Springboot banner

Springboot banner

Banner implementation class as follows:

• SpringBootBanner: Banner default implementation class
• ImageBanner: used to print banner picture log
• ResourceBanner: Resource Banner

Springboot at startup, by default, will print the following information

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.2.5.RELEASE)

Why look at the source code can be analyzed as follows print log

SpringApplication中run方法

public ConfigurableApplicationContext run(String... args) {
            ...
            Banner printedBanner = printBanner(environment);
            ....
        return context;
    }

Call printBanner (ConfigurableEnvironment environment) method

private Banner printBanner(ConfigurableEnvironment environment) {
        if (this.bannerMode == Banner.Mode.OFF) {
            return null;
        }
    //获取资源加载
        ResourceLoader resourceLoader = (this.resourceLoader != null) ? this.resourceLoader
                : new DefaultResourceLoader(getClassLoader());
    //创建SpringApplicationBannerPrinter对象
        SpringApplicationBannerPrinter bannerPrinter = new SpringApplicationBannerPrinter(resourceLoader, this.banner);
        if (this.bannerMode == Mode.LOG) {
            return bannerPrinter.print(environment, this.mainApplicationClass, logger);
        }
    //打印日志
        return bannerPrinter.print(environment, this.mainApplicationClass, System.out);
    }

Banner print(Environment environment, Class<?> sourceClass, PrintStream out) {
        //获取Banner
        Banner banner = getBanner(environment);
        //打印Banner
        banner.printBanner(environment, sourceClass, out);
        return new PrintedBanner(banner, sourceClass);
    }

getBanner(Environment environment)方法

private Banner getBanner(Environment environment) {
    Banners banners = new Banners();
    //添加ImageBanner
    banners.addIfNotNull(getImageBanner(environment));
    //添加TextBanner
    banners.addIfNotNull(getTextBanner(environment));
    if (banners.hasAtLeastOneBanner()) {
        return banners;
    }
    if (this.fallbackBanner != null) {
        return this.fallbackBanner;
    }
    return DEFAULT_BANNER;
}

static final String BANNER_IMAGE_LOCATION_PROPERTY = "spring.banner.image.location";
static final String[] IMAGE_EXTENSION = { "gif", "jpg", "png" };
private Banner getImageBanner(Environment environment) {
        String location = environment.getProperty(BANNER_IMAGE_LOCATION_PROPERTY);
        if (StringUtils.hasLength(location)) {
            Resource resource = this.resourceLoader.getResource(location);
            return resource.exists() ? new ImageBanner(resource) : null;
        }
    //获取banner.gif，banner.jpg,banner.png
        for (String ext : IMAGE_EXTENSION) {
            Resource resource = this.resourceLoader.getResource("banner." + ext);
            if (resource.exists()) {
                return new ImageBanner(resource);
            }
        }
        return null;
    }

    static final String BANNER_LOCATION_PROPERTY = "spring.banner.location";
    static final String DEFAULT_BANNER_LOCATION = "banner.txt";
private Banner getTextBanner(Environment environment) {
    //获取路径下的banner.txt;
        String location = environment.getProperty(BANNER_LOCATION_PROPERTY, DEFAULT_BANNER_LOCATION);
        Resource resource = this.resourceLoader.getResource(location);
        if (resource.exists()) {
            return new ResourceBanner(resource);
        }
        return null;
    }

The code can be understood from the above, if you add banner.txt, banner.jpg file in the classpath below banner.jpg loaded first, then load banner.txt file will be printed later.

Following through to achieve their Banner

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        //SpringApplication.run(Application.class,args);
    
        SpringApplication application=new SpringApplication(Application.class);
        //关闭banner
       // application.setBannerMode(Banner.Mode.OFF);
        application.setBanner(new Mybanner());
        application.run(args);

//        SpringApplicationBuilder applicationBuilder=new SpringApplicationBuilder();
//        //applicationBuilder.profiles("");
//        applicationBuilder.bannerMode(Banner.Mode.OFF).run(args);

    }

}

public class Mybanner implements Banner {

    private static final String BANNER = "Spring Mybanner";
    @Override
    public void printBanner(Environment environment, Class<?> sourceClass, PrintStream out) {
    
        System.out.println(BANNER);
    }

}