java - SpringApplication.run 后不打印 Logback

Question

在 SpringApplication.run 之后，Logback 不打印但 System.out.println 打印。我正在尝试打印出在上下文中加载的 bean。当然，我可以使用 System.out 做到这一点。但我想用日志来做到这一点。谁能解释我在下面的代码中缺少什么？

import java.util.Arrays;    

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;    

@SpringBootApplication
public class MyApplication {    

  final static Logger logger = LoggerFactory.getLogger(MyApplication.class);    

  public static void main(String[] args) {    

    // This works fine. I am using logback behind the slf4j api. 
    logger.debug("Hello world from Spring Boot.");    

    ApplicationContext appContext = SpringApplication.run(
        MyApplication.class, args);   

    // The system.out works all right. The debug does not. Why?
    logger.debug("Let's inspect the beans provided by Spring Boot:");
    System.out.println("Let's inspect the beans provided by Spring Boot:");   

    String[] beanNames = appContext.getBeanDefinitionNames();
    Arrays.sort(beanNames);
    for (String beanName : beanNames) {
      System.out.println(beanName);
    }
  }
}

/pom.xml

<groupId>fun.and.games</groupId>
<artifactId>learnspringboot</artifactId>
<version>0.1.0</version>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.4.1.RELEASE</version>
</parent>

<dependencies>

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

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

</dependencies>

<build>
    <plugins>

        <!-- mvn -e clean install exec:java -->
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>exec-maven-plugin</artifactId>
            <configuration>
                <mainClass>fun.and.games.MyApplication</mainClass>
            </configuration>
        </plugin>

        <!-- Configure the project to use java 8 version. -->
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
                <!-- Disable annotation processing for ourselves. -->
                <compilerArgument>-proc:none</compilerArgument>
            </configuration>
        </plugin>

        <!-- mvn -e clean install spring-boot:run -->
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

src/main/resources/application.properties

logging.level.root=DEBUG

Answer 1

你不需要在 pom.xml 中添加 Logback 依赖，因为 spring boot 提供了 SLF4J 和 Logback 依赖。 Spring Boot 在配置文件中为 Logback 提供了一个默认配置，在你的应用程序中可以默认打印 INFO 消息。如果您想在日志中获取 DEBUG 消息，则必须在 application.properties 文件中进行配置。在属性文件中添加 logging.level.your package=DEBUG。例如你的包是“com.my.app”然后使用

logging.level.com.my.app=DEBUG

并且Spring web DEBUG日志可以像这样启用

logging.level.org.springframework.web=DEBUG

请在 http://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-logging.html 查看日志记录级别的详细信息