Java Log frame

0 mainstream Java logging framework

Mainstream Java logging framework:

​ 1.JUL - can not be divided into days and files, and is supported to be eliminated

​ 2.log4j - old and mainstream log framework

Log facade frame

3.JCL - only supports JUL and log4j, which is obsolete

4.slf4j - the mainstream log framework in the market

5.logback - the default log implementation framework of springboot

6.log4j2 - log4j is rarely used after logback comes out, so apache launched log4j2, which is very similar to logback in function

Few people have log4j2 now. slf4j facade + log4j2 implementation should be the general trend in the future.

Historical order in which log frames appear:

​ log4j—>JUL---->JCL---->slf4j—>logback---->log4j2

apache (eliminated) (eliminated) log4j founder apache

(few people use it)

1 log4j

1.1 theoretical knowledge

1.1.1 Loggers loggers

Loggers logger ---- controls the output level of logs and whether logs are output

​ logger.fatal(“fatal”); // A serious error, which usually causes the system to crash and terminate the operation

​ logger.error(“error”); // The error message will not affect the system operation

​ logger.warn(“warn”); // Warning messages, problems may occur

​ logger.info(“info”); // Program running information

​ logger.debug(“debug”); // Debugging information is generally used in development,

Record the transfer information of program variable parameters

​ logger.trace(“trace”); // Track information and record all process information of the program

1.1.2 Appenders output

Appenders output - specifies the log output method (output to console, file)

ConsoleAppender outputs logs to the console

FileAppender outputs logs to a file (not meaningful)

Daily rollingfileappender splits and outputs logs to a log file by date,

And each output to a new file

RollingFileAppender splits by size and outputs log information to a log file,

And formulate the size of the document when the file size reaches the specified size

The file name will be changed automatically and a new file will be generated at the same time

The JDBC appender saves the log information to the database

1.1.3 Layout log formatter

Layout log formatter - controls the output format of log information

HTMLLayout html tabular form

SimpleLayout simple log output format info – message

PatternLayout's most powerful formatter typically uses this

General format is:% d{yyyy MM DD HH: mm: SS} [% - 5p]% R% l% m% n

2021-25-12 15:25:23 [INFO ]34  com.tangguanlin.log.Log4jTest.main(Log4jTest.java:20)  info

%p   Output priority and debug,info

%r    Output from application startup to output log The number of milliseconds the message took

%d   The current time of the output server defaults to ISO08601 You can also specify a format, such as:%d{yyyy year MM month dd day HH:mm:ss}
%l   The location where the output log occurs includes the class name, thread, and the number of lines in the code, such as: Test.main(Test.java:10)
     # %l = %c %t %F %L
%c    Output the full name of the class to which the print statement belongs                 
%t    Output the full name of the thread that generated the log
%F   The name of the file where the output log message is generated
%L    Number of lines in output code
%%   Output a"%"character
%m   Output the log information specified in the code
%n   Line feed
%5   Width 5 right justified
%-5  Width 5 left justified

​

1.2 code implementation

1.2.1 maven dependency

<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>

1.2.2 log4j.properties

#Specifies the default configuration information of the RootLogger top-level parent element
#Specify that the log level is = trace, and the appender used is = console console console
#                 trace level console date info level date error level by size
log4j.rootLogger = trace,console,dailyInfoFile,dailyErrorFile,rollingFile

#Specifies the console log output appender object
log4j.appender.console=org.apache.log4j.ConsoleAppender 
#Log output message format: SimpleLayout info--message, of which PatternLayout is most used
log4j.appender.console.layout = org.apache.log4j.PatternLayout
#Content standard format of specified message format:% d{yyyy MM DD HH: mm: SS} [% - 5p]% R% l% m% n
log4j.appender.console.layout.conversionPattern =%d{yyyy-mm-dd HH:mm:ss} [%-5p]%r %l  %m%n

