视频网站建设教程,网络服务提供者接到权利人,动漫设计师,wordpress没有关键字前言
我们知道开发spring boot项目#xff0c;在启动类上添加注解SpringBootApplication #xff0c;然后引入要自动注入的组件依赖#xff0c;然后现application.properties中加上相应配置就可以自动注入这个组件#xff0c;那么下面看看自动注入组件是如何实现的
一、S…前言
我们知道开发spring boot项目在启动类上添加注解SpringBootApplication 然后引入要自动注入的组件依赖然后现application.properties中加上相应配置就可以自动注入这个组件那么下面看看自动注入组件是如何实现的
一、SpringBootApplication 注解
1、查看SpringBootApplication 类如下
Target({ElementType.TYPE})
Retention(RetentionPolicy.RUNTIME)
Documented
Inherited
SpringBootConfiguration
EnableAutoConfiguration
ComponentScan(excludeFilters {Filter(type FilterType.CUSTOM,classes {TypeExcludeFilter.class}
), Filter(type FilterType.CUSTOM,classes {AutoConfigurationExcludeFilter.class}
)}
)
public interface SpringBootApplication {
}2、查看EnableAutoConfiguration类
Target({ElementType.TYPE})
Retention(RetentionPolicy.RUNTIME)
Documented
Inherited
AutoConfigurationPackage
Import({AutoConfigurationImportSelector.class})
public interface EnableAutoConfiguration {String ENABLED_OVERRIDE_PROPERTY spring.boot.enableautoconfiguration;Class?[] exclude() default {};String[] excludeName() default {};
}这个类又通过Import({AutoConfigurationImportSelector.class}) 导入了 3、AutoConfigurationImportSelector这个bean查看这个bean
public class AutoConfigurationImportSelectorimplements DeferredImportSelector, BeanClassLoaderAware, ResourceLoaderAware,BeanFactoryAware, EnvironmentAware, Ordered {}4、这个AutoConfigurationImportSelector类继承了DeferredImportSelector最终继承了ImportSelector重写这个类的selectImports方法可以快速导入一个bean查看selectImports方法
Overridepublic String[] selectImports(AnnotationMetadata annotationMetadata) {if (!isEnabled(annotationMetadata)) {return NO_IMPORTS;}AutoConfigurationMetadata autoConfigurationMetadata AutoConfigurationMetadataLoader.loadMetadata(this.beanClassLoader);AnnotationAttributes attributes getAttributes(annotationMetadata);ListString configurations getCandidateConfigurations(annotationMetadata,attributes);configurations removeDuplicates(configurations);SetString exclusions getExclusions(annotationMetadata, attributes);checkExcludedClasses(configurations, exclusions);configurations.removeAll(exclusions);configurations filter(configurations, autoConfigurationMetadata);fireAutoConfigurationImportEvents(configurations, exclusions);return StringUtils.toStringArray(configurations);}5、查看ListString configurations getCandidateConfigurations(annotationMetadata, attributes); 这个方法
protected ListString getCandidateConfigurations(AnnotationMetadata metadata,AnnotationAttributes attributes) {ListString configurations SpringFactoriesLoader.loadFactoryNames(getSpringFactoriesLoaderFactoryClass(), getBeanClassLoader());Assert.notEmpty(configurations,No auto configuration classes found in META-INF/spring.factories. If you are using a custom packaging, make sure that file is correct.);return configurations;}6、这个方法最终会调用loadSpringFactories方法这个方法把META-INF/spring.factories定义的类全部读到出来
# Auto Configure
org.springframework.boot.autoconfigure.EnableAutoConfiguration\
org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration,\
org.springframework.boot.autoconfigure.aop.AopAutoConfiguration,\
org.springframework.boot.autoconfigure.amqp.RabbitAutoConfiguration,\
org.springframework.boot.autoconfigure.batch.BatchAutoConfiguration,\private static MapString, ListString loadSpringFactories(Nullable ClassLoader classLoader) {MultiValueMapString, String result (MultiValueMap)cache.get(classLoader);if (result ! null) {return result;} else {try {EnumerationURL urls classLoader ! null ? classLoader.getResources(META-INF/spring.factories) : ClassLoader.getSystemResources(META-INF/spring.factories);LinkedMultiValueMap result new LinkedMultiValueMap();while(urls.hasMoreElements()) {URL url (URL)urls.nextElement();UrlResource resource new UrlResource(url);Properties properties PropertiesLoaderUtils.loadProperties(resource);Iterator var6 properties.entrySet().iterator();while(var6.hasNext()) {Entry?, ? entry (Entry)var6.next();ListString factoryClassNames Arrays.asList(StringUtils.commaDelimitedListToStringArray((String)entry.getValue()));result.addAll((String)entry.getKey(), factoryClassNames);}}cache.put(classLoader, result);return result;} catch (IOException var9) {throw new IllegalArgumentException(Unable to load factories from location [META-INF/spring.factories], var9);}}}7、最终spring会根据这些组件中定义的注入条件将这些组件自动注入org.springframework.boot.autoconfigure下放了所有自动注入的组件以aop这个组件为例
