先说一下 banner相关的配置属性
#spring.main.bannerMode=off # 关闭banner打印
#banner.location=coffee.banne # 设置banner文本文件的位置 、相对于src/main/resources
#banner.image.location=11111.jpg #设置图片、打印的时候会乱码
代码中的用法
核心类 org.springframework.bootSpringApplicationBannerPrinter
核心代码
Banner printedBanner = printBanner(environment);
//如果没定义banner.location 会
private static final Banner DEFAULT_BANNER = new SpringBootBanner();
/** * 有时候可能会返回多个banner,如果按照我的想法 我可能会返回一个list * 但是 人家缺返回了一个banners噢 **/
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 Banner getTextBanner(Environment environment) {
//默认加载 banner.txt文件,可以在resources文件夹下新建一个 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;
}
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);
}
for (String ext : IMAGE_EXTENSION) {
Resource resource = this.resourceLoader.getResource("banner." + ext);
if (resource.exists()) {
return new ImageBanner(resource);
}
}
return null;
}
看一下banners的实现,真的很巧妙
private static class Banners implements Banner {
private final List<Banner> banners = new ArrayList<Banner>();
public void addIfNotNull(Banner banner) {
if (banner != null) {
this.banners.add(banner);
}
}
public boolean hasAtLeastOneBanner() {
return !this.banners.isEmpty();
}
@Override
public void printBanner(Environment environment, Class<?> sourceClass,
PrintStream out) {
for (Banner banner : this.banners) {
banner.printBanner(environment, sourceClass, out);
}
}
}