SpringApplication.run(主程序类启动)
public static ConfigurableApplicationContext run(Object source, String... args) {
return run(new Object[] { source }, args);
}
public static ConfigurableApplicationContext run(Object[] sources, String[] args) {
return new SpringApplication(sources).run(args);
}
public SpringApplication(Object... sources) {
initialize(sources);
}
1.创建SpringApplication对象
initialize
@SuppressWarnings({ "unchecked", "rawtypes" })
private void initialize(Object[] sources) {
//保存主配置类
if (sources != null && sources.length > 0) {
this.sources.addAll(Arrays.asList(sources));
}
//判断当前是否一个web应用
this.webEnvironment = deduceWebEnvironment();
//从类路径下找到meta‐INF/spring.factories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配置的所有ApplicationListener
setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
//从多个配置类中找到有main方法的主配置类
this.mainApplicationClass = deduceMainApplicationClass();
}
解析：setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));
privateCollection getSpringFactoriesInstances(Class type) { return getSpringFactoriesInstances(type, new Class[] {}); }
privateCollection getSpringFactoriesInstances(Class type, Class[] parameterTypes, Object... args) { ClassLoader classLoader = Thread.currentThread().getContextClassLoader(); // Use names and ensure unique to protect against duplicates Set names = new linkedHashSet ( SpringFactoriesLoader.loadFactoryNames(type, classLoader)); List instances = createSpringFactoriesInstances(type, parameterTypes, classLoader, args, names); AnnotationAwareOrderComparator.sort(instances); return instances; }
SpringFactoriesLoader.loadFactoryNames(type, classLoader));
public static ListloadFactoryNames(Class factoryClass, ClassLoader classLoader) { String factoryClassName = factoryClass.getName(); try { Enumeration urls = (classLoader != null ? classLoader.getResources(FACTORIES_RESOURCE_LOCATION) : ClassLoader.getSystemResources(FACTORIES_RESOURCE_LOCATION)); List result = new ArrayList (); while (urls.hasMoreElements()) { URL url = urls.nextElement(); Properties properties = PropertiesLoaderUtils.loadProperties(new UrlResource(url)); String factoryClassNames = properties.getProperty(factoryClassName); result.addAll(Arrays.asList(StringUtils.commaDelimitedListToStringArray(factoryClassNames))); } return result; } catch (IOException ex) { throw new IllegalArgumentException("Unable to load [" + factoryClass.getName() + "] factories from location [" + FACTORIES_RESOURCE_LOCATION + "]", ex); } }
FACTORIES_RESOURCE_LOCATION
public static final String FACTORIES_RESOURCE_LOCATION = "meta-INF/spring.factories";
-------------------解析完setInitializers-----------------
解析完：setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));
public void setInitializers(
Collection> initializers) {
this.initializers = new ArrayList>();
this.initializers.addAll(initializers);
}
this.initializers
解析完： setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
public void setListeners(Collection> listeners) {
this.listeners = new ArrayList>();
this.listeners.addAll(listeners);
}
this.listeners
解析： this.mainApplicationClass = deduceMainApplicationClass();
private Class deduceMainApplicationClass() {
try {
StackTraceElement[] stackTrace = new RuntimeException().getStackTrace();
for (StackTraceElement stackTraceElement : stackTrace) {
if ("main".equals(stackTraceElement.getMethodName())) {
return Class.forName(stackTraceElement.getClassName());
}
}
}
catch (ClassNotFoundException ex) {
// Swallow and continue
}
return null;
}
2.运行run方法
public static ConfigurableApplicationContext run(Object[] sources, String[] args) {
return new SpringApplication(sources).run(args);
}
new SpringApplication(sources).run(args)
public ConfigurableApplicationContext run(String... args) {
StopWatch stopWatch = new StopWatch();
stopWatch.start();
ConfigurableApplicationContext context = null;
FailureAnalyzers analyzers = null;
configureHeadlessProperty();
//获取SpringApplicationRunListeners；从类路径下meta‐INF/spring.factories
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
//创建环境完成后回调SpringApplicationRunListener.environmentPrepared()表示环境准备完成
ConfigurableEnvironment environment = prepareEnvironment(listeners,
applicationArguments);
//在控制台上打印图标
Banner printedBanner = printBanner(environment);
//创建ApplicationContext；决定创建web的ioc还是普通的ioc
context = createApplicationContext();
//失败信息
analyzers = new FailureAnalyzers(context);
//准备上下文环境;将environment保存到ioc中；而且applyInitializers()；
//applyInitializers()：回调之前保存的所有的ApplicationContextInitializer的initialize方法
//回调所有的SpringApplicationRunListener的contextPrepared()；
