网站建设与管理实训,涂料网站建设,选课网站开发,wordpress 自动生成标签创建项目 版本说明这里使用的 SpringBoot 2.0.0.Release
SpringBoot对于SpringMVC的支持 在之前的开发中很多场景下使用的是基于xml配置文件或者是Java配置类的方式来进行SpringMVC的配置。一般来讲#xff0c;初始的步骤如下所示
1、初始化SpringMVC的DispatcherServlet2、…创建项目 版本说明这里使用的 SpringBoot 2.0.0.Release
SpringBoot对于SpringMVC的支持 在之前的开发中很多场景下使用的是基于xml配置文件或者是Java配置类的方式来进行SpringMVC的配置。一般来讲初始的步骤如下所示
1、初始化SpringMVC的DispatcherServlet2、搭建转码过滤器保证客户端请求进行正确的转码3、搭建视图解析器(View Resolver),告诉Spring从什么地方查找视图以及这些视图使用什么语言编写等4、配置静态资源的位置5、配置所支持的地域以及资源bundle6、配置multipart解析器保证文件上传能够正常工作7、将Tomcat或者Jetty包含能够在Web服务器上运行应用8、建立错误页面 当然不止是上面这些工作。如下图所示为SpringMVC核心的处理流程。
核心处理流
功能流图
1.1 分发器和multipart配置 首先在默认的配置文件中加入如下的一行代码,表示已debug模式运行SpringBoot的应用。
debugtrue配置完成之后会看到控制台会打印出debug信息。
DispatcherServletAutoConfiguration matched:- ConditionalOnClass found required class org.springframework.web.servlet.DispatcherServlet (OnClassCondition)- found session scope (OnWebApplicationCondition)DispatcherServletAutoConfiguration.DispatcherServletConfiguration matched:- ConditionalOnClass found required class javax.servlet.ServletRegistration (OnClassCondition)- Default DispatcherServlet did not find dispatcher servlet beans (DispatcherServletAutoConfiguration.DefaultDispatcherServletCondition)DispatcherServletAutoConfiguration.DispatcherServletRegistrationConfiguration matched:- ConditionalOnClass found required class javax.servlet.ServletRegistration (OnClassCondition)- DispatcherServlet Registration did not find servlet registration bean (DispatcherServletAutoConfiguration.DispatcherServletRegistrationCondition)DispatcherServletAutoConfiguration.DispatcherServletRegistrationConfiguration#dispatcherServletRegistration matched:- ConditionalOnBean (names: dispatcherServlet; types: org.springframework.web.servlet.DispatcherServlet; SearchStrategy: all) found bean dispatcherServlet (OnBeanCondition)EmbeddedWebServerFactoryCustomizerAutoConfiguration matched:- ConditionalOnWebApplication (required) found session scope (OnWebApplicationCondition)EmbeddedWebServerFactoryCustomizerAutoConfiguration.TomcatWebServerFactoryCustomizerConfiguration matched:- ConditionalOnClass found required classes org.apache.catalina.startup.Tomcat, org.apache.coyote.UpgradeProtocol (OnClassCondition)ErrorMvcAutoConfiguration matched:- ConditionalOnClass found required classes javax.servlet.Servlet, org.springframework.web.servlet.DispatcherServlet (OnClassCondition)- found session scope (OnWebApplicationCondition)ErrorMvcAutoConfiguration#basicErrorController matched:- ConditionalOnMissingBean (types: org.springframework.boot.web.servlet.error.ErrorController; SearchStrategy: current) did not find any beans (OnBeanCondition)ErrorMvcAutoConfiguration#errorAttributes matched:- ConditionalOnMissingBean (types: org.springframework.boot.web.servlet.error.ErrorAttributes; SearchStrategy: current) did not find any beans (OnBeanCondition)ErrorMvcAutoConfiguration.DefaultErrorViewResolverConfiguration#conventionErrorViewResolver matched:- ConditionalOnBean (types: org.springframework.web.servlet.DispatcherServlet; SearchStrategy: all) found bean dispatcherServlet; ConditionalOnMissingBean (types: org.springframework.boot.autoconfigure.web.servlet.error.DefaultErrorViewResolver; SearchStrategy: all) did not find any beans (OnBeanCondition)ErrorMvcAutoConfiguration.WhitelabelErrorViewConfiguration matched:- ConditionalOnProperty (server.error.whitelabel.enabled) matched (OnPropertyCondition)- ErrorTemplate Missing did not find error template view (ErrorMvcAutoConfiguration.ErrorTemplateMissingCondition)ErrorMvcAutoConfiguration.WhitelabelErrorViewConfiguration#beanNameViewResolver matched:- ConditionalOnMissingBean (types: org.springframework.web.servlet.view.BeanNameViewResolver; SearchStrategy: all) did not find any beans (OnBeanCondition)ErrorMvcAutoConfiguration.WhitelabelErrorViewConfiguration#defaultErrorView