SpringMVC的Demo与@EnableWebMvc注解

1. demo ׼

Ϊ˸õط springmvc Դ룬Ҫ׼һ springmvc demo demo Ƿ spring-learn ģ顣

1. tomcat

tomcat 8 ֮tomcat ṩ˶аҪʱֱͿˣӦ gradle :

optional("org.apache.tomcat.embed:tomcat-embed-core")

spring Ŀ build.gradle УѾ tomcat-embed-core-9.0.29.jar spring-learn ģʱָ汾

2. ׼

package org.springframework.learn.mvc.demo01;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;

@Component
@ComponentScan("org.springframework.learn.mvc.demo01")
@EnableWebMvc
public class MvcConfig {

}

Ϊ MvcConfigָĿİɨ·Լͨ @EnableWebMvc mvc ܡ

3. ʵ WebApplicationInitializer

package org.springframework.learn.mvc.demo01;

import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletRegistration;

public class MyWebApplicationInitializer implements WebApplicationInitializer {

    @Override
    public void onStartup(ServletContext servletContext) {
        AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
        context.register(MvcConfig.class);

        DispatcherServlet servlet = new DispatcherServlet(context);
        ServletRegistration.Dynamic registration = servletContext.addServlet("app", servlet);
        registration.setLoadOnStartup(1);
        registration.addMapping("/*");
    }
}

spring ṩһӿ WebApplicationInitializerʵָýӿʱ onStartup(...) д spring applicationContextȻ servelet ע DispatcherServlet

4. ׼ controller

package org.springframework.learn.mvc.demo01;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/test")
public class TestController {

    @RequestMapping("/hello")
    public String hello() {
         System.out.println("hello!!!");
         return "hello world!";
    }
}

׼һ򵥵 controllerһַ "hello world".

5.

ˣ

package org.springframework.learn.mvc.demo01;

import org.apache.catalina.Context;
import org.apache.catalina.LifecycleListener;
import org.apache.catalina.connector.Connector;
import org.apache.catalina.startup.Tomcat;

public class MvcDemo01Main {

    public static void main(String[] args) throws Exception {
        Tomcat tomcat = new Tomcat();

        Connector connector = new Connector();
        connector.setPort(8080);
        connector.setURIEncoding("UTF-8");
        tomcat.getService().addConnector(connector);

        Context context = tomcat.addContext("", System.getProperty("java.io.tmpdir"));
        LifecycleListener lifecycleListener = (LifecycleListener) 
                Class.forName(tomcat.getHost().getConfigClass())
                .getDeclaredConstructor().newInstance();
        context.addLifecycleListener(lifecycleListener);
        tomcat.start();
        tomcat.getServer().await();
    }
}

main УҪ tomcat ߼

У£

̨

ҳ淵أ

Կһ򵥵 springmvc Ŀʹˡ

2. servlet 3.0 淶

¹ϵ springmvc Ŀһ⼸ xml ļ

• web.xmlservlet ļ web ʱIJԼ servlet/listener/filter;
• spring.xmlspring ļҪ spring bean.
• spring-mvc.xmlspringmvc ļ mvc ص beanļϴص beanͼ beancontroller ·ȡ

Ŀʱȼ web.xml web.xml м spring ã spring

demo УǷֲ ûЩã web.xml ļûУô web Ŀôأ

servlet 3.0 ֮ṩһ spi 淶spring ʵ£

1. spring-web ģ /src/main/resources/META-INF/services/ ļ£ļ javax.servlet.ServletContainerInitializer

org.springframework.web.SpringServletContainerInitializer

1. org.springframework.web.SpringServletContainerInitializer ʵ servlet 淶

// @HandlesTypes עservlet淶ʾ webAppInitializerClass Ϊ WebApplicationInitializer.class
@HandlesTypes(WebApplicationInitializer.class)
public class SpringServletContainerInitializer implements ServletContainerInitializer {

    /*
     * д ServletContainerInitializer  onStartup 
     * Ҫʵ spring ṩ WebApplicationInitializer.classȻִ onStartup 
     *
     * Set<Class<?>> webAppInitializerClasses еΪ WebApplicationInitializer.class
     *  @HandlesTypes עָ
     */
    @Override
    public void onStartup(@Nullable Set<Class<?>> webAppInitializerClasses, ServletContext servletContext)
            throws ServletException {

