SpringBoot：底层是Spring框架，Spring框架默认是用JCL；‘
SpringBoot选用 SLF4j和logback；
import org.slf4j.Logger;import org.slf4j.LoggerFactory;public class HelloWorld { public static void main(String[] args) { Logger logger = LoggerFactory.getLogger(HelloWorld.class); logger.info("Hello World"); }} 切换日志框架可以按照slf4j的日志适配图，进行相关的切换；
slf4j+log4j的方式；
pom.xml
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> <exclusions> <exclusion> <artifactId>logback-classic</artifactId> <groupId>ch.qos.logback</groupId> </exclusion> <exclusion> <artifactId>log4j-over-slf4j</artifactId> <groupId>org.slf4j</groupId> </exclusion> </exclusions></dependency><dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-log4j12</artifactId></dependency> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.10.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties>//切换为log4j2 <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> <exclusions> <exclusion> <artifactId>spring-boot-starter-logging</artifactId> <groupId>org.springframework.boot</groupId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-log4j2</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build></project> test import org.junit.Test;import org.junit.runner.RunWith;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.boot.test.context.SpringBootTest;import org.springframework.test.context.junit4.SpringRunner;@RunWith(SpringRunner.class)@SpringBootTestpublic class SpringBoot03LoggingApplicationTests { //记录器 Logger logger = LoggerFactory.getLogger(getClass()); @Test public void contextLoads() { //System.out.println(); //日志的级别； //由低到高 trace<debug<info<warn<error //可以调整输出的日志级别；日志就只会在这个级别以以后的高级别生效 logger.trace("这是trace日志..."); logger.debug("这是debug日志..."); //SpringBoot默认给我们使用的是info级别的，没有指定级别的就用SpringBoot默认规定的级别；root级别 logger.info("这是info日志..."); logger.warn("这是warn日志..."); logger.error("这是error日志..."); }} application.properties #logging.path=# 不指定路径在当前项目下生成springboot.log日志# 可以指定完整的路径；#logging.file=G:/springboot.log# 在当前磁盘的根路径下创建spring文件夹和里面的log文件夹；使用?spring.log 作为默认文件logging.path=/spring/log# 在控制台输出的日志的格式logging.pattern.console=%d{yyyy-MM-dd} [%thread] %-5level %logger{50} - %msg%n# 指定文件中日志输出的格式logging.pattern.file=%d{yyyy-MM-dd} === [%thread] === %-5level === %logger{50} ==== %msg%n log4j.properties ### set log levels ###log4j.rootLogger = debug , stdout , D , E### 输出到控制台 ###log4j.appender.stdout = org.apache.log4j.ConsoleAppenderlog4j.appender.stdout.Target = System.outlog4j.appender.stdout.layout = org.apache.log4j.PatternLayoutlog4j.appender.stdout.layout.ConversionPattern = %d{ABSOLUTE} ===== %5p %c{ 1 }:%L - %m%n#### 输出到日志文件 ####log4j.appender.D = org.apache.log4j.DailyRollingFileAppender#log4j.appender.D.File = logs/log.log#log4j.appender.D.Append = true#log4j.appender.D.Threshold = DEBUG ## 输出DEBUG级别以上的日志#log4j.appender.D.layout = org.apache.log4j.PatternLayout#log4j.appender.D.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss} [ %t:%r ] - [ %p ] %m%n##### 保存异常信息到单独文件 ####log4j.appender.D = org.apache.log4j.DailyRollingFileAppender#log4j.appender.D.File = logs/error.log ## 异常日志文件名#log4j.appender.D.Append = true#log4j.appender.D.Threshold = ERROR ## 只输出ERROR级别以上的日志!!!#log4j.appender.D.layout = org.apache.log4j.PatternLayout#log4j.appender.D.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss} [ %t:%r ] - [ %p ] %m%n