#Do not split, always a log file
#Specifies the file log output appender object
log4j.appender.file=org.apache.log4j.FileAppender 
#Log output message format:
log4j.appender.file.layout = org.apache.log4j.PatternLayout
#Specifies the content of the message format
log4j.appender.file.layout.conversionPattern =%d{yyyy-mm-dd HH:mm:ss} [%-5p]%r %l  %m%n
#Specify the path to save the log file
log4j.appender.file.file= /logs/log4j.log
#Specifies the character set of the log file
log4j.appender.file.encoding = UTF-8

#By date_ info_ split
#Specifies the file log output appender object
log4j.appender.dailyInfoFile=org.apache.log4j.DailyRollingFileAppender 
#Log output message format:
log4j.appender.dailyInfoFile.layout = org.apache.log4j.PatternLayout
#Specifies the content of the message format
log4j.appender.dailyInfoFile.layout.conversionPattern =%d{yyyy-mm-dd HH:mm:ss} [%-5p]%r %l  %m%n
#Specify the path to save the log file
log4j.appender.dailyInfoFile.file= /logs/daily_info.log
#Specifies the character set of the log file
log4j.appender.dailyInfoFile.encoding = UTF-8
#Splitting rules by specified date: 1 copy / day, 1 copy / hour
log4j.appender.dailyInfoFile.datePattern = '.'yyyy-MM-dd HH-mm-ss
#Output info level log to this file
log4j.appender.dailyInfoFile.threshold = info

#By date_ error_ split
#Specifies the file log output appender object
log4j.appender.dailyErrorFile=org.apache.log4j.DailyRollingFileAppender 
#Log output message format:
log4j.appender.dailyErrorFile.layout = org.apache.log4j.PatternLayout
#Specifies the content of the message format
log4j.appender.dailyErrorFile.layout.conversionPattern =%d{yyyy-mm-dd HH:mm:ss} [%-5p]%r %l  %m%n
#Specify the path to save the log file
log4j.appender.dailyErrorFile.file= /logs/daily_error.log
#Specifies the character set of the log file
log4j.appender.dailyErrorFile.encoding = UTF-8
#Splitting rules by specified date: 1 copy / day, 1 copy / hour
log4j.appender.dailyErrorFile.datePattern = '.'yyyy-MM-dd HH-mm-ss
#Output the error level log to this file
log4j.appender.dailyErrorFile.threshold = error

#Split by size
#Specifies the file log output appender object
log4j.appender.rollingFile=org.apache.log4j.RollingFileAppender 
#Log output message format:
log4j.appender.rollingFile.layout = org.apache.log4j.PatternLayout
#Specifies the content of the message format
log4j.appender.rollingFile.layout.conversionPattern =%d{yyyy-mm-dd HH:mm:ss} [%-5p]%r %l  %m%n
#Specify the path to save the log file
log4j.appender.rollingFile.file= /logs/rollingFile.log
#Specifies the character set of the log file
log4j.appender.rollingFile.encoding = UTF-8
#Specifies the size of the log file contents
log4j.appender.rollingFile.maxFileSize = 1MB
#Specifies the number of log files
log4j.appender.rollingFile.maxBackupIndex =10

1.2.3 Log4jTest.java

package com.tangguanlin.log;
import org.apache.log4j.Logger;
/**
 * Note: use of log4j
 * Author: Tang Guanlin
 * Date: 14:00, June 6, 2021
 */
public class Log4jTest {
    public static void main(String[] args) {
      //Get logger object
        Logger logger = Logger.getLogger(Log4jTest.class);
        //Logging output

            //log level
            logger.fatal("fatal"); //A serious error, which usually causes the system to crash and terminate the operation

            logger.error("error"); //The error message will not affect the system operation
            logger.warn("warn"); //Warning messages, problems may occur
            logger.info("info"); //Program running information
            logger.debug("debug"); //Debugging information is generally used in development to record the transfer information of program variables and parameters

            logger.trace("trace"); //Track information and record all process information of the program
    }
}