        List<WebApplicationInitializer> initializers = new LinkedList<>();

        if (webAppInitializerClasses != null) {
            for (Class<?> waiClass : webAppInitializerClasses) {
                if (!waiClass.isInterface() && !Modifier.isAbstract(waiClass.getModifiers()) &&
                        WebApplicationInitializer.class.isAssignableFrom(waiClass)) {
                    try {
                       // ʹ÷ʵ WebApplicationInitializer ʵ࣬ӵ initializers 
                        initializers.add((WebApplicationInitializer)
                                ReflectionUtils.accessibleConstructor(waiClass).newInstance());
                    }
                    catch (Throwable ex) {
                        ...
                    }
                }
            }
        }

        servletContext.log(initializers.size() + " ...");
        // ʵOrderdӿڣע @Order ע⣬ʵ PriorityOrderd ӿ
        AnnotationAwareOrderComparator.sort(initializers);
        for (WebApplicationInitializer initializer : initializers) {
           //  WebApplicationInitializer ʵonStartup
           initializer.onStartup(servletContext);
        }
    }

}

1. WebApplicationInitializer ʵ demo ж WebApplicationInitializer ʵ֣

package org.springframework.learn.mvc.demo01;

import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletRegistration;

public class MyWebApplicationInitializer implements WebApplicationInitializer {

    /*
     *  spring Ŀ
     */
    @Override
    public void onStartup(ServletContext servletContext) {
        //  spring  ApplicationContext
        AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
        context.register(MvcConfig.class);

        //  DispatcherServlet  servlet 
        DispatcherServlet servlet = new DispatcherServlet(context);
        ServletRegistration.Dynamic registration = servletContext.addServlet("app", servlet);
        registration.setLoadOnStartup(1);
        registration.addMapping("/*");
    }
}

ִй£

ɴˣspring ˡ

3. @EnableWebMvc

demo Уͨ @EnableWebMvc mvc ܣôעʲôأǽ EnableWebMvc ࣺ

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Import(DelegatingWebMvcConfiguration.class)
public @interface EnableWebMvc {
}

Կעͨ @Import ע DelegatingWebMvcConfiguration.class DelegatingWebMvcConfiguration:

@Configuration(proxyBeanMethods = false)
public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
    ...

}

@Configuration ע⣬Ǹ̳࣬е WebMvcConfigurationSupport``WebMvcConfigurationSupport Ϊ "mvc ֧"ô mvc صõġ

Ϊ˸õطȽܼࣺ

1. DelegatingWebMvcConfiguration @EnableWebMvc ࣬ WebMvcConfigurationSupport ࣬д WebMvcConfigurationSupport ṩ÷

   Copy

   /*
    * @ConfigurationǸ
    * extends WebMvcConfigurationSupport̳WebMvcConfigurationSupport
    */
   @Configuration(proxyBeanMethods = false)
   public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
   
       // WebMvcConfigurerComposite  WebMvcConfigurer ϣᵽ
       private final WebMvcConfigurerComposite configurers = new WebMvcConfigurerComposite();
   
       /**
        * configurers
        * @Autowiredע⣬ʾspringеWebMvcConfigurer bean Ϊ
        * configurersֵ Ȼø÷
        */
       @Autowired(required = false)
       public void setConfigurers(List<WebMvcConfigurer> configurers) {
           if (!CollectionUtils.isEmpty(configurers)) {
               this.configurers.addWebMvcConfigurers(configurers);
           }
       }
   
       /**
        * PathMatch
        */
       @Override
       protected void configurePathMatch(PathMatchConfigurer configurer) {
           //  WebMvcConfigurerComposite ķ
           this.configurers.configurePathMatch(configurer);
       }
   
       // ÷Ҳǵ WebMvcConfigurerComposite Ӧķõ
       ...
   
   }
   
   

2. WebMvcConfigurerComposite``WebMvcConfigurer ϣ

   Copy

   /**
    * ʵ WebMvcConfigurer
    */
   class WebMvcConfigurerComposite implements WebMvcConfigurer {
   
       // delegatesΪ WebMvcConfigurer ļ
       private final List<WebMvcConfigurer> delegates = new ArrayList<>();
   
       /*
        * DelegatingWebMvcConfiguration#setConfigurers
        * ǰѴconfigurersӵdelegates(ҲWebMvcConfigurer)
        */
       public void addWebMvcConfigurers(List<WebMvcConfigurer> configurers) {
           if (!CollectionUtils.isEmpty(configurers)) {
               this.delegates.addAll(configurers);
           }
       }
   
