SpringBoot启动流程分析之设置系统属性spring.beaninfo.ignore、自定义banner图（五）

参考
目录

文章目录

- - SpringBoot启动流程分析之设置系统属性spring.beaninfo.ignore、自定义banner图（五）
  - - - 1、设置sping.beaninfo.ignore属性
      - 2、Banner图
      - 2.1、输出banner图
      - 3、自定义banner图

org.springframework.boot.SpringApplication#run(java.lang.String…)

public ConfigurableApplicationContext run(String... args) {StopWatch stopWatch = new StopWatch();stopWatch.start();ConfigurableApplicationContext context = null;Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();configureHeadlessProperty();SpringApplicationRunListeners listeners = getRunListeners(args);listeners.starting();try {// 开始分析 //得到系统属性spring.beaninfo.ignore，如果为空设置为trueconfigureIgnoreBeanInfo(environment);Banner printedBanner = printBanner(environment);//其余部分忽略...}catch (Throwable ex) {handleRunFailure(context, ex, exceptionReporters, listeners);throw new IllegalStateException(ex);}return context;}

流程分析

1、设置sping.beaninfo.ignore属性

private void configureIgnoreBeanInfo(ConfigurableEnvironment environment) {            //得到系统属性spring.beaninfo.ignore，如果为空设置为trueif (System.getProperty(CachedIntrospectionResults.IGNORE_BEANINFO_PROPERTY_NAME) == null) {Boolean ignore = environment.getProperty("spring.beaninfo.ignore",Boolean.class, Boolean.TRUE);System.setProperty(CachedIntrospectionResults.IGNORE_BEANINFO_PROPERTY_NAME,ignore.toString());}
}

2、Banner图

private Banner printBanner(ConfigurableEnvironment environment) {//判断banner图输出模式，off为不输出，直接返回空if (this.bannerMode == Banner.Mode.OFF) {return null;}//得到resourceLoaderResourceLoader resourceLoader = (this.resourceLoader != null)? this.resourceLoader : new DefaultResourceLoader(getClassLoader());//实例化一个SpringApplicationBannerPrinterSpringApplicationBannerPrinter bannerPrinter = new SpringApplicationBannerPrinter(resourceLoader, this.banner);//判断banner是否输出到日志文件if (this.bannerMode == Mode.LOG) {return bannerPrinter.print(environment, this.mainApplicationClass, logger);}//最后就是输出到控制台了，参数包括environment，主类，一个打印流System.outreturn bannerPrinter.print(environment, this.mainApplicationClass, System.out);
}

Banner图的打印模式枚举值：

Mode.OFF ：不输出
Mode.CONSOLE：将输出到System.out,即控制台
Mode.log：输出到日志文件
可以通过SpringApplication对象设置打印模式。设置为OFF，即不输出Banner，启动后效果如下。

@SpringBootApplication
public class Application {public static void main(String[] args) {
//		SpringApplication.run(Application.class, args);SpringApplication application = new SpringApplication(Application.class);application.setBannerMode(Mode.OFF);ConfigurableApplicationContext context = application.run(args);context.close();}
}

在这里插入图片描述

2.1、输出banner图

new一个Banners对象，该对象内部有一个Banner对象的集合，下一步就是得到文本或者图片banner，然后添加到list中，不为空则返回该对象。在Banners的printBanner方法中循环调用对应ResourceBanner和ImageBanner的printBanner方法。

public Banner print(Environment environment, Class<?> sourceClass, PrintStream out) {Banner banner = getBanner(environment);//输出banner图banner.printBanner(environment, sourceClass, out);return new PrintedBanner(banner, sourceClass);
}private Banner getBanner(Environment environment) {Banners banners = new Banners();//得到图片banner，如果不为空就添加到List集合中banners.addIfNotNull(getImageBanner(environment));//得到txt文本banner，同样不为空就添加到List集合中banners.addIfNotNull(getTextBanner(environment));//r如果List不为空，直接返回if (banners.hasAtLeastOneBanner()) {return banners;}//如果该banner对象不为空，返回该banner对象if (this.fallbackBanner != null) {return this.fallbackBanner;}//最后就是返回默认banner图，也就是我们看到的springreturn DEFAULT_BANNER;
}

可以看到banner的配置项，默认位置，默认的txt文件名和支持的banner图片类型，图片名字也是banner加上后缀。如果存在txt文档，返回的就是ResourceBanner，存在图片banner返回的就是ImageBanner，如果不存在都是返回空，则使用默认的SpringBootBanner。也就是启动后看见的那个大大的Spring。
在这里插入图片描述

private Banner getBanner(Environment environment) {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) {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;}

最后就是输出banner图了，System.out.println()；
在这里插入图片描述