查看“Spring Boot 日志配置”的源代码

https://www.bilibili.com/video/BV1iJ411H74S?p=37

=== 示例 无配置文件 默认使用 SLF4J 日志门面 + Logback 日志实现 ===

==== pom.xml ====
<syntaxhighlight lang="xml">
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <artifactId>spring-boot-starter-parent</artifactId>
        <groupId>org.springframework.boot</groupId>
        <version>2.2.2.RELEASE</version>
    </parent>

    <groupId>io.github.jihch</groupId>
    <artifactId>spring-boot-log</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

</project>
</syntaxhighlight>

==== SpringBootLogApplication.java ====
<syntaxhighlight lang="java">
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringBootLogApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringBootLogApplication.class, args);
    }

}
</syntaxhighlight>

==== SpringBootLogApplicationTests.java ====
<syntaxhighlight lang="java">
import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
public class SpringBootLogApplicationTests {

    // 声明日志记录器对象
    public static final Logger LOGGER = LoggerFactory.getLogger(SpringBootLogApplicationTests.class);

    @Test
    public void contextLoads() {
        // 打印日志信息
        LOGGER.error("error");
        LOGGER.warn("warn");
        LOGGER.info("info"); // 默认日志级别
        LOGGER.debug("debug");
        LOGGER.trace("trace");
    }

}
</syntaxhighlight><syntaxhighlight lang="console">
18:07:03.230 [main] DEBUG org.springframework.test.context.BootstrapUtils - Instantiating CacheAwareContextLoaderDelegate from class [org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate]
……

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.2.2.RELEASE)

2023-02-28 18:07:03.751  INFO 47472 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : Starting SpringBootLogApplicationTests on SK-20210414CLPG with PID 47472 (started by Administrator in E:\record\2023\2\27\spring-boot-log)
2023-02-28 18:07:03.752  INFO 47472 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : No active profile set, falling back to default profiles: default
2023-02-28 18:07:04.614  INFO 47472 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2023-02-28 18:07:04.780  INFO 47472 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : Started SpringBootLogApplicationTests in 1.271 seconds (JVM running for 2.006)
2023-02-28 18:07:04.900 ERROR 47472 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : error
2023-02-28 18:07:04.900  WARN 47472 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : warn
2023-02-28 18:07:04.901  INFO 47472 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : info
2023-02-28 18:07:04.911  INFO 47472 --- [extShutdownHook] o.s.s.concurrent.ThreadPoolTaskExecutor  : Shutting down ExecutorService 'applicationTaskExecutor'
</syntaxhighlight>






=== 示例 无配置文件 使用 Log4j 2记录日志也还是会经由桥接器使用 SLF4J 日志门面 + Logback 日志实现 ===

==== SpringBootLogApplicationTests.java ====
<syntaxhighlight lang="java">
import org.apache.logging.log4j.LogManager;
import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
public class SpringBootLogApplicationTests {

    // 声明日志记录器对象
    public static final Logger LOGGER = LoggerFactory.getLogger(SpringBootLogApplicationTests.class);

    @Test
    public void contextLoads() {
        // 打印日志信息
        LOGGER.error("error");
        LOGGER.warn("warn");
        LOGGER.info("info"); // 默认日志级别
        LOGGER.debug("debug");
        LOGGER.trace("trace");

        // 使用 Log4j 2 进行日志记录也还是会通过桥接器切换为 SLF4J 日志门面和 Logback 日志实现
        org.apache.logging.log4j.Logger logger = LogManager.getLogger(SpringBootLogApplicationTests.class);
        logger.info("log4j 2 info");

    }

}
</syntaxhighlight><syntaxhighlight lang="console">
18:19:36.386 [main] DEBUG org.springframework.test.context.BootstrapUtils - Instantiating CacheAwareContextLoaderDelegate from class [org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate]
……

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.2.2.RELEASE)

2023-02-28 18:19:36.807  INFO 14180 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : Starting SpringBootLogApplicationTests on SK-20210414CLPG with PID 14180 (started by Administrator in E:\record\2023\2\27\spring-boot-log)
2023-02-28 18:19:36.808  INFO 14180 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : No active profile set, falling back to default profiles: default
2023-02-28 18:19:37.601  INFO 14180 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2023-02-28 18:19:37.768  INFO 14180 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : Started SpringBootLogApplicationTests in 1.125 seconds (JVM running for 1.82)
2023-02-28 18:19:37.889 ERROR 14180 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : error
2023-02-28 18:19:37.889  WARN 14180 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : warn
2023-02-28 18:19:37.889  INFO 14180 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : info
2023-02-28 18:19:37.890  INFO 14180 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : log4j 2 info
2023-02-28 18:19:37.904  INFO 14180 --- [extShutdownHook] o.s.s.concurrent.ThreadPoolTaskExecutor  : Shutting down ExecutorService 'applicationTaskExecutor'

