Spring Boot SLF4j Logback example
摘要: In this tutorial, we will show you how to use Logback in Spring Boot framework.
In this tutorial, we will show you how to use Logback in Spring Boot framework.
Technologies used :
- Spring Boot 2.1.2.RELEASE
- Spring 5.1.4.RELEASE
- Logback 1.2.3
- Maven 3
- Java 8
1. Project Directory
2. Maven
In Spring Boot, Logback is the default logging framework, just add spring-boot-starter-web, it will pull in the logback dependencies.
pom.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>
<artifactId>spring-boot-slf4j</artifactId>
<packaging>jar</packaging>
<name>Spring Boot SLF4j</name>
<version>1.0</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.2.RELEASE</version>
</parent>
<properties>
<java.version>1.8</java.version>
</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-thymeleaf</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<optional>true</optional>
</dependency>
</dependencies>
<build>
<plugins>
<!-- Package as an executable jar/war -->
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.22.0</version>
</plugin>
</plugins>
</build>
</project>
Display the project dependencies.
$ mvn dependency:tree +- org.springframework.boot:spring-boot-starter-web:jar:2.1.2.RELEASE:compile [INFO] | +- org.springframework.boot:spring-boot-starter:jar:2.1.2.RELEASE:compile [INFO] | | +- org.springframework.boot:spring-boot-starter-logging:jar:2.1.2.RELEASE:compile [INFO] | | | +- ch.qos.logback:logback-classic:jar:1.2.3:compile [INFO] | | | | \- ch.qos.logback:logback-core:jar:1.2.3:compile
$ mvn dependency:tree org.springframework.boot:spring-boot-slf4j:jar:1.0 [INFO] +- org.springframework.boot:spring-boot-starter-web:jar:2.1.2.RELEASE:compile [INFO] | +- org.springframework.boot:spring-boot-starter:jar:2.1.2.RELEASE:compile [INFO] | | +- org.springframework.boot:spring-boot-starter-logging:jar:2.1.2.RELEASE:compile [INFO] | | | +- ch.qos.logback:logback-classic:jar:1.2.3:compile [INFO] | | | | \- ch.qos.logback:logback-core:jar:1.2.3:compile [INFO] | | | +- org.apache.logging.log4j:log4j-to-slf4j:jar:2.11.1:compile [INFO] | | | | \- org.apache.logging.log4j:log4j-api:jar:2.11.1:compile [INFO] | | | \- org.slf4j:jul-to-slf4j:jar:1.7.25:compile [INFO] | | +- javax.annotation:javax.annotation-api:jar:1.3.2:compile [INFO] | | +- org.springframework:spring-core:jar:5.1.4.RELEASE:compile [INFO] | | | \- org.springframework:spring-jcl:jar:5.1.4.RELEASE:compile [INFO] | | \- org.yaml:snakeyaml:jar:1.23:runtime [INFO] | +- org.springframework.boot:spring-boot-starter-json:jar:2.1.2.RELEASE:compile [INFO] | | +- com.fasterxml.jackson.core:jackson-databind:jar:2.9.8:compile [INFO] | | | +- com.fasterxml.jackson.core:jackson-annotations:jar:2.9.0:compile [INFO] | | | \- com.fasterxml.jackson.core:jackson-core:jar:2.9.8:compile [INFO] | | +- com.fasterxml.jackson.datatype:jackson-datatype-jdk8:jar:2.9.8:compile [INFO] | | +- com.fasterxml.jackson.datatype:jackson-datatype-jsr310:jar:2.9.8:compile [INFO] | | \- com.fasterxml.jackson.module:jackson-module-parameter-names:jar:2.9.8:compile [INFO] | +- org.springframework.boot:spring-boot-starter-tomcat:jar:2.1.2.RELEASE:compile [INFO] | | +- org.apache.tomcat.embed:tomcat-embed-core:jar:9.0.14:compile [INFO] | | +- org.apache.tomcat.embed:tomcat-embed-el:jar:9.0.14:compile [INFO] | | \- org.apache.tomcat.embed:tomcat-embed-websocket:jar:9.0.14:compile [INFO] | +- org.hibernate.validator:hibernate-validator:jar:6.0.14.Final:compile [INFO] | | +- javax.validation:validation-api:jar:2.0.1.Final:compile [INFO] | | +- org.jboss.logging:jboss-logging:jar:3.3.2.Final:compile [INFO] | | \- com.fasterxml:classmate:jar:1.4.0:compile [INFO] | +- org.springframework:spring-web:jar:5.1.4.RELEASE:compile [INFO] | | \- org.springframework:spring-beans:jar:5.1.4.RELEASE:compile [INFO] | \- org.springframework:spring-webmvc:jar:5.1.4.RELEASE:compile [INFO] | +- org.springframework:spring-aop:jar:5.1.4.RELEASE:compile [INFO] | +- org.springframework:spring-context:jar:5.1.4.RELEASE:compile [INFO] | \- org.springframework:spring-expression:jar:5.1.4.RELEASE:compile [INFO] +- org.springframework.boot:spring-boot-starter-thymeleaf:jar:2.1.2.RELEASE:compile [INFO] | +- org.thymeleaf:thymeleaf-spring5:jar:3.0.11.RELEASE:compile [INFO] | | +- org.thymeleaf:thymeleaf:jar:3.0.11.RELEASE:compile [INFO] | | | +- org.attoparser:attoparser:jar:2.0.5.RELEASE:compile [INFO] | | | \- org.unbescape:unbescape:jar:1.1.6.RELEASE:compile [INFO] | | \- org.slf4j:slf4j-api:jar:1.7.25:compile [INFO] | \- org.thymeleaf.extras:thymeleaf-extras-java8time:jar:3.0.2.RELEASE:compile [INFO] \- org.springframework.boot:spring-boot-devtools:jar:2.1.2.RELEASE:compile (optional) [INFO] +- org.springframework.boot:spring-boot:jar:2.1.2.RELEASE:compile [INFO] \- org.springframework.boot:spring-boot-autoconfigure:jar:2.1.2.RELEASE:compile