       /**
        * ʱdelegates(ҲWebMvcConfigurer)õ
        * еÿһWebMvcConfigurer
        */
       @Override
       public void configurePathMatch(PathMatchConfigurer configurer) {
           for (WebMvcConfigurer delegate : this.delegates) {
               delegate.configurePathMatch(configurer);
           }
       }
   
       // ƣʡ
       ...
   }
   
   

3. WebMvcConfigurerspringmvc ýӿڣṩ˷dz

   Copy

   public interface WebMvcConfigurer {
   
       default void configurePathMatch(PathMatchConfigurer configurer) {
       }
   
       default void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
       }
   
       default void configureAsyncSupport(AsyncSupportConfigurer configurer) {
       }
   
       ...
   }
   
   

4. WebMvcConfigurationSupportspringmvc ֧

   Copy

   /**
    * ʵawareӿ
    */
   public class WebMvcConfigurationSupport implements ApplicationContextAware, ServletContextAware {
   
       //=================  XxxAware ӿڵķ =================
       @Override
       public void setApplicationContext(@Nullable ApplicationContext applicationContext) {
           this.applicationContext = applicationContext;
       }
   
       @Override
       public void setServletContext(@Nullable ServletContext servletContext) {
           this.servletContext = servletContext;
       }
   
       //================= @Bean spring bean =================
       @Bean
       public RequestMappingHandlerMapping requestMappingHandlerMapping(...) {
           RequestMappingHandlerMapping mapping = createRequestMappingHandlerMapping();
           mapping.setOrder(0);
           // getInterceptors(...) ȡ interceptors¿
           mapping.setInterceptors(getInterceptors(conversionService, resourceUrlProvider));
           mapping.setContentNegotiationManager(contentNegotiationManager);
           // getCorsConfigurations(...) ȡCorsã¿
           mapping.setCorsConfigurations(getCorsConfigurations());
           // getPathMatchConfigurer(...) ȡPathMatchã¿
           PathMatchConfigurer configurer = getPathMatchConfigurer();
   
           ...
   
           return mapping;
       }
       ...
       //================= get xxx ÷springṩĬãԶ =======
       // ȡ interceptors
       protected final Object[] getInterceptors(
               FormattingConversionService mvcConversionService,
               ResourceUrlProvider mvcResourceUrlProvider) {
           if (this.interceptors == null) {
               InterceptorRegistry registry = new InterceptorRegistry();
               // ÷ interceptor¿
               addInterceptors(registry);
               registry.addInterceptor(new ConversionServiceExposingInterceptor(mvcConversionService));
               registry.addInterceptor(new ResourceUrlProviderExposingInterceptor(mvcResourceUrlProvider));
               this.interceptors = registry.getInterceptors();
           }
           return this.interceptors.toArray();
       }
   
       // ȡCors
       protected final Map<String, CorsConfiguration> getCorsConfigurations() {
           if (this.corsConfigurations == null) {
               CorsRegistry registry = new CorsRegistry();
               // ÷ CorsMapping¿
               addCorsMappings(registry);
               this.corsConfigurations = registry.getCorsConfigurations();
           }
           return this.corsConfigurations;
       }
   
       // ȡPathMatch
       protected PathMatchConfigurer getPathMatchConfigurer() {
           if (this.pathMatchConfigurer == null) {
               this.pathMatchConfigurer = new PathMatchConfigurer();
               configurePathMatch(this.pathMatchConfigurer);
           }
           return this.pathMatchConfigurer;
       }
   
       ...
   
       //================= ÷ʵ =================
       // Զ Interceptorʵ
       protected void addInterceptors(InterceptorRegistry registry) {
       }
   
       // Զ CorsMappingʵ
       protected void addCorsMappings(CorsRegistry registry) {
       }
   
       // Զ PathMatch
       protected void configurePathMatch(PathMatchConfigurer configurer) {
       }
       ...
   
