springboot-007启动配置的原理是什么
这篇文章主要介绍“springboot-007启动配置的原理是什么”,在日常操作中,相信很多人在springboot-007启动配置的原理是什么问题上存在疑惑,小编查阅了各式资料,整理出简单好用的操作方法,希望对大家解答”springboot-007启动配置的原理是什么”的疑惑有所帮助!接下来,请跟着小编一起来学习吧!
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几个重要的事件回调机制:
ApplicationContextInitializer | 配置在META-INF/spring.factories |
SpringApplicationRunListener | 配置在META-INF/spring.factories |
ApplicationRunner | 只需要放在ioc容器中 |
CommandLineRunner | 只需要放在ioc容器中 |
1. SpringBoot启动流程
创建SpringApplication对象
public SpringApplication(ResourceLoader resourceLoader, Class>... primarySources) { this.resourceLoader = resourceLoader; Assert.notNull(primarySources, "PrimarySources must not be null"); //保存主配置类 this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources)); //判断当前项目是否是一个web应用 this.webApplicationType = WebApplicationType.deduceFromClasspath(); //从类路径下找到META-INF/spring.factories里配置的所有ApplicationContextInitializer,然后保存起来 setInitializers((Collection) getSpringFactoriesInstances( ApplicationContextInitializer.class)); //从类路径下找到META-INF/spring.factories里配置的所有ApplicationListener,然后保存起来 setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class)); //从多个主配置类中找到包含main方法的主配置类 this.mainApplicationClass = deduceMainApplicationClass(); }
运行run方法
/** * Run the Spring application, creating and refreshing a new * {@link ApplicationContext}. * @param args the application arguments (usually passed from a Java main method) * @return a running {@link ApplicationContext} */ public ConfigurableApplicationContext run(String... args) { StopWatch stopWatch = new StopWatch(); stopWatch.start(); ConfigurableApplicationContext context = null; CollectionexceptionReporters = new ArrayList<>(); configureHeadlessProperty(); //从类路径下找到META-INF/spring.factories里配置的所有SpringApplicationRunListener SpringApplicationRunListeners listeners = getRunListeners(args); //回调所有的SpringApplicationRunListener.starting()方法 listeners.starting(); try { //封装命令行参数 ApplicationArguments applicationArguments = new DefaultApplicationArguments( args); //准备环境 // 1. 创建环境完成之后回调所有的SpringApplicationRunListener.environmentPrepared()方法,表示环境已经准备好了 ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments); configureIgnoreBeanInfo(environment); Banner printedBanner = printBanner(environment); //创建ApplicationContext:决定是创建web应用的ioc,还是普通的ioc context = createApplicationContext(); exceptionReporters = getSpringFactoriesInstances( SpringBootExceptionReporter.class, new Class[] { ConfigurableApplicationContext.class }, context); //准备上下文 // 1. 将environment保存到ioc中; // 2. applyInitializers():回调之前保存的所有ApplicationContextInitializer的initialize()方法 // 3. listeners.contextPrepared():回调之前保存的所有SpringApplicationRunListener的contextPrepared()方法 // 4. listeners.contextLoaded():contextPrepared运行完成之后,回调所有SpringApplicationRunListener的contextLoaded()方法 prepareContext(context, environment, listeners, applicationArguments, printedBanner); //刷新容器,即ioc容器的初始化(如果是web应用,还会初始化嵌入式的tomcat) //扫描、创建、加载所有组件的地方 refreshContext(context); afterRefresh(context, applicationArguments); stopWatch.stop(); if (this.logStartupInfo) { new StartupInfoLogger(this.mainApplicationClass) .logStarted(getApplicationLog(), stopWatch); } //回调所有的SpringApplicationRunListener.started()方法 listeners.started(context); //从ioc容器中获取所有的ApplicationRunner和CommandLineRunner,然后进行回调 //所有的ApplicationRunner优先于所有的CommandLineRunner进行回调 callRunners(context, applicationArguments); } catch (Throwable ex) { handleRunFailure(context, ex, exceptionReporters, listeners); throw new IllegalStateException(ex); } try { listeners.running(context); } catch (Throwable ex) { handleRunFailure(context, ex, exceptionReporters, null); throw new IllegalStateException(ex); } //整个SpringBoot应用启动完成以后,返回ioc容器 return context; }
SpringBoot启动流程参考
2. 事件监听机制
配置在META-INF/spring.factories
#SpringApplicationRunListener org.springframework.boot.SpringApplicationRunListener=\ com.qiang.springboot.listener.HelloSpringApplicationRunListener ##ApplicationContextInitializer org.springframework.context.ApplicationContextInitializer=\ com.qiang.springboot.listener.HelloApplicationContextInitializer
ApplicationContextInitializer
public class HelloApplicationContextInitializer implements ApplicationContextInitializer{ @Override public void initialize(ConfigurableApplicationContext configurableApplicationContext) { System.out.println("ApplicationContextInitializer...initialize..." + configurableApplicationContext); } }
SpringApplicationRunListener
public class HelloSpringApplicationRunListener implements SpringApplicationRunListener { public HelloSpringApplicationRunListener(SpringApplication application, String[] args) { } @Override public void starting() { System.out.println("SpringApplicationRunListener...starting..."); } @Override public void environmentPrepared(ConfigurableEnvironment environment) { Object osName = environment.getSystemProperties().get("os.name"); System.out.println("SpringApplicationRunListener...environmentPrepared..." + osName); } @Override public void contextPrepared(ConfigurableApplicationContext context) { System.out.println("SpringApplicationRunListener...contextPrepared..."); } @Override public void contextLoaded(ConfigurableApplicationContext context) { System.out.println("SpringApplicationRunListener...contextLoaded..."); } @Override public void started(ConfigurableApplicationContext context) { System.out.println("SpringApplicationRunListener...started..."); } @Override public void running(ConfigurableApplicationContext context) { System.out.println("SpringApplicationRunListener...running..."); } @Override public void failed(ConfigurableApplicationContext context, Throwable exception) { System.out.println("SpringApplicationRunListener...failed..."); } }
只需要放在ioc容器中
ApplicationRunner
@Component public class HelloApplicationRunner implements ApplicationRunner { @Override public void run(ApplicationArguments args) throws Exception { System.out.println("ApplicationRunner...run..." + args); } }
CommandLineRunner
@Component public class HelloCommandLineRunner implements CommandLineRunner { @Override public void run(String... args) throws Exception { System.out.println("CommandLineRunner...run..." + Arrays.asList(args)); } }
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