SpringBoot之Banner的使用示例

2019-11-26 10:55:54

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来源：转载

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背景

初次运行SpringBoot的小伙伴想必对于SpringBoot打印的Banner很感兴趣

Spring Boot在启动项目时，控制台会打印一个Spring的logo。如果不做任何配置

该信息来源于SpringBootBanner类的静态常量BANNER，该属性是一个字符串数组，不指定任何banner属性时，控制台默认输出该数组数据。我们可以通过Spring Boot提供的强大配置功能来改变banner的输出。

通常长成这样

一个Spring扑面而来~

那么我们能否定制自己的启动页呢？

源码

SpringBoot在启动时会调用如下一段代码

private Banner printBanner(ConfigurableEnvironment environment) { if (this.bannerMode == Banner.Mode.OFF) {  return null; } ResourceLoader resourceLoader = this.resourceLoader != null ? this.resourceLoader   : new DefaultResourceLoader(getClassLoader()); SpringApplicationBannerPrinter bannerPrinter = new SpringApplicationBannerPrinter(   resourceLoader, this.banner); if (this.bannerMode == Mode.LOG) {  return bannerPrinter.print(environment, this.mainApplicationClass, logger); } return bannerPrinter.print(environment, this.mainApplicationClass, System.out);}public Banner print(Environment environment, Class<?> sourceClass, PrintStream out) { Banner banner = getBanner(environment, this.fallbackBanner); banner.printBanner(environment, sourceClass, out); return new PrintedBanner(banner, sourceClass);}private Banner getBanner(Environment environment, Banner definedBanner) { Banners banners = new Banners(); banners.addIfNotNull(getImageBanner(environment)); banners.addIfNotNull(getTextBanner(environment)); if (banners.hasAtLeastOneBanner()) {  return banners; } if (this.fallbackBanner != null) {  return this.fallbackBanner; } return DEFAULT_BANNER;}private static final Banner DEFAULT_BANNER = new SpringBootBanner();

而 SpringBootBanner长成这样

/** * Default Banner implementation which writes the 'Spring' banner. * * @author Phillip Webb */class SpringBootBanner implements Banner {  private static final String[] BANNER = { "",   " . ____   _   __ _ _",   " ///// / ___'_ __ _ _(_)_ __ __ _ // // // //",   "( ( )//___ | '_ | '_| | '_ /// _` | // // // //",   " ///// ___)| |_)| | | | | || (_| | ) ) ) )",   " ' |____| .__|_| |_|_| |_//__, | / / / /",   " =========|_|==============|___/=/_/_/_/" };  private static final String SPRING_BOOT = " :: Spring Boot :: ";  private static final int STRAP_LINE_SIZE = 42;  @Override public void printBanner(Environment environment, Class<?> sourceClass,   PrintStream printStream) {  for (String line : BANNER) {   printStream.println(line);  }  String version = SpringBootVersion.getVersion();  version = (version == null ? "" : " (v" + version + ")");  String padding = "";  while (padding.length() < STRAP_LINE_SIZE   - (version.length() + SPRING_BOOT.length())) {   padding += " ";  }   printStream.println(AnsiOutput.toString(AnsiColor.GREEN, SPRING_BOOT,   AnsiColor.DEFAULT, padding, AnsiStyle.FAINT, version));  printStream.println(); } }

上述代码可以看到banner存在两种 imageBanner和textBanner

imageBanner需要配置属性为banner.image.location

或者支持名为banner格式为 "gif", "jpg", "png的图片

textBanner支持默认情况下在banner.location 或者默认为banner.txt

比如我们可以如下设置

在resource分别放置banner.txt和banner.png

banner.png

banner.txt

/$$$$$$$$ /$$$$$$
| $$_____//$$__ $$
| $$     | $$ /__/
| $$$$$ | $$$$$$$
| $$__/ | $$__ $$
| $$     | $$ / $$
| $$     | $$$$$$/
|__/      /______/
我们可以看一下结果