1.2. 4 operation results

2021-22-17 15:22:27 [FATAL]0 com.tangguanlin.log.Log4jTest.main(Log4jTest.java:16)  fatal
2021-22-17 15:22:27 [ERROR]5 com.tangguanlin.log.Log4jTest.main(Log4jTest.java:18)  error
2021-22-17 15:22:27 [WARN ]5 com.tangguanlin.log.Log4jTest.main(Log4jTest.java:19)  warn
2021-22-17 15:22:27 [INFO ]6 com.tangguanlin.log.Log4jTest.main(Log4jTest.java:20)  info
2021-22-17 15:22:27 [DEBUG]6 com.tangguanlin.log.Log4jTest.main(Log4jTest.java:21)  debug
2021-22-17 15:22:27 [TRACE]6 com.tangguanlin.log.Log4jTest.main(Log4jTest.java:23)  trace

2 slf4j

2.1 theoretical knowledge

slf4j —Simple Logging Facade For Java

JUL - > not divided into days and files - > log4j - > change all the codes for different frameworks

--- > JCL (only support JUL and log4j) was eliminated by the market

slf4j

Log facade and log system

JCL has been eliminated - it only supports JUL and log4j. If the new logging method is used, it needs to reproduce and modify the code, which has been eliminated by the market

slf4j - mainstream log facade Technology

It is mainly to provide a set of standard and standardized API framework for Java log access. Its main significance is to provide interfaces. The specific implementation can be handed over to other log frameworks, such as log4j and logback. Of course, slf4j also provides a relatively simple implementation, but it is rarely used. For general Java projects, the logging framework will choose slf4j API as the facade,

With a specific implementation framework (log4j,logback), a bridge is used in the middle to complete the bridge.

Slf4j is the most popular log facade on the market. In current projects, slf4j is basically used as our log system.

Two functions:

​ 1. Binding of log framework

​ 2. Bridging of log frame

Log binding process using slf4j:

​ 1. Add slf4j API dependencies

​ 2. Use slf4j's API for unified logging in the project

​ 3. Binding specific log implementation framework

​ (1). The binding has implemented slf4j's logging framework, and the corresponding dependencies are added directly

​ (2). Bind the log framework that does not implement slf4j. First add the log adapter, and then add the dependency of the implementation class

​ 4.slf4j has only one log implementation framework binding

(if there are multiple dependencies, the first dependency log implementation is used by default)

Log bridging for slf4j:

​ slf4j-log4j12. The jar adapter is implemented using log4j

​ log4j-over-slf4j. The jar bridge is implemented by the slf4j facade instead of log4j

The adapter and bridge cannot appear at the same time, otherwise it will cause an endless loop.

2.2 slf4j log facade binding code

Specific implementation of slf4j interface facade + log4j

Specific implementation of slf4j interface facade + logback

2.2.1 maven dependency

<!--slf4j-api rely on-->
  <dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-api</artifactId>
    <version>1.7.26</version>
</dependency>

<!--log4j Adapter    slf4j use log4j Adapter required-->
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-log4j12</artifactId>
    <version>1.7.12</version>
</dependency>

<!--log4j rely on-->
<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>

<!--logback rely on-->
<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-classic</artifactId>
    <version>1.2.3</version>
</dependency>

2.2.2 Slf4jTest.java

package com.tangguanlin.log;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
 * Note: use of slf4j 
 *  slf4j Facade + log4j concrete implementation
 *  slf4j Concrete implementation of facade + logback
 * Author: Tang Guanlin
 * Date: 16:00, June 12, 2021
 */
public class Slf4jTest {

    //Generate log object
    public static final Logger LOGGER = LoggerFactory.getLogger(Slf4jTest.class);

    public static void main(String[] args) {

        //Log output
        LOGGER.error("error");
        LOGGER.warn("waring");
        LOGGER.info("info");  //Default level
        LOGGER.debug("debug");
        LOGGER.trace("trace");

