In-depth understanding of Spring Boot’s log management detailed introduction

This article mainly gives you an in-depth introduction to the relevant information of Spring Boot log management. The introduction in the article is very detailed. Friends in need can refer to it. Let’s take a look together.

Preface

Spring Boot uses Commons Logging in all internal logs, but the default configuration also provides support for common logs,
such as: Java Util Logging , Log4J, Log4J2 and Logback. Each Logger can be configured to use the console or file to output log content.

Log output format

2016-08-19 10:22:04.233 INFO 7368 --- [   main] com.juzi.AsyncTest      : Started AsyncTest in 10.084 seconds (JVM running for 12.545)

The output content elements are as follows:

• Time and date—accurate to milliseconds

• Log level — ERROR, WARN, INFO, DEBUG or TRACE

• Process ID

• Delimiter — identifies the start of the actual log

• Thread name — enclosed in square brackets (may truncate console output)

• Logger name - usually use the class name of the source code

• Log content

##Console output

In Spring Boot, ERROR, WARN, and INFO level logs are configured to be output to the console by default.

We can switch to DEBUG level in two ways:

1. Add the –debug flag after running the command, such as:

$ java -jar myapp.jar – debug
## 2. Configure

debug=true

in application.properties. When this property is set to true, the core Logger (including embedded container, hibernate, spring) will output more content, but the logs of your own application will not be output to DEBUG level.

Colorful output

If your terminal supports ANSI, setting colored output will make the log more readable. Supported by setting the

spring.output.ansi.enabled

parameter in application.properties. 1.NEVER: Disable ANSI-colored output (default option)

2.DETECT: Check whether the terminal supports ANSI, if so, use colored output (recommended option)

3.ALWAYS: Always use ANSI-colored format output. If the terminal does not support it, there will be a lot of interference information. It is not recommended to use

file output

Spring Boot's default configuration will only be output to the console and will not be recorded in a file, but we usually need to record it in a file when using it in a production environment.

To increase file output, you need to configure the

logging.file

or logging.path property in application.properties. 1.

logging.file

, set the file, which can be an absolute path or a relative path. For example: logging.file=my.log
2.

logging.path

, set the directory, spring will be created in this directory. log file, and write the log content, such as: logging.path=/var/logThe log file will be truncated when the size is 10Mb, and a new log file will be generated. , the default levels are: ERROR, WARN, INFO *

Level control

In Spring Boot, you only need to configure it in

application.properties

Complete logging level control. Configuration format:

logging.level.*=LEVEL

1.

logging.level

: Log level control prefix, * is the package name or Logger name
2.LEVEL: Options TRACE, DEBUG, INFO, WARN, ERROR, FATAL, OFF

Example:

logging .level.com.juzi=DEBUG com.juzi

All classes under the package are output at DEBUG level

logging.level.root=WARN

The root log is output at WARN level

Custom log configuration

Since the log service is generally initialized before the ApplicationContext is created, it does not have to be controlled through Spring's configuration file.

Therefore, log control and management can still be well supported through system properties and traditional Spring Boot external configuration files.

According to different log systems, you can organize the configuration file name according to the following rules, and it will be loaded correctly:

    1.Logback：logback-spring.xml, logback-spring.groovy, logback.xml, logback.groovy logback日志配置
     2.Log4j：log4j-spring.properties, log4j-spring.xml, log4j.properties, log4j.xml
     3.Log4j2：log4j2-spring.xml, log4j2.xml
     4.JDK (Java Util Logging)：logging.properties

Spring Boot officially recommends using file names with -spring as your Log configuration (such as using logback-spring.xml instead of logback.xml)

Customized output format

In Spring Boot you can pass in

application.properties

Configure the following parameters to control the output format: 1.

logging.pattern.console

: Define the style of output to the console (JDK Logger is not supported)
2.

logging.pattern.file

: Define the style of output to the file (JDK Logger is not supported)

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