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springboot情操陶冶-web配置(一)

承接前文springboot情操陶冶-@SpringBootApplication注解解析,在前文讲解的基础上依次看下web方面的相关配置

环境包依赖

pom.xml文件中引入web依赖,炒鸡简单,如下

<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId></dependency>

上述的三行依赖代码便完成了对web环境的配置,此时可以直接运行main()方法

package com.example.demospringbootweb;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplicationpublic class DemoSpringbootWebApplication { public static void main(String[] args) { SpringApplication.run(DemoSpringbootWebApplication.class, args); }}

默认服务是挂载在Tomcat容器中,端口为8080。所以可以通过该链接直接访问http://127.0.0.1:8080便可得到以下页面(未配置index页面的效果)

应用端口和上下文配置

本文将在上文的基础山讲解端口和上下文路径的具体配置以及解析。现附上简单的步骤操作


创建application-servlet.properties文件,专门用于配置应用服务

#server application configserver.port=9001server.servlet.context-path=/demoWeb


application.properties文件中指定激活的profile,用于使上述文件生效

spring.profiles.active=servlet


为了使界面变得稍微友好,引入index.html文件,放置于static目录下,如下


继续运行对应的main()函数,便可访问http://127.0.0.1:9001/demoWeb,得到以下结果

源码剖析

关于Tomcat等容器的配置,springboot采用了EmbeddedWebServerFactoryCustomizerAutoConfigurationServletWebServerFactoryAutoConfiguration两个类便完成了。笔者针对这两个类进行简单的分析

EmbeddedWebServerFactoryCustomizerAutoConfiguration

直接查看其内部源码,如下

@Configuration@EnableConfigurationProperties(ServerProperties.class)public class EmbeddedWebServerFactoryCustomizerAutoConfiguration {}

主要是引入了ServerProperties配置类,而其是读取spring上下文环境中的以server为开头的属性,简单的看下

@ConfigurationProperties(prefix = "server", ignoreUnknownFields = true)public class ServerProperties { @ConditionalOnClass({ Tomcat.class, UpgradeProtocol.class }) public static class TomcatWebServerFactoryCustomizerConfiguration { @Bean public TomcatWebServerFactoryCustomizer tomcatWebServerFactoryCustomizer( Environment environment, ServerProperties serverProperties) { return new TomcatWebServerFactoryCustomizer(environment, serverProperties); } } /** * Nested configuration if Jetty is being used. */ @Configuration @ConditionalOnClass({ Server.class, Loader.class, WebAppContext.class }) public static class JettyWebServerFactoryCustomizerConfiguration { @Bean public JettyWebServerFactoryCustomizer jettyWebServerFactoryCustomizer( Environment environment, ServerProperties serverProperties) { return new JettyWebServerFactoryCustomizer(environment, serverProperties); } } /** * Nested configuration if Undertow is being used. */ @Configuration @ConditionalOnClass({ Undertow.class, SslClientAuthMode.class }) public static class UndertowWebServerFactoryCustomizerConfiguration { @Bean public UndertowWebServerFactoryCustomizer undertowWebServerFactoryCustomizer( Environment environment, ServerProperties serverProperties) { return new UndertowWebServerFactoryCustomizer(environment, serverProperties); } }}

样例中的port/servlet.context-path便是保存在ServerProperties对象中的,具体其内部的属性本文就不展开了,读者可自行去阅读源码。由上述的简单代码得知该自动配置类主要根据classpath环境创建不同的应用容器,默认springboot集成的都是tomcat。我们此处只关注下TomcatWebServerFactoryCustomizer类,下文中会有所提及

ServletWebServerFactoryAutoConfiguration

具体的ServletWebServer容器配置是通过ServletWebServerFactoryAutoConfiguration来创建的,由于代码过长笔者分为几个部分来讲解


头上注解先瞧一发

@Configuration@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)@ConditionalOnClass(ServletRequest.class)@ConditionalOnWebApplication(type = Type.SERVLET)@EnableConfigurationProperties(ServerProperties.class)@Import({ ServletWebServerFactoryAutoConfiguration.BeanPostProcessorsRegistrar.class, ServletWebServerFactoryConfiguration.EmbeddedTomcat.class, ServletWebServerFactoryConfiguration.EmbeddedJetty.class, ServletWebServerFactoryConfiguration.EmbeddedUndertow.class })public class ServletWebServerFactoryAutoConfiguration {}