        //Output log information using placeholders
        String name ="zhangsan";
        int age = 14;
        LOGGER.info("user:{},{}",name,age);

        try{
            int i = 1/0;
        }catch(Exception e){
            e.printStackTrace();
            LOGGER.warn("Exception occurred:"+e);
        }
    }
}

2.2. 3 operation results

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/D:/01program_soft/01install_before/maven/localRepository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/D:/01program_soft/01install_before/maven/localRepository/org/apache/activemq/activemq-all/5.15.8/activemq-all-5.15.8.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [ch.qos.logback.classic.util.ContextSelectorStaticBinder]
[ERROR] 2021-12-17 15:25:22 com.tangguanlin.log.Slf4jTest main  18 [main] error
[WARN ] 2021-12-17 15:25:22 com.tangguanlin.log.Slf4jTest main  19 [main] waring
[INFO ] 2021-12-17 15:25:22 com.tangguanlin.log.Slf4jTest main  20 [main] info
[DEBUG] 2021-12-17 15:25:22 com.tangguanlin.log.Slf4jTest main  21 [main] debug
[TRACE] 2021-12-17 15:25:22 com.tangguanlin.log.Slf4jTest main  22 [main] trace
[INFO ] 2021-12-17 15:25:22 com.tangguanlin.log.Slf4jTest main  27 [main] user:zhangsan,14
java.lang.ArithmeticException: / by zero
	at com.tangguanlin.log.Slf4jTest.main(Slf4jTest.java:30)
[WARN ] 2021-12-17 15:25:22 com.tangguanlin.log.Slf4jTest main  33 [main] Exception occurred: java.lang.ArithmeticException: / by zero

2.3 slf4j log facade bridging code

Old projects are implemented with log4j

2.3.1 maven dependency

<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>

2.3.2 Log4jOverTest.java

package com.tangguanlin.log;
import org.apache.log4j.Logger;
/**
 * Description: log4j-over-slf4j Use of jar Bridge
 * Author: Tang Guanlin
 * Date: 17:00, June 12, 2021
 */
public class Log4jOverTest {
    public  static  final Logger LOGGER = Logger.getLogger(Log4jOverTest.class);

    public static void main(String[] args) {

        LOGGER.info("log4j info");
        System.out.println(11);
    }
}

2.3. 3 remove log4j dependency

<dependency>

​ <groupId>log4j</groupId>

​ <artifactId>log4j</artifactId>

​ <version>1.2.17</version>

</dependency>

2.3. 4. Add facade frame dependency

<!--slf4j-api-->
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-api</artifactId>
    <version>1.7.26</version>
</dependency>

<!--logback Log implementation-->
<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-classic</artifactId>
    <version>1.2.3</version>
</dependency>

<!--log4j The original old log implementation code of the bridge does not need to be moved--> 
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>log4j-over-slf4j</artifactId>
    <version>1.7.25</version>
</dependency>

2.3.5 Log4jOverTest.java

package com.tangguanlin.log;
import org.apache.log4j.Logger;
/**
 * Description: log4j-over-slf4j Use of jar Bridge
 * Author: Tang Guanlin
 * Date: 17:00, June 12, 2021
 */
public class Log4jOverTest {

    public  static  final Logger LOGGER = Logger.getLogger(Log4jOverTest.class);

    public static void main(String[] args) {

        LOGGER.info("log4j info");
        System.out.println(11);
    }
}

2.3. 6 operation results

2021-28-17 15:28:39 [INFO ]0 com.tangguanlin.log.Log4jOverTest.main(Log4jOverTest.java:14)  log4j info
11

2.4 slf4j log configuration in springboot

To be added

2.5 slf4j log code in springboot

To be added

3 logback

3.1 theoretical knowledge

logback - also designed by the founder of log4j, its performance is better than log4j.

