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;
Collection exceptionReporters = 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));
}
}到此，关于“springboot-007启动配置的原理是什么”的学习就结束了，希望能够解决大家的疑惑。理论与实践的搭配能更好的帮助大家学习，快去试试吧！若想继续学习更多相关知识，请继续关注创新互联网站，小编会继续努力为大家带来更多实用的文章！
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