Configuration
//条件注入当有 EnableAspectJAutoProxy.class, Aspect.class, Advice.class,这些class存在时才注入也就是说当引入相关依赖包时注入AnnotatedElement.class
ConditionalOnClass({ EnableAspectJAutoProxy.class, Aspect.class, Advice.class,AnnotatedElement.class })
//当配置文件中有spring.aop 配置时才注入
ConditionalOnProperty(prefix spring.aop, name auto, havingValue true, matchIfMissing true)
public class AopAutoConfiguration {ConfigurationEnableAspectJAutoProxy(proxyTargetClass false)ConditionalOnProperty(prefix spring.aop, name proxy-target-class, havingValue false, matchIfMissing false)public static class JdkDynamicAutoProxyConfiguration {}ConfigurationEnableAspectJAutoProxy(proxyTargetClass true)ConditionalOnProperty(prefix spring.aop, name proxy-target-class, havingValue true, matchIfMissing true)public static class CglibAutoProxyConfiguration {}}二、spring boot内嵌tomcat
最简单的tomcat集成 1、添加pom文件
dependencies!--Java语言操作tomcat --dependencygroupIdorg.apache.tomcat.embed/groupIdartifactIdtomcat-embed-core/artifactIdversion8.5.16/version/dependency!-- tomcat对jsp支持 --dependencygroupIdorg.apache.tomcat/groupIdartifactIdtomcat-jasper/artifactIdversion8.5.16/version/dependency/dependencies2、新建一个servlet文件
public class IndexServlet extends HttpServlet {Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doPost(req, resp);}Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {resp.getWriter().print(this is index... tomcat);}}3、新建一个启动类
public class DTomcat {private static int PORT 8080;private static String CONTEX_PATH /clock;private static String SERVLET_NAME indexServlet;public static void main(String[] args) throws LifecycleException, InterruptedException {// 创建tomcat服务器Tomcat tomcatServer new Tomcat();// 指定端口号tomcatServer.setPort(PORT);// 是否设置自动部署tomcatServer.getHost().setAutoDeploy(false);// 创建上下文StandardContext standardContex new StandardContext();standardContex.setPath(CONTEX_PATH);// 监听上下文standardContex.addLifecycleListener(new Tomcat.FixContextListener());// tomcat容器添加standardContextomcatServer.getHost().addChild(standardContex);// 创建ServlettomcatServer.addServlet(CONTEX_PATH, SERVLET_NAME, new IndexServlet());// servleturl映射standardContex.addServletMappingDecoded(/index, SERVLET_NAME);tomcatServer.start();System.out.println(tomcat服务器启动成功..);// 异步进行接收请求tomcatServer.getServer().await();}
}4、运行main在浏览器输入 http://localhost:8080/clock/index
spring boot内嵌tomcat 1、启动一个spring boot项目查看控制台最下的日志 可以看出spring boot在启动的时候启动一个tomcat实际上它启动的方式也是上面那么启动方式 2、tomcat加载流程 tomcat也是一个组件那么它的引入方式也是通过spring.factories文件注入的 3、查看ServletWebServerFactoryAutoConfiguration这个类 ServletWebServerFactoryAutoConfiguration这个类用import快速导入了EmbeddedTomcat类 4、查看EmbeddedTomcat类 这个类注入了TomcatServletWebServerFactory这个bean
ConfigurationConditionalOnClass({ Servlet.class, Tomcat.class, UpgradeProtocol.class })ConditionalOnMissingBean(value ServletWebServerFactory.class, search SearchStrategy.CURRENT)public static class EmbeddedTomcat {Beanpublic TomcatServletWebServerFactory tomcatServletWebServerFactory() {return new TomcatServletWebServerFactory();}}4、查看TomcatServletWebServerFactory类 这个类有一个getWebServer方法如下 这个方法启动了一个tomcat那么这个方法是在哪个地方调用的可以在这个方法上打上断点查看它的调用链