matched:- ConditionalOnMissingBean (names: error; SearchStrategy: all) did not find any beans (OnBeanCondition)GenericCacheConfiguration matched:- Cache org.springframework.boot.autoconfigure.cache.GenericCacheConfiguration automatic cache type (CacheCondition)HttpEncodingAutoConfiguration matched:- ConditionalOnClass found required class org.springframework.web.filter.CharacterEncodingFilter (OnClassCondition)- found session scope (OnWebApplicationCondition)- ConditionalOnProperty (spring.http.encoding.enabled) matched (OnPropertyCondition)HttpEncodingAutoConfiguration#characterEncodingFilter matched:- ConditionalOnMissingBean (types: org.springframework.web.filter.CharacterEncodingFilter; SearchStrategy: all) did not find any beans (OnBeanCondition)HttpMessageConvertersAutoConfiguration matched:- ConditionalOnClass found required class org.springframework.http.converter.HttpMessageConverter (OnClassCondition)HttpMessageConvertersAutoConfiguration#messageConverters matched:- ConditionalOnMissingBean (types: org.springframework.boot.autoconfigure.http.HttpMessageConverters; SearchStrategy: all) did not find any beans (OnBeanCondition)HttpMessageConvertersAutoConfiguration.StringHttpMessageConverterConfiguration matched:- ConditionalOnClass found required class org.springframework.http.converter.StringHttpMessageConverter (OnClassCondition)MultipartAutoConfiguration matched:- ConditionalOnClass found required classes javax.servlet.Servlet, org.springframework.web.multipart.support.StandardServletMultipartResolver, javax.servlet.MultipartConfigElement (OnClassCondition)- found session scope (OnWebApplicationCondition)- ConditionalOnProperty (spring.servlet.multipart.enabled) matched (OnPropertyCondition)MultipartAutoConfiguration#multipartConfigElement matched:- ConditionalOnMissingBean (types: javax.servlet.MultipartConfigElement,org.springframework.web.multipart.commons.CommonsMultipartResolver; SearchStrategy: all) did not find any beans (OnBeanCondition)MultipartAutoConfiguration#multipartResolver matched:- ConditionalOnMissingBean (types: org.springframework.web.multipart.MultipartResolver; SearchStrategy: all) did not find any beans (OnBeanCondition) 下面就来分析一下DispatcherServletAutoConfiguration配置类
DispatcherServletAutoConfiguration AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
Configuration
ConditionalOnWebApplication(type Type.SERVLET)
ConditionalOnClass(DispatcherServlet.class)
AutoConfigureAfter(ServletWebServerFactoryAutoConfiguration.class)
EnableConfigurationProperties(ServerProperties.class)
public class DispatcherServletAutoConfiguration {
首先会发现它是一个 Configuration 注解标注的类说明这是一个典型的Spring配置类。在这个配置类上标注了一个注解 EnableConfigurationProperties(ServerProperties.class),这个注解表示使用了SpringBoot自动配置原理对于配置文件与配置类进行了映射在这里看到向这个配置中注入的自动配置类的 ServerProperties 这里就是在配置文件中以server开头的所有配置。例如在配置文件可以进行端口的设置访问路径配置
server.port8080
server.servlet.context-path/hello在它的内部有一个静态内部类DispatcherServletConfiguration这个内部类也是作为一个配置类存在这里需要注意一个注解 Conditional 这个注解表示满足条件之后才会向容器中注入对应的组件。这里会看到如果容器中有 DefaultDispatcherServletCondition 这个类才会进行处理。也就是说在这里需要一个默认的DispatcherServlet才会生效
Configuration
Conditional(DefaultDispatcherServletCondition.class)
ConditionalOnClass(ServletRegistration.class)
EnableConfigurationProperties(WebMvcProperties.class)
protected static class DispatcherServletConfiguration {private final WebMvcProperties webMvcProperties;public DispatcherServletConfiguration(WebMvcProperties webMvcProperties) {this.webMvcProperties webMvcProperties;}Bean(name DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)public DispatcherServlet dispatcherServlet() {DispatcherServlet dispatcherServlet new DispatcherServlet();dispatcherServlet.setDispatchOptionsRequest(this.webMvcProperties.isDispatchOptionsRequest());dispatcherServlet.setDispatchTraceRequest(this.webMvcProperties.isDispatchTraceRequest());dispatcherServlet.setThrowExceptionIfNoHandlerFound(this.webMvcProperties.isThrowExceptionIfNoHandlerFound());return dispatcherServlet;}BeanConditionalOnBean(MultipartResolver.class)ConditionalOnMissingBean(name DispatcherServlet.MULTIPART_RESOLVER_BEAN_NAME)public MultipartResolver multipartResolver(MultipartResolver resolver) {// Detect if the user has created a MultipartResolver but named it incorrectlyreturn resolver;}}第一步首先来看看对于 DefaultDispatcherServletCondition 进行分析