Logback is mainly divided into three modules:

. Logback core: the basic module of the other two modules

. Logback classic: it is an improved version of log4j, and it fully implements the slf4j API

. Logback access: the access module is integrated with the servlet container and provides the function of accessing logs through Http

logback configuration

​ . logback.grocvy

​ . logback-test.xml

​ . logback.xml

If none exists, the default configuration is used

​ 1. Relationship between logback components

​ 1.Logger: the logger of the log. After associating it with the corresponding context of the application, it is used to store the log object,

You can also define log types and levels

​ 2.Appender: used to specify the destination of log output. The destination can be console, file, database, etc

​ 3.Layout: it is responsible for converting time into string and outputting formatted log information.

In logback, the Layout object is encapsulated in the encoder.

Log output format: [%-5level] %d{yyyy-MM-dd HH:mm:ss} %c %M  %L [%thread] %m%n
    %-5level   log level
	%d{yyyy-MM-dd HH:mm:ss}   Date format
	%c    Is the full name of the class
	%M    by method
	%L    Is the line number
	%thread  Is the thread name
	%m perhaps%msg  For information
	%n    Line feed

3.2 use of logback access

The logback access module is integrated with Servlet containers (such as Tomcat and Jetty) to provide HTTP access log function.

We can use the logback access module to replace the access log of tomcat.

​ 1. Set logback access Jar and logback core Jar to $Tomcat_ Under home / lib /

​ 2. Modify $Tomcat_ HOME/conf/server. Add to the Host element in XML:

<Valve className="ch.qos.logback.access.tomcat.LogbackValve" />

​ 3.logback will be in $Tomcat by default_ Find the file logback access under home / conf xml

logback-access.xml configuration file

<?xml version="1.0" encoding="UTF-8"?> 
<configuration> 
    <!-- always a good activate OnConsoleStatusListener --> 
    <statusListener class="ch.qos.logback.core.status.OnConsoleStatusListener"/> 
    <property name="LOG_DIR" value="${catalina.base}/logs"/> 
    <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender"> 
        <file>${LOG_DIR}/access.log</file> 
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy"> 
            <fileNamePattern>access.%d{yyyy-MM-dd}.log.zip</fileNamePattern> 
        </rollingPolicy>
    <encoder> 
        <!-- Format of access log --> 
        <pattern>combined</pattern> 
    </encoder> </appender> 
    <appender-ref ref="FILE"/> 
</configuration>

​ 4. Official configuration: https://logback.qos.ch/access.html#configuration

3.3 code implementation

3.3.1 maven dependency

<!--slf4j Log facade-->
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-api</artifactId>
    <version>1.7.26</version>
</dependency>

<!--logback Log implementation-->
<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-classic</artifactId>
    <version>1.2.3</version>
</dependency>

3.3.2 logback.xml

​ logback.xml configuration file

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
   <!--
       Configure centralized management properties
       We can change the attribute directly value value
       format: ${name}
    -->
    <property name="pattern" value="[%-5level] %d{yyyy-MM-dd HH:mm:ss} %c %M  %L [%thread] %m%n"></property>
    <!--Define log file save path attribute-->
    <property name="log_dir" value="/logs"></property>

    <!--Console log output appender-->
    <appender name="console" class="ch.qos.logback.core.ConsoleAppender">
        <!--Console output stream object default system.out Change to system.err-->
         <target>System.err</target>
       <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
            <pattern>${pattern}</pattern>
       </encoder>
    </appender>

    <!--Log file output appender-->
    <appender name="file" class="ch.qos.logback.core.FileAppender">
        <!--Log file save path-->
        <file>${log_dir}/logbak.log</file>
        <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
            <pattern>${pattern}</pattern>
        </encoder>
    </appender>