3. application.properties
3.1 Configure the logging in application.properties
application.properties
# logging level
logging.level.org.springframework=ERROR
logging.level.com.mkyong=DEBUG
# output to a file
logging.file=app.log
# temp folder example
#logging.file=${java.io.tmpdir}/app.log
logging.pattern.file=%d %p %c{1.} [%t] %m%n
logging.pattern.console=%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n
## if no active profile, default is 'default'
##spring.profiles.active=prod
# root level
#logging.level.=INFO
3.2 This is the equivalent in YAML format.
application.yml
logging:
level:
org.springframework: ERROR
com.mkyong: DEBUG
pattern:
console: "%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"
file: "%d %p %c{1.} [%t] %m%n"
file: app.log
4. logback.xml
The above logging configuration is sufficient for development. For production, we need more logging features like file rolling or SMTP. In Spring Boot, we still allow to configure logback via the standard logback.xml
logback.xml
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<property name="HOME_LOG" value="logs/app.log"/>
<appender name="FILE-ROLLING" class="ch.qos.logback.core.rolling.RollingFileAppender">
<file>${HOME_LOG}</file>
<rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
<fileNamePattern>logs/archived/app.%d{yyyy-MM-dd}.%i.log</fileNamePattern>
<!-- each archived file, size max 10MB -->
<maxFileSize>10MB</maxFileSize>
<!-- total size of all archive files, if total size > 20GB,
it will delete old archived file -->
<totalSizeCap>20GB</totalSizeCap>
<!-- 60 days to keep -->
<maxHistory>60</maxHistory>
</rollingPolicy>
<encoder>
<pattern>%d %p %c{1.} [%t] %m%n</pattern>
</encoder>
</appender>
<logger name="com.mkyong" level="debug" additivity="false">
<appender-ref ref="FILE-ROLLING"/>
</logger>
<root level="error">
<appender-ref ref="FILE-ROLLING"/>
</root>
</configuration>
5. Spring Boot logging by Profile
Note
Read this – Profile-specific configuration
Read this – Profile-specific configuration
To take advantage of the templating features provided by Spring Boot, we can create a logback-spring.xml in the root of the classpath.
In below configuration :
- If no active profile (default), logs to console.
- If the profile is prod, logs to a rolling file.
logback-spring.xml
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<include resource="org/springframework/boot/logging/logback/defaults.xml" />
<springProfile name="default">
<include resource="org/springframework/boot/logging/logback/console-appender.xml"/>
<root level="INFO">
<appender-ref ref="CONSOLE"/>
</root>
</springProfile>
<springProfile name="prod">
<appender name="FILE-ROLLING" class="ch.qos.logback.core.rolling.RollingFileAppender">
<file>app.log</file>
<rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
<fileNamePattern>logs/archived/app.%d{yyyy-MM-dd}.%i.log</fileNamePattern>
<!-- each archived file, size max 10MB -->
<maxFileSize>10MB</maxFileSize>
<!-- total size of all archive files, if total size > 20GB, it will delete old archived file -->
<totalSizeCap>20GB</totalSizeCap>
<!-- 60 days to keep -->
<maxHistory>60</maxHistory>
</rollingPolicy>
<encoder>
<pattern>%d %p %c{1.} [%t] %m%n</pattern>
</encoder>
</appender>
<logger name="org.springframework" level="INFO"/>
<logger name="com.mkyong" level="DEBUG"/>
<root level="ERROR">
<appender-ref ref="FILE-ROLLING"/>
</root>
</springProfile>
</configuration>
Define a spring.profiles.active property to set the current active profile.
application.properties
## if no active profile, default is 'default' spring.profiles.active=prod
6. Hello Logback
6.1 A simple Spring MVC web application, logs something.
HelloController.java
package com.mkyong;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import java.util.Arrays;
import java.util.List;
@Controller
public class HelloController {
private static final Logger logger = LoggerFactory.getLogger(HelloController.class);
@GetMapping("/")
public String hello(Model model) {
List<Integer> data = Arrays.asList(1, 2, 3, 4, 5);
logger.debug("Hello from Logback {}", data);
model.addAttribute("num", data);
return "index"; // index.html
6.2 Template
src/resources/templates/index.html
<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<head>
<title>Spring Boot SLF4j Logback</title>
<link rel="stylesheet" th:href="@{/css/main.css}" href="../../css/main.css"/>
</head>
<body>
<h1>Spring Boot + SLF4j Logback example</h1>
<ul>
<li th:each="n : ${num}" th:text="${n}"></li>
</ul>
</body>
</html>
6.3 CSS
src/resources/static/css/main.css
h1{
color:#0000FF;
7. Demo
7.1 Start Spring Boot
StartWebApplication.java
package com.mkyong;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class StartWebApplication {
public static void main(String[] args) {
SpringApplication.run(StartWebApplication.class, args);
http://localhost:8080
Terminal
15:15:11.588 [http-nio-8080-exec-1] DEBUG com.mkyong.HelloController - Hello from Logback [1, 2, 3, 4, 5]
