通，留痕）
方法一是可以通过filter进行过滤。
但是考虑到需要对不同线程的日志按级别进行输出，还需要进一步改造。
因此考虑，首先在log4j.properties中对日志进行过滤，，将不同级别的日志输出到不同文件。可参考https://blog.csdn.net/liuxiao723846/article/details/69295428
log4j.rootLogger=info,stdout,infolog,errorlog log4j.appender.stdout=org.apache.log4j.ConsoleAppender log4j.appender.stdout.Target=System.out log4j.appender.stdout.layout=org.apache.log4j.PatternLayout log4j.appender.stdout.layout.ConversionPattern=[%d{MM-dd HH:mm:ss}] [%p] [%c:%L] %m%n log4j.appender.infolog = org.apache.log4j.DailyRollingFileAppender log4j.appender.infolog.Threshold = INFO log4j.appender.infolog.File = /data/logs/logtest/test.log log4j.appender.infolog.layout = org.apache.log4j.PatternLayout log4j.appender.infolog.layout.ConversionPattern = [%d{MM-dd HH:mm:ss}] [%p] [%c:%L] %m%n log4j.appender.infolog.filter.infoFilter = org.apache.log4j.varia.LevelRangeFilter log4j.appender.infolog.filter.infoFilter.LevelMin = INFO log4j.appender.infolog.filter.infoFilter.LevelMax = INFO log4j.appender.warnlog = org.apache.log4j.DailyRollingFileAppender log4j.appender.warnlog.Threshold = WARN log4j.appender.warnlog.File = /data/logs/logtest/test_warn.log log4j.appender.warnlog.layout = org.apache.log4j.PatternLayout log4j.appender.warnlog.layout.ConversionPattern = [%d{MM-dd HH:mm:ss}] [%p] [%c:%L] %m%n log4j.appender.warnlog.filter.warnFilter = org.apache.log4j.varia.LevelRangeFilter log4j.appender.warnlog.filter.warnFilter.LevelMin = WARN log4j.appender.warnlog.filter.warnFilter.LevelMax=WARN
然后，在每个线程中对输出的日志名称进行重命名。对TestThread类进行改造
class TestThread extends Thread { private static final Logger log = Loggger.getLogger(TestLog.class); public TestThread(String name) { super(name); } @Override public void run() { try { FileAppender appender = (FileAppender) log.getRootLogger().getAppender("errorlog"); appender.setFile("C:/Test/SystemOutError"+Thread.currentThread().getName()+".log"); appender.activateOptions(); FileAppender appender = (FileAppender) log.getRootLogger().getAppender("infolog"); appender.setFile("C:/Test/SystemOut"+Thread.currentThread().getName()+".log"); appender.activateOptions(); System.out.println(Thread.currentThread().getName()); log.info(Thread.currentThread().getName()); log.error("error:"+Thread.currentThread().getName()); } catch (Exception e) { e.printStackTrace(); } } }
但是，该方法能够按照线程生成不同的文件，并且文件分为不同的级别，例如下图。但是打开后发现error的内容都会存储在thread1的文件中，thread2中为空文件。
搜索了一下是因为log4j是单例模式，参考https://blog.csdn.net/guan0005/article/details/84139142，摘录其中一段。
但log4j中有个陷阱：单例模式。在log4j中，配置的每个Logger，都只有一个实例。即在不同线程中，取到的同名Logger，全都是同一个实例。那么，之前的思路就 行不通了。除非为每个线程配置一个特定的Logger，或者配置一定数量的Logger，组成一个Logger池，各线程争用Logger池中的Logger实例。但这两种方法要么不够灵活，要么逻辑复杂，并不是我想要的方案。
分析：
既然问题出在单例模式上，那我们只要在创建子线程的时候，为线程创建一个私有的Logger实例，不就行了吗。遗憾的是，log4j并没有提供创建全新Logger实例的接口给我们使用，Logger对象只能通过Logger.getLogger(*)方法获取，而不能new一个Logger对象。怎么办？只能重写Logger类，或创建Logger的子类了。
上篇文章中给出了创建子类的方式，后续给出。
2.threadlocal
待补充。
二、log4j2
重点参考这篇文章https://my.oschina.net/u/2300159/blog/887687
导入两个包
<dependencies>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-api</artifactId>
<version>2.12.0</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>2.12.0</version>
</dependency>
</dependencies>
配置log4j2.xml
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="OFF">
<Appenders>
<Routing name="Routing">
<Routes pattern="$${ctx:ROUTINGKEY}">
<!-- This route is chosen if ThreadContext has a value for ROUTINGKEY
(other than the value 'special' which had its own route above).