要想本自动配置生效则必须classpath环境中存在ServletRequest.class等servlet环境依赖类,这一般引入开头的starter-web版块便基本满足了


创建webServerFactory类

@Bean public ServletWebServerFactoryCustomizer servletWebServerFactoryCustomizer( ServerProperties serverProperties) { return new ServletWebServerFactoryCustomizer(serverProperties); } @Bean @ConditionalOnClass(name = "org.apache.catalina.startup.Tomcat") public TomcatServletWebServerFactoryCustomizer tomcatServletWebServerFactoryCustomizer( ServerProperties serverProperties) { return new TomcatServletWebServerFactoryCustomizer(serverProperties); }

这两个bean类和上文中的TomcatWebServerFactoryCustomizer很相似,但仔细阅读源码之后便发现其实这只是tomcat配置的分工处理,小结如下

TomcatWebServerFactoryCustomizer 配置tomcat的主要信息,包含remoteIpValue、connector(最大/最小可接收线程、最大可接收头部大小等等)、uriEncoding、connectionTimeout、maxConnection等属性TomcatServletWebServerFactoryCustomizer 配置tomcat的额外信息,redirectContextRoot(是否在请求根上下文时转发,true则转发路径为/demoWeb/)和useRelativeRedirects(是否使用相对路径)等路径跳转问题处理ServletWebServerFactoryCustomizer 主要配置tomcat的servlet的信息,包含端口、上下文路径、应用名、Session配置、Servlet携带的初始变量等等

通过上述的三个bean类便基本完成了基本的tomcat配置,其都是WebServerFactoryCustomizer接口的实现类,那么是被谁来统一调用以完成上述的配置呢?


1.首先引入了WebServerFactory工厂类,此点可直接看由上述@Import引入的EmbeddedTomcat分析可得

@Configuration @ConditionalOnClass({ Servlet.class, Tomcat.class, UpgradeProtocol.class }) @ConditionalOnMissingBean(value = ServletWebServerFactory.class, search = SearchStrategy.CURRENT) public static class EmbeddedTomcat { @Bean public TomcatServletWebServerFactory tomcatServletWebServerFactory() { return new TomcatServletWebServerFactory(); } }

创建了TomcatServletWebServerFactory的tomcat容器,其余的web容器读者可自行分析


2.最后通过beanPostProcessor接口来完成相应的容器初始化@Import引入的BeanPostProcessorsRegistrar类,注册了webServerFactoryCustomizerBeanPostProcessor类来完成相应的tomcat个性化配置

// 初始化上述的WebServerFactory对象前操作 public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { if (bean instanceof WebServerFactory) { this.postProcessBeforeInitialization((WebServerFactory)bean); } return bean; } // 调用所有实现了WebServerFactoryCustomizer接口的对象 private void postProcessBeforeInitialization(WebServerFactory webServerFactory) { ((Callbacks)LambdaSafe.callbacks(WebServerFactoryCustomizer.class, this.getCustomizers(), webServerFactory, new Object[0]).withLogger(WebServerFactoryCustomizerBeanPostProcessor.class)).invoke((customizer) -> { customizer.customize(webServerFactory); }); } // 查找当前bean工厂中所有类型为WebServerFactoryCustomizer接口对象集合 private Collection<WebServerFactoryCustomizer<?>> getCustomizers() { if (this.customizers == null) { this.customizers = new ArrayList(this.getWebServerFactoryCustomizerBeans()); this.customizers.sort(AnnotationAwareOrderComparator.INSTANCE); this.customizers = Collections.unmodifiableList(this.customizers); } return this.customizers; } private Collection<WebServerFactoryCustomizer<?>> getWebServerFactoryCustomizerBeans() { return this.beanFactory.getBeansOfType(WebServerFactoryCustomizer.class, false, false).values(); }

具体的解析见上述的代码注释,其实也很简单并一目了然,所以如果用户想在tomcat上再作个性化的需求,可自行实现WebServerFactoryCustomizer接口并注册至bean工厂即可

@Configurationpublic MyWebServerFactoryCustomizer implements WebServerFactoryCustomizer<ConfigurableServletWebServerFactory>{ @Override public void customize(ConfigurableServletWebServerFactory factory) { PropertyMapper map = PropertyMapper.get().alwaysApplyingWhenNonNull(); // do personal binding }}

小结

本文只讲述tomcat的相关配置,并举例说明了其port/contextPath的应用配置,更多的配置读者可采用springboot实现的带server前缀的配置以及自行实现WebServerFactoryCustomizer接口去实现

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