    <!--Log splitting and archive compression appender object-->
    <appender name="rollFile" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <!--Log file save path-->
        <file>${log_dir}/roll_logback.log</file>
        <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
            <pattern>${pattern}</pattern>
        </encoder>
        <!--Specify split rules-->
        <rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
            <!--Declare the split file name in time and compression format-->
            <fileNamePattern>${log_dir}/roll_logback.%d{yyyy-MM-dd-HH-mm-ss}.log%i.gz</fileNamePattern>
            <!--Split by file size-->
            <maxFileSize>9012MB</maxFileSize>
        </rollingPolicy>
        <!--Log level filter-->
        <filter class="ch.qos.logback.classic.filter.LevelFilter">
            <!--Log filtering rules-->
            <level>WARN</level>
            <onMatch>ACCEPT</onMatch>
            <onMismatch>DENY</onMismatch>
        </filter>
    </appender>

    <!--Asynchronous log-->
    <appender name="async" class="ch.qos.logback.classic.AsyncAppender">
        <appender-ref ref="rollFile"></appender-ref>
    </appender>

<!--root logger to configure-->
    <root level="All"> <!--log level-->
        <appender-ref ref="console"></appender-ref>
        <appender-ref ref="file"></appender-ref>
        <appender-ref ref="rollFile"></appender-ref>
    </root>
</configuration>     

3.3.3 LogbackTest.java

public static final Logger LOGGER = LoggerFactory.getLogger(LogbackTest.class);

    public static void main(String[] args) {
        for(int i=0;i<10;i++){
            LOGGER.error("erroe");
            LOGGER.warn("wring");
            LOGGER.info("info"); 
            LOGGER.debug("debug");
            LOGGER.trace("trace");
        }
    }
}

3.3. 4 operation results

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/D:/01program_soft/01install_before/maven/localRepository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/D:/01program_soft/01install_before/maven/localRepository/org/apache/activemq/activemq-all/5.15.8/activemq-all-5.15.8.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [ch.qos.logback.classic.util.ContextSelectorStaticBinder]
    
[ERROR] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  17 [main] erroe
[WARN ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  18 [main] wring
[INFO ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  19 [main] info
[DEBUG] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  20 [main] debug
[TRACE] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  21 [main] trace

[ERROR] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  17 [main] erroe
[WARN ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  18 [main] wring
[INFO ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  19 [main] info
[DEBUG] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  20 [main] debug
[TRACE] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  21 [main] trace
    
[ERROR] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  17 [main] erroe
[WARN ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  18 [main] wring
[INFO ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  19 [main] info
[DEBUG] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  20 [main] debug
[TRACE] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  21 [main] trace
    
[ERROR] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  17 [main] erroe
[WARN ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  18 [main] wring
[INFO ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  19 [main] info
[DEBUG] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  20 [main] debug
[TRACE] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  21 [main] trace
    
[ERROR] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  17 [main] erroe
[WARN ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  18 [main] wring
[INFO ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  19 [main] info
[DEBUG] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  20 [main] debug
[TRACE] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  21 [main] trace
    
[ERROR] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  17 [main] erroe
[WARN ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  18 [main] wring
[INFO ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  19 [main] info
[DEBUG] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  20 [main] debug
[TRACE] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  21 [main] trace
    
[ERROR] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  17 [main] erroe
[WARN ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  18 [main] wring
[INFO ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  19 [main] info
[DEBUG] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  20 [main] debug
[TRACE] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  21 [main] trace
    
[ERROR] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  17 [main] erroe
[WARN ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  18 [main] wring
[INFO ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  19 [main] info
[DEBUG] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  20 [main] debug
[TRACE] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  21 [main] trace
    
[ERROR] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  17 [main] erroe
[WARN ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  18 [main] wring
[INFO ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  19 [main] info
[DEBUG] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  20 [main] debug
[TRACE] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  21 [main] trace
    
[ERROR] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  17 [main] erroe
[WARN ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  18 [main] wring
[INFO ] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  19 [main] info
[DEBUG] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  20 [main] debug
[TRACE] 2021-12-17 15:32:19 com.tangguanlin.log.LogbackTest main  21 [main] trace

4 log4j2

4.1 theoretical knowledge

To be added

4.2 implementation code

To be added