public WebServer getWebServer(ServletContextInitializer... initializers) {Tomcat tomcat new Tomcat();File baseDir this.baseDirectory ! null ? this.baseDirectory : this.createTempDir(tomcat);tomcat.setBaseDir(baseDir.getAbsolutePath());Connector connector new Connector(this.protocol);tomcat.getService().addConnector(connector);this.customizeConnector(connector);tomcat.setConnector(connector);tomcat.getHost().setAutoDeploy(false);this.configureEngine(tomcat.getEngine());Iterator var5 this.additionalTomcatConnectors.iterator();while(var5.hasNext()) {Connector additionalConnector (Connector)var5.next();tomcat.getService().addConnector(additionalConnector);}this.prepareContext(tomcat.getHost(), initializers);return this.getTomcatWebServer(tomcat);}5、在getWebServer方法打断点然后启动spring boot的main方法查看调用链如下 6、启动流程分析 查看main里面的run方法 这个方法主要new 了一个SpringApplication对象然后执行了run方法
public static ConfigurableApplicationContext run(Class?[] primarySources, String[] args) {return (new SpringApplication(primarySources)).run(args);}SpringApplication结构方法 加载了相关类没有执行
public SpringApplication(ResourceLoader resourceLoader, Class?... primarySources) {this.resourceLoader resourceLoader;Assert.notNull(primarySources, PrimarySources must not be null);//保存主类this.primarySources new LinkedHashSet(Arrays.asList(primarySources));//判断当前是什么类型项目this.webApplicationType WebApplicationType.deduceFromClasspath();//从类路径下找到META-INF/spring.factories配置的所有ApplicationContextInitializersetInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));//从类路径下找到META-INF/spring.factories配置的所有ApplicationListenersetListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));this.mainApplicationClass deduceMainApplicationClass();
}run方法
public ConfigurableApplicationContext run(String... args) {StopWatch stopWatch new StopWatch();stopWatch.start();ConfigurableApplicationContext context null;CollectionSpringBootExceptionReporter exceptionReporters new ArrayList();configureHeadlessProperty();//从类路径下META‐INF/spring.factories取得SpringApplicationRunListenersSpringApplicationRunListeners listeners getRunListeners(args);
//回调所有的获取SpringApplicationRunListener.starting()方法listeners.starting();try {//封装命令行参数ApplicationArguments applicationArguments new DefaultApplicationArguments(args);//准备环境ConfigurableEnvironment environment prepareEnvironment(listeners,applicationArguments);configureIgnoreBeanInfo(environment);//创回调SpringApplicationRunListener.environmentPrepared()
//表示环境准备完成//打印Banner Banner printedBanner printBanner(environment);//根据环境创建contextcontext createApplicationContext();//错误的异常报表exceptionReporters getSpringFactoriesInstances(SpringBootExceptionReporter.class,new Class[] { ConfigurableApplicationContext.class }, context);//准备上下文环境;//将environment保存到ioc中//applyInitializers()调用所有的ApplicationContextInitializer的initialize方法
//调用所有的SpringApplicationRunListener的contextPrepared()prepareContext(context, environment, listeners, applicationArguments,printedBanner);
//SpringApplicationRunListener的contextLoaded
//刷新容器
//扫描创建加载所有组件refreshContext(context);afterRefresh(context, applicationArguments);stopWatch.stop();if (this.logStartupInfo) {new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);}//所有的SpringApplicationRunListener回调started方法listeners.started(context);//获取所有的ApplicationRunner和CommandLineRunner进行调用callRunners(context, applicationArguments);}catch (Throwable ex) {handleRunFailure(context, ex, exceptionReporters, listeners);throw new IllegalStateException(ex);}try {//所有的SpringApplicationRunListener的running()listeners.running(context);}catch (Throwable ex) {handleRunFailure(context, ex, exceptionReporters, null);throw new IllegalStateException(ex);}return context;
}三、spring boot内嵌tomcat修改web容器
从spring boot启动日志看我们知道spring boot内嵌的web容器是tomcat那么如果我们不想用tomcat 也可以换别的web容器 1、修改pom 排除tomcat引入undertow容器
dependenciesdependencygroupIdorg.springframework.boot/groupIdartifactIdspring-boot-starter-web/artifactIdexclusionsexclusiongroupIdorg.springframework.boot/groupIdartifactIdspring-boot-starter-tomcat/artifactId/exclusion/exclusions/dependencydependencygroupIdorg.springframework.boot/groupIdartifactIdspring-boot-starter-undertow/artifactId/dependency/dependencies这个再启动spring boot项目用的就是undertow容器