Order(Ordered.LOWEST_PRECEDENCE - 10)
private static class DefaultDispatcherServletCondition extends SpringBootCondition {//继承父类实现获取匹配结果方法/*** 两个参数* 第一个参数ConditionContext 进行操作的上下文* 第二个参数AnnotatedTypeMetadata 注解类型的元数据*/Overridepublic ConditionOutcome getMatchOutcome(ConditionContext context,AnnotatedTypeMetadata metadata) {//定义默认的DispatcherServlet信息 ConditionMessage.Builder message ConditionMessage.forCondition(Default DispatcherServlet);//从配合beanFactory中进行遍历 ConfigurableListableBeanFactory beanFactory context.getBeanFactory();ListString dispatchServletBeans Arrays.asList(beanFactory.getBeanNamesForType(DispatcherServlet.class, false, false));//找到dispatcherServletif (dispatchServletBeans.contains(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)) {return ConditionOutcome.noMatch(message.found(dispatcher servlet bean).items(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME));}if (beanFactory.containsBean(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)) {return ConditionOutcome.noMatch(message.found(non dispatcher servlet bean).items(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME));}if (dispatchServletBeans.isEmpty()) {return ConditionOutcome.match(message.didNotFind(dispatcher servlet beans).atAll());}return ConditionOutcome.match(message.found(dispatcher servlet bean, dispatcher servlet beans).items(Style.QUOTE, dispatchServletBeans).append(and none is named DEFAULT_DISPATCHER_SERVLET_BEAN_NAME));}}我们知道在使用Bean注解的时候如果没有指定name属性默认会以方法名为容器中Bean的ID在上面这类中对容器中的DispatchServlet进行匹配的时候需要满足下面这个Bean的条件。而这个bean的配置正是可以在webMvcProperteis中进行配置的。
Bean(name DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
public DispatcherServlet dispatcherServlet() {DispatcherServlet dispatcherServlet new DispatcherServlet();dispatcherServlet.setDispatchOptionsRequest(this.webMvcProperties.isDispatchOptionsRequest());dispatcherServlet.setDispatchTraceRequest(this.webMvcProperties.isDispatchTraceRequest());dispatcherServlet.setThrowExceptionIfNoHandlerFound(this.webMvcProperties.isThrowExceptionIfNoHandlerFound());return dispatcherServlet;
}在其内部还有另外一个内部类DispatcherServletRegistrationConfiguration
Configuration
Conditional(DispatcherServletRegistrationCondition.class)
ConditionalOnClass(ServletRegistration.class)
EnableConfigurationProperties(WebMvcProperties.class)
Import(DispatcherServletConfiguration.class)
protected static class DispatcherServletRegistrationConfiguration {private final WebMvcProperties webMvcProperties;private final MultipartConfigElement multipartConfig;public DispatcherServletRegistrationConfiguration(WebMvcProperties webMvcProperties,ObjectProviderMultipartConfigElement multipartConfigProvider) {this.webMvcProperties webMvcProperties;this.multipartConfig multipartConfigProvider.getIfAvailable();}Bean(name DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME)ConditionalOnBean(value DispatcherServlet.class, name DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)public DispatcherServletRegistrationBean dispatcherServletRegistration(DispatcherServlet dispatcherServlet) {DispatcherServletRegistrationBean registration new DispatcherServletRegistrationBean(dispatcherServlet,this.webMvcProperties.getServlet().getPath());registration.setName(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);registration.setLoadOnStartup(this.webMvcProperties.getServlet().getLoadOnStartup());if (this.multipartConfig ! null) {registration.setMultipartConfig(this.multipartConfig);}return