   }
   
   

   ԿķΪࣺ

   • XxxAware ķXxxAware ӿ spring ṩbean ʼʱص
   • @Bean עķ spring bean bean ʱ getXxx
   • getXxx ȡ÷ڸ÷У spring ṩĬãԼ addXxx/configureXxx Զã
   • addXxx/configureXxx ʵ֣ springmvc Զá

ܽ 4 Ĺϵ

ĸĹϵ@EnableWebMvc ִ̾һĿȻˣܽ£

1. @EnableWebMvc spring DelegatingWebMvcConfiguration

2. DelegatingWebMvcConfiguration а @Autowired עķ setConfigurers(List<WebMvcConfigurer>) spring bean лִУΪȡ WebMvcConfigurer bean õ DelegatingWebMvcConfiguration У

3. DelegatingWebMvcConfiguration ̳ WebMvcConfigurationSupport spring bean лᴦ WebMvcConfigurationSupport @Bean עķַȽ϶࣬ requestMappingHandlerMapping()``mvcPathMatcher ȣЩ smvc Ĺ

4. ڴ WebMvcConfigurationSupport @Bean עķʱ getXxx() ȡãð spring ṩĬüԶãgetXxx() WebMvcConfigurationSupport ṩ

5. ڵ WebMvcConfigurationSupport#getXxx() ȡԶʱ addXxx()/configureXxx()÷ WebMvcConfigurationSupport ǿշ߼ (Ҳ DelegatingWebMvcConfiguration) ṩյ÷ʽִе 2 ȡ WebMvcConfigurer addXxx()/configureXxx()

ͼʾ

springmvc ܣԶʱǿô:

1. ʽ 1ʹ @EnableWebMvc ע mvc ܣʵ WebMvcConfigurerԶ

   Copy

   // ʹ@EnableWebMvcעmvc
   @Component
   @EnableWebMvc
   public class MvcConfig {
       ...
   }
   
   // ʵ WebMvcConfigurerԶ
   @Component
   public class MyWebMvcConfigurer implements WebMvcConfigurer {
   
       // дWebMvcConfigurerԶ
   }
   
   

2. ʽ 2ʵ WebMvcConfigurationSupport ࣬де÷

   Copy

   @Component
   public class MyWebMvcConfigurationSupport extends WebMvcConfigurationSupport {
       // д÷Զ
   
   }
   
   

   ַʽʵ WebMvcConfigurer ԶþͲЧˣԶֻ WebMvcConfigurationSupport á

springmvc ṩЩأ WebMvcConfigurer ṩķ

• configurePathMatch·
• configureContentNegotiationЭ
• configureAsyncSupport
• configureDefaultServletHandlingĬϾ̬Դ
• addFormattersעԶת
• addInterceptors
• addResourceHandlersԴ
• addCorsMappingsCORS
• addViewControllersͼת
• configureViewResolversͼ
• addArgumentResolversԶ巽
• addReturnValueHandlersԶ巵ؽ
• configureMessageConvertersϢתػḲĬע HttpMessageConverter
• extendMessageConvertersϢתһԶ HttpMessageConverter.
• configureHandlerExceptionResolvers쳣ת
• extendHandlerExceptionResolvers쳣ת
• getValidator:
• getMessageCodesResolver

ҪֻҪдط ɡ

WebMvcConfigurationSupport Щ Bean @Bean עķ£

• public RequestMappingHandlerMapping requestMappingHandlerMapping(...)
• public PathMatcher mvcPathMatcher()
• public UrlPathHelper mvcUrlPathHelper()
• public ContentNegotiationManager mvcContentNegotiationManager()
• public HandlerMapping viewControllerHandlerMapping(...)
• public BeanNameUrlHandlerMapping beanNameHandlerMapping(...)
• public RouterFunctionMapping routerFunctionMapping(...)
• public HandlerMapping resourceHandlerMapping(...)
• ResourceUrlProvider mvcResourceUrlProvider()
• public HandlerMapping defaultServletHandlerMapping()
• public RequestMappingHandlerAdapter requestMappingHandlerAdapter(...)
• public HandlerFunctionAdapter handlerFunctionAdapter()
• public FormattingConversionService mvcConversionService()
• public Validator mvcValidator()
• public CompositeUriComponentsContributor mvcUriComponentsContributor(...)
• public HttpRequestHandlerAdapter httpRequestHandlerAdapter()
• public SimpleControllerHandlerAdapter simpleControllerHandlerAdapter()
• public HandlerExceptionResolver handlerExceptionResolver(...)
• public ViewResolver mvcViewResolver(...)
• HandlerMappingIntrospector mvcHandlerMappingIntrospector()

Щ springmvc õһЩľݾͲչˡ

4. ܽ

ݱȽӣṩһ springmvc demoȻ demo 0 xml ԭ (Ҳ servlet 3.0 淶Ž @EnableWebMvc Ĺܣؽ WebMvcConfigurationSupport á

ԭӣhttps://my.oschina.net/funcy/blog/4696657 ߸ˮƽд֮ӭָԭףҵתϵ߻Ȩҵתע