//prepareContext运行完成以后回调所有的SpringApplicationRunListener的contextLoaded()；
prepareContext(context, environment, listeners, applicationArguments,
printedBanner);
//刷新容器；ioc容器初始化(bean加载..)（如果是web应用还会创建嵌入式的Tomcat）；
//扫描，创建，加载所有组件的地方；（配置类，组件，自动配置）
refreshContext(context);
//从ioc容器中获取所有的ApplicationRunner和CommandLineRunner进行回调
//ApplicationRunner先回调，CommandLineRunner再回调
afterRefresh(context, applicationArguments);
//所有的SpringApplicationRunListener回调finished方法
listeners.finished(context, null);
stopWatch.stop();
if (this.logStartupInfo) {
new StartupInfoLogger(this.mainApplicationClass)
.logStarted(getApplicationLog(), stopWatch);
}
//整个SpringBoot应用启动完成以后返回启动的ioc容器；
return context;
}
catch (Throwable ex) {
handleRunFailure(context, listeners, analyzers, ex);
throw new IllegalStateException(ex);
}
}
在控制台上打印图标Banner printedBanner = printBanner(environment);如下
. ____ _ __ _ _ /\ / ___'_ __ _ _(_)_ __ __ _ ( ( )___ | '_ | '_| | '_ / _` | \/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |___, | / / / / =========|_|==============|___/=/_/_/_/3.事件监听机制
配置在meta-INF/spring.factories
1.ApplicationContextInitializer
2.SpringApplicationRunListener
只需要放在ioc容器中
3.ApplicationRunner
4.CommandLineRunner
自己创建实现监听，启动效果查看上面运行run方法的启动时机。
HelloApplicationContextInitializer
import org.springframework.context.ApplicationContextInitializer; import org.springframework.context.ConfigurableApplicationContext; public class HelloApplicationContextInitializer implements ApplicationContextInitializer{ @Override public void initialize(ConfigurableApplicationContext applicationContext) { System.out.println("ApplicationContextInitializer...initialize..."+applicationContext); } }
HelloSpringApplicationRunListener
import org.springframework.boot.SpringApplication;
import org.springframework.boot.SpringApplicationRunListener;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.env.ConfigurableEnvironment;
public class HelloSpringApplicationRunListener implements SpringApplicationRunListener {
//必须有的构造器
public HelloSpringApplicationRunListener(SpringApplication application, String[] args){
}
@Override
public void starting() {
System.out.println("SpringApplicationRunListener...starting...");
}
@Override
public void environmentPrepared(ConfigurableEnvironment environment) {
Object o = environment.getSystemProperties().get("os.name");
System.out.println("SpringApplicationRunListener...environmentPrepared.."+o);
}
@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 finished(ConfigurableApplicationContext context, Throwable exception) {
System.out.println("SpringApplicationRunListener...finished...");
}
}
HelloApplicationRunner
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.stereotype.Component;
@Component
public class HelloApplicationRunner implements ApplicationRunner {
@Override
public void run(ApplicationArguments args) throws Exception {
System.out.println("ApplicationRunner...run....");
}
}
HelloCommandLineRunner
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;
import java.util.Arrays;
@Component
public class HelloCommandLineRunner implements CommandLineRunner {
@Override
public void run(String... args) throws Exception {
System.out.println("CommandLineRunner...run..."+ Arrays.asList(args));
}
}
resources-->meta-INF-->spring.factories 仿照别的配置文件配置
org.springframework.context.ApplicationContextInitializer= com.springboot.listener.HelloApplicationContextInitializer org.springframework.boot.SpringApplicationRunListener= com.springboot.listener.HelloSpringApplicationRunListener
启动项目：输出先后顺序
SpringApplicationRunListener...starting... SpringApplicationRunListener...environmentPrepared..Windows 10 . ____ _ __ _ _ /\ / ___'_ __ _ _(_)_ __ __ _ ( ( )___ | '_ | '_| | '_ / _` | \/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |___, | / / / / =========|_|==============|___/=/_/_/_/ ... SpringApplicationRunListener...contextPrepared... ... SpringApplicationRunListener...contextLoaded... ... ApplicationRunner...run.... CommandLineRunner...run...[] SpringApplicationRunListener...finished... ...2.自动配置
Spring Boot启动扫描所有jar包的meta-INF/spring.factories中配置的 EnableAutoConfiguration组件
spring-boot-autoconfigure.jarmeta-INFspring.factories有启动时需要加载的 EnableAutoConfiguration组件配置
配置文件中使用debug=true可以观看到当前启用的自动配置的信息
自动配置会为容器中添加大量组件
Spring Boot在做任何功能都需要从容器中获取这个功能的组件
Spring Boot 总是遵循一个标准；容器中有我们自己配置的组件就用我们配置的，没有就用自动配 置默认注册进来的组件；
参考之前文章Spring Boot入门+深入(二)--六、自动配置原理：Spring Boot入门+深入(二)_杀神lwz的博客-CSDN博客
Spring Boot入门+深入(一)：Spring Boot入门+深入(一)_杀神lwz的博客-CSDN博客
Spring Boot入门+深入(九)：Spring Boot入门+深入(九)-自定义starters_杀神lwz的博客-CSDN博客