registration;}}Order(Ordered.LOWEST_PRECEDENCE - 10)private static class DefaultDispatcherServletCondition extends SpringBootCondition {Overridepublic ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {ConditionMessage.Builder message ConditionMessage.forCondition(Default DispatcherServlet);ConfigurableListableBeanFactory beanFactory context.getBeanFactory();ListString dispatchServletBeans Arrays.asList(beanFactory.getBeanNamesForType(DispatcherServlet.class, false, false));if (dispatchServletBeans.contains(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)) {return ConditionOutcome.noMatch(message.found(dispatcher servlet bean).items(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME));}if (beanFactory.containsBean(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)) {return ConditionOutcome.noMatch(message.found(non dispatcher servlet bean).items(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME));}if (dispatchServletBeans.isEmpty()) {return ConditionOutcome.match(message.didNotFind(dispatcher servlet beans).atAll());}return ConditionOutcome.match(message.found(dispatcher servlet bean, dispatcher servlet beans).items(Style.QUOTE, dispatchServletBeans).append(and none is named DEFAULT_DISPATCHER_SERVLET_BEAN_NAME));}}Order(Ordered.LOWEST_PRECEDENCE - 10)private static class DispatcherServletRegistrationCondition extends SpringBootCondition {Overridepublic ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {ConfigurableListableBeanFactory beanFactory context.getBeanFactory();ConditionOutcome outcome checkDefaultDispatcherName(beanFactory);if (!outcome.isMatch()) {return outcome;}return checkServletRegistration(beanFactory);}private ConditionOutcome checkDefaultDispatcherName(ConfigurableListableBeanFactory beanFactory) {ListString servlets Arrays.asList(beanFactory.getBeanNamesForType(DispatcherServlet.class, false, false));boolean containsDispatcherBean beanFactory.containsBean(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);if (containsDispatcherBean !servlets.contains(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)) {return ConditionOutcome.noMatch(startMessage().found(non dispatcher servlet).items(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME));}return ConditionOutcome.match();}private ConditionOutcome checkServletRegistration(ConfigurableListableBeanFactory beanFactory) {ConditionMessage.Builder message startMessage();ListString registrations Arrays.asList(beanFactory.getBeanNamesForType(ServletRegistrationBean.class, false, false));boolean containsDispatcherRegistrationBean beanFactory.containsBean(DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME);if (registrations.isEmpty()) {if (containsDispatcherRegistrationBean) {return ConditionOutcome.noMatch(message.found(non servlet registration bean).items(DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME));}return ConditionOutcome.match(message.didNotFind(servlet registration bean).atAll());}if (registrations.contains(DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME)) {return ConditionOutcome.noMatch(message.found(servlet registration bean).items(DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME));}if (containsDispatcherRegistrationBean) {return ConditionOutcome.noMatch(message.found(non servlet registration bean).items(DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME));}return ConditionOutcome.match(message.found(servlet registration beans).items(Style.QUOTE, registrations).append(and none is named DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME));}private ConditionMessage.Builder startMessage() {return ConditionMessage.forCondition(DispatcherServlet Registration);}}在Spring中往往会通过 Order 注解来声明优先级可以看到上面的内容对于两个静态内部类都做了是优先级的配置。在其中还有一个比较重要的注解值得关注 AutoConfigureAfter(ServletWebServerFactoryAutoConfiguration.class) 对于这些注解来说都是为了进一步的优化配置顺序细节处理。