Process finished with exit code 0

</syntaxhighlight>观察控制台的输出可以发现使用 Log4j 2 的 API 输出和 SLF4J API 输出 pattern 是一样的，因为最终还是经由桥接器调用 SLF4J 作为日志门面 + Logback 作为日志实现进行日志记录




=== 示例 指定自定义 logger 对象日志级别 ===

==== application.properties ====
<syntaxhighlight lang="properties">
# 指定自定义 logger 对象日志级别
logging.level.io.github.jihch=trace
</syntaxhighlight>

==== SpringBootLogApplication.java ====
不变

==== SpringBootLogApplicationTests.java ====
不变<syntaxhighlight lang="console">
18:24:42.138 [main] DEBUG org.springframework.test.context.BootstrapUtils - Instantiating CacheAwareContextLoaderDelegate from class [org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate]
……

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.2.2.RELEASE)

2023-02-28 18:24:42.610  INFO 18868 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : Starting SpringBootLogApplicationTests on SK-20210414CLPG with PID 18868 (started by Administrator in E:\record\2023\2\27\spring-boot-log)
2023-02-28 18:24:42.611 DEBUG 18868 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : Running with Spring Boot v2.2.2.RELEASE, Spring v5.2.2.RELEASE
2023-02-28 18:24:42.611  INFO 18868 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : No active profile set, falling back to default profiles: default
2023-02-28 18:24:43.358  INFO 18868 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2023-02-28 18:24:43.524  INFO 18868 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : Started SpringBootLogApplicationTests in 1.101 seconds (JVM running for 1.879)
2023-02-28 18:24:43.645 ERROR 18868 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : error
2023-02-28 18:24:43.646  WARN 18868 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : warn
2023-02-28 18:24:43.646  INFO 18868 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : info
2023-02-28 18:24:43.646 DEBUG 18868 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : debug
2023-02-28 18:24:43.646 TRACE 18868 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : trace
2023-02-28 18:24:43.647  INFO 18868 --- [           main] i.g.jihch.SpringBootLogApplicationTests  : log4j 2 info
2023-02-28 18:24:43.658  INFO 18868 --- [extShutdownHook] o.s.s.concurrent.ThreadPoolTaskExecutor  : Shutting down ExecutorService 'applicationTaskExecutor'

Process finished with exit code 0

</syntaxhighlight>观察控制台输出，可以看到对比前两次，这次还输出了 debug 和 trace





=== 示例 指定控制台输出日志消息格式 ===

==== application.properties ====
<syntaxhighlight lang="console">
# 指定自定义 logger 对象日志级别
logging.level.io.github.jihch=trace

# 指定控制台输出消息格式
logging.pattern.console=[%-5level] %d{yyyy-MM-dd HH:mm:ss} %c [%thread]===== %msg%n
</syntaxhighlight>其他不变<syntaxhighlight lang="console">
18:38:10.595 [main] DEBUG org.springframework.test.context.BootstrapUtils - Instantiating CacheAwareContextLoaderDelegate from class [org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate]
……

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.2.2.RELEASE)

[INFO ] 2023-02-28 18:38:11 io.github.jihch.SpringBootLogApplicationTests [main]===== Starting SpringBootLogApplicationTests on SK-20210414CLPG with PID 49856 (started by Administrator in E:\record\2023\2\27\spring-boot-log)
[DEBUG] 2023-02-28 18:38:11 io.github.jihch.SpringBootLogApplicationTests [main]===== Running with Spring Boot v2.2.2.RELEASE, Spring v5.2.2.RELEASE
[INFO ] 2023-02-28 18:38:11 io.github.jihch.SpringBootLogApplicationTests [main]===== No active profile set, falling back to default profiles: default
[INFO ] 2023-02-28 18:38:11 org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor [main]===== Initializing ExecutorService 'applicationTaskExecutor'
[INFO ] 2023-02-28 18:38:11 io.github.jihch.SpringBootLogApplicationTests [main]===== Started SpringBootLogApplicationTests in 1.122 seconds (JVM running for 1.803)
[ERROR] 2023-02-28 18:38:12 io.github.jihch.SpringBootLogApplicationTests [main]===== error
[WARN ] 2023-02-28 18:38:12 io.github.jihch.SpringBootLogApplicationTests [main]===== warn
[INFO ] 2023-02-28 18:38:12 io.github.jihch.SpringBootLogApplicationTests [main]===== info
[DEBUG] 2023-02-28 18:38:12 io.github.jihch.SpringBootLogApplicationTests [main]===== debug
[TRACE] 2023-02-28 18:38:12 io.github.jihch.SpringBootLogApplicationTests [main]===== trace
[INFO ] 2023-02-28 18:38:12 io.github.jihch.SpringBootLogApplicationTests [main]===== log4j 2 info
[INFO ] 2023-02-28 18:38:12 org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor [SpringContextShutdownHook]===== Shutting down ExecutorService 'applicationTaskExecutor'

