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SpringBoot之Banner的使用示例

更新時(shí)間：2017年11月15日 10:30:50 作者：Mr_Qi

本篇文章主要介紹了SpringBoot之Banner的使用示例，小編覺得挺不錯(cuò)的，現(xiàn)在分享給大家，也給大家做個(gè)參考。一起跟隨小編過來看看吧

背景

初次運(yùn)行SpringBoot的小伙伴想必對于SpringBoot打印的Banner很感興趣

Spring Boot在啟動項(xiàng)目時(shí)，控制臺會打印一個(gè)Spring的logo。如果不做任何配置

該信息來源于SpringBootBanner類的靜態(tài)常量BANNER，該屬性是一個(gè)字符串?dāng)?shù)組，不指定任何banner屬性時(shí)，控制臺默認(rèn)輸出該數(shù)組數(shù)據(jù)。我們可以通過Spring Boot提供的強(qiáng)大配置功能來改變banner的輸出。

通常長成這樣

一個(gè)Spring撲面而來~

那么我們能否定制自己的啟動頁呢？

源碼

SpringBoot在啟動時(shí)會調(diào)用如下一段代碼

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長成這樣

/**
 * 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();
 }
 
}

上述代碼可以看到banner存在兩種 imageBanner和textBanner

imageBanner需要配置屬性為banner.image.location

或者支持名為banner格式為 "gif", "jpg", "png的圖片

textBanner支持默認(rèn)情況下在banner.location 或者默認(rèn)為banner.txt

比如我們可以如下設(shè)置

在resource分別放置banner.txt和banner.png

banner.png

banner.txt

/$$$$$$$$ /$$$$$$
| $$_____//$$__ $$
| $$     | $$ \__/
| $$$$$ | $$$$$$$
| $$__/ | $$__ $$
| $$     | $$ \ $$
| $$     | $$$$$$/
|__/      \______/
我們可以看一下結(jié)果