The value dynamically determines the name of the log file. -->
<Route>
<RollingFile name="Rolling-${ctx:ROUTINGKEY}" fileName="logs/SystemOut-${ctx:ROUTINGKEY}.log"
filePattern="./logs/${date:yyyy-MM}/${ctx:ROUTINGKEY}-SystemOut-%d{yyyy-MM-dd}-%i.log.gz">
<PatternLayout>
<pattern>%d{ISO8601} [%t] %p %c{3} - %m%n</pattern>
</PatternLayout>
<Policies>
<TimeBasedTriggeringPolicy interval="6" modulate="true"/>
<SizeBasedTriggeringPolicy size="10 MB"/>
</Policies>
</RollingFile>
</Route>
</Routes>
</Routing>
<!--很直白，Console指定了结果输出到控制台-->
<Console name="ConsolePrint" target="SYSTEM_OUT">
<PatternLayout pattern="%d{yyyy.MM.dd HH:mm:ss z} %t %-5level %class{36} %L %M - %msg%xEx%n"/>
</Console>
</Appenders>
<Loggers>
<!-- 级别顺序（低到高）：TRACE < DEBUG < INFO < WARN < ERROR < FATAL -->
<Root level="DEBUG" includeLocation="true">
<!--AppenderRef中的ref值必须是在前面定义的appenders-->
<AppenderRef ref="Routing"/>
<AppenderRef ref="ConsolePrint"/>
</Root>
</Loggers>
</Configuration>
该xml中有一个变量${ctx:ROUTINGKEY}，此变量需要在代码中设定，对TestThread进行修改
import org.apache.logging.log4j.LogManager; import org.apache.logging.log4j.Logger; import org.apache.logging.log4j.ThreadContext; import org.apache.logging.log4j.core.appender.FileAppender; class TestThread extends Thread { private static Logger log = LogManager.getLogger(TestLog.class); public TestThread(String name) { super(name); } @Override public void run() { ThreadContext.put("ROUTINGKEY", Thread.currentThread().getName()); try { System.out.println(Thread.currentThread().getName()); log.info(Thread.currentThread().getName()); log.error("error:"+Thread.currentThread().getName()); } catch (Exception e) { e.printStackTrace(); } } }
点击运行，便可以按照线程生成日志。
该部分代码可以
2.不使用ThreadContext
首先修改xml配置
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="OFF">
<Appenders>
<Routing name="Routing">
<Routes pattern="$${thread:threadName}">
<Route>
<RollingFile name="logFile-${thread:threadName}"
fileName="logs/concurrent-${thread:threadName}.log"
filePattern="logs/concurrent-${thread:threadName}-%d{MM-dd-yyyy}-%i.log">
<PatternLayout pattern="%d %-5p [%t] %C{2} - %m%n"/>
<Policies>
<SizeBasedTriggeringPolicy size="50 MB"/>
</Policies>
<DefaultRolloverStrategy max="100"/>
</RollingFile>
</Route>
</Routes>
</Routing>
<Async name="async" bufferSize="1000" includeLocation="true">
<AppenderRef ref="Routing"/>
</Async>
<!--很直白，Console指定了结果输出到控制台-->
<Console name="ConsolePrint" target="SYSTEM_OUT">
<PatternLayout pattern="%d{yyyy.MM.dd HH:mm:ss z} %t %-5level %class{36} %L %M - %msg%xEx%n"/>
</Console>
</Appenders>
<Loggers>
<Root level="info" includeLocation="true">
<AppenderRef ref="async"/>
<AppenderRef ref="ConsolePrint"/>
</Root>
</Loggers>
</Configuration>
然后实现StrLookup
import org.apache.logging.log4j.core.LogEvent; import org.apache.logging.log4j.core.config.plugins.Plugin; import org.apache.logging.log4j.core.lookup.StrLookup; @Plugin(name = "thread", category = StrLookup.CATEGORY) public class ThreadLookup implements StrLookup { @Override public String lookup(String key) { return Thread.currentThread().getName(); } @Override public String lookup(LogEvent event, String key) { return event.getThreadName() == null ? Thread.currentThread().getName() : event.getThreadName(); } }
ThreadLookup类可以获取到代码中的线程名称，所以我们要对每个线程分别命名，用于区分日志名称。可以通过Thread.currentThread().setName(name);设置。
首先主函数
import org.apache.logging.log4j.LogManager; import org.apache.logging.log4j.Logger; import org.apache.logging.log4j.ThreadContext; import java.util.concurrent.*; public class TestLog { private static Logger log = LogManager.getLogger(TestLog.class); public static void main(String[] args) { testValidate(); // Thread[] threads = new Thread[10]; // for(int i=0;i<10;i++){ // threads[i] = new TestThread("-"+i); // } // for(Thread thread : threads) { // thread.start(); // } // new Thread(() -> { // log.info("info"); // log.debug("debug"); // log.error("error"); // ThreadContext.remove("ROUTINGKEY"); // }).start(); // new Thread(() -> { // log.info("info"); // log.debug("debug"); // log.error("error"); // ThreadContext.remove("ROUTINGKEY"); // }).start(); } private static void testValidate(){ int threadNum = 3; int totalNum = 3; ConcurrentLinkedDeque<Future> futureList = new ConcurrentLinkedDeque<>(); CountDownLatch begin = new CountDownLatch(1); ExecutorService executor = Executors.newFixedThreadPool(threadNum); for(int i=0;i<totalNum;i++){ Future submit = executor.submit(new TestThread("name"+i)); futureList.add(submit); } begin.countDown(); executor.shutdown(); } }
主函数对TestThread进行调用，在TestThread中完成对于线程的命名。
import org.apache.logging.log4j.LogManager; import org.apache.logging.log4j.Logger; import org.apache.logging.log4j.ThreadContext; import org.apache.logging.log4j.core.appender.FileAppender; import java.util.concurrent.Callable; class TestThread implements Callable { private static Logger log = LogManager.getLogger(TestLog.class); String name; public TestThread(String name) { this.name = name; } // @Override // public void run() { //// ThreadContext.put("ROUTINGKEY", Thread.currentThread().getName()); // try { // System.out.println(Thread.currentThread().getName()); // log.info(Thread.currentThread().getName()); // log.error("error:"+Thread.currentThread().getName()); // Upload upload = new Upload(); // upload.testUpload(Thread.currentThread().getName()); // } catch (Exception e) { // e.printStackTrace(); // } // } @Override public Object call(){ Thread.currentThread().setName(name); Upload upload = new Upload(); upload.testUpload(name); return null; } }
TestThread调用upload方法，进行日志的输出。
import org.apache.logging.log4j.LogManager; import org.apache.logging.log4j.Logger; public class Upload { private static Logger log = LogManager.getLogger(Upload.class); public void testUpload(String name){ log.info("in testUpload" + name); } }