Process finished with exit code 0

</syntaxhighlight>



=== 示例 配置日志输出到文件 ===

==== application.properties ====
<syntaxhighlight lang="properties">
# 指定自定义 logger 对象日志级别
logging.level.io.github.jihch=trace

# 指定控制台输出消息格式
logging.pattern.console=[%-5level] %d{yyyy-MM-dd HH:mm:ss} %c [%thread]===== %msg%n

# 指定存放日志文件的具体路径
logging.file=/logs/springboot.log

# 指定日志文件消息格式
logging.pattern.file=[%-5level] %d{yyyy-MM-dd HH:mm:ss} %c [%thread]===== %msg%n
</syntaxhighlight>目录 E:\logs 下出现 springboot.log 日志文件<syntaxhighlight lang="console">
[INFO ] 2023-02-28 19:11:50 io.github.jihch.SpringBootLogApplicationTests [main]===== Starting SpringBootLogApplicationTests on SK-20210414CLPG with PID 26692 (started by Administrator in E:\record\2023\2\27\spring-boot-log)
[DEBUG] 2023-02-28 19:11:50 io.github.jihch.SpringBootLogApplicationTests [main]===== Running with Spring Boot v2.2.2.RELEASE, Spring v5.2.2.RELEASE
[INFO ] 2023-02-28 19:11:50 io.github.jihch.SpringBootLogApplicationTests [main]===== No active profile set, falling back to default profiles: default
[INFO ] 2023-02-28 19:11:50 org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor [main]===== Initializing ExecutorService 'applicationTaskExecutor'
[INFO ] 2023-02-28 19:11:51 io.github.jihch.SpringBootLogApplicationTests [main]===== Started SpringBootLogApplicationTests in 1.184 seconds (JVM running for 1.867)
[ERROR] 2023-02-28 19:11:51 io.github.jihch.SpringBootLogApplicationTests [main]===== error
[WARN ] 2023-02-28 19:11:51 io.github.jihch.SpringBootLogApplicationTests [main]===== warn
[INFO ] 2023-02-28 19:11:51 io.github.jihch.SpringBootLogApplicationTests [main]===== info
[DEBUG] 2023-02-28 19:11:51 io.github.jihch.SpringBootLogApplicationTests [main]===== debug
[TRACE] 2023-02-28 19:11:51 io.github.jihch.SpringBootLogApplicationTests [main]===== trace
[INFO ] 2023-02-28 19:11:51 io.github.jihch.SpringBootLogApplicationTests [main]===== log4j 2 info
[INFO ] 2023-02-28 19:11:51 org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor [SpringContextShutdownHook]===== Shutting down ExecutorService 'applicationTaskExecutor'
</syntaxhighlight>但其实 logging.file 是已经注解了 @Deprecated 的属性，使用它的替代方案再进行测试<syntaxhighlight lang="properties">
# 指定自定义 logger 对象日志级别
logging.level.io.github.jihch=trace

# 指定控制台输出消息格式
logging.pattern.console=[%-5level] %d{yyyy-MM-dd HH:mm:ss} %c [%thread]===== %msg%n

# 指定存放日志文件的具体路径
# logging.file=/logs/springboot.log #已经被废弃的属性

# 指定日志文件存放的目录，默认的文件名 spring.log
logging.file.path=/logs/springboot/

# 指定日志文件消息格式
logging.pattern.file=[%-5level] %d{yyyy-MM-dd HH:mm:ss} %c [%thread]===== %msg%n
</syntaxhighlight>发现在 E:\logs\springboot\ 目录下出现了 spring.log，内容和之前一样