关于SpringMVC自动配置

2021-03-17 10:07:16 浏览数 (1)

https://docs.spring.io/spring-boot/docs/1.5.10.RELEASE/reference/htmlsingle/#boot-features-developing-web-applications

1. Spring MVC auto-configuration

Spring Boot 自动配置好了SpringMVC

以下是SpringBoot对SpringMVC的默认配置:==(WebMvcAutoConfiguration)==

  • Inclusion of ContentNegotiatingViewResolver and BeanNameViewResolver beans.
  • 自动配置了ViewResolver(视图解析器:根据方法的返回值得到视图对象(View),视图对象决定如何渲染(转发?重定向?))
  • ContentNegotiatingViewResolver:组合所有的视图解析器的;
  • ==如何定制:我们可以自己给容器中添加一个视图解析器;自动的将其组合进来;==
  • Support for serving static resources, including support for WebJars (see below).静态资源文件夹路径,webjars
  • Static index.html support. 静态首页访问
  • Custom Favicon support (see below). favicon.ico
  • 自动注册了 of Converter, GenericConverter, Formatter beans.
  • Converter:转换器; public String hello(User user):类型转换使用Converter
  • Formatter 格式化器; 2017.12.17===Date;
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		@Bean
		@ConditionalOnProperty(prefix = "spring.mvc", name = "date-format")//在文件中配置日期格式化的规则
		public Formatter<Date> dateFormatter() {
			return new DateFormatter(this.mvcProperties.getDateFormat());//日期格式化组件
		}
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==自己添加的格式化器转换器,我们只需要放在容器中即可==
  • Support for HttpMessageConverters (see below).
  • HttpMessageConverter:SpringMVC用来转换Http请求和响应的;User---Json;
  • HttpMessageConverters 是从容器中确定;获取所有的HttpMessageConverter;
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==自己给容器中添加HttpMessageConverter,只需要将自己的组件注册容器中(@Bean,@Component)==
  • Automatic registration of MessageCodesResolver (see below).定义错误代码生成规则
  • Automatic use of a ConfigurableWebBindingInitializer bean (see below).

==我们可以配置一个ConfigurableWebBindingInitializer来替换默认的;(添加到容器)==

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初始化WebDataBinder;

请求数据=====JavaBean;

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org.springframework.boot.autoconfigure.web:web的所有自动场景;

If you want to keep Spring Boot MVC features, and you just want to add additional MVC configuration (interceptors, formatters, view controllers etc.) you can add your own @Configuration class of type WebMvcConfigurerAdapter, but without @EnableWebMvc. If you wish to provide custom instances of RequestMappingHandlerMapping, RequestMappingHandlerAdapter or ExceptionHandlerExceptionResolver you can declare a WebMvcRegistrationsAdapter instance providing such components.

If you want to take complete control of Spring MVC, you can add your own @Configuration annotated with @EnableWebMvc.

2、扩展SpringMVC

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    <mvc:view-controller path="/hello" view-name="success"/>
    <mvc:interceptors>
        <mvc:interceptor>
            <mvc:mapping path="/hello"/>
            <bean></bean>
        </mvc:interceptor>
    </mvc:interceptors>

==编写一个配置类(@Configuration),是WebMvcConfigurerAdapter类型;不能标注@EnableWebMvc==;

既保留了所有的自动配置,也能用我们扩展的配置;

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//使用WebMvcConfigurerAdapter可以来扩展SpringMVC的功能
@Configuration
public class MyMvcConfig extends WebMvcConfigurerAdapter {

    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
       // super.addViewControllers(registry);
        //浏览器发送 /atguigu 请求来到 success
        registry.addViewController("/atguigu").setViewName("success");
    }
}

原理:

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1)、WebMvcAutoConfiguration是SpringMVC的自动配置类
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2)、在做其他自动配置时会导入;@Import(**EnableWebMvcConfiguration**.class)
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    @Configuration
	public static class EnableWebMvcConfiguration extends DelegatingWebMvcConfiguration {
      private final WebMvcConfigurerComposite configurers = new WebMvcConfigurerComposite();

	 //从容器中获取所有的WebMvcConfigurer
      @Autowired(required = false)
      public void setConfigurers(List<WebMvcConfigurer> configurers) {
          if (!CollectionUtils.isEmpty(configurers)) {
              this.configurers.addWebMvcConfigurers(configurers);
            	//一个参考实现;将所有的WebMvcConfigurer相关配置都来一起调用;  
            	@Override
             // public void addViewControllers(ViewControllerRegistry registry) {
              //    for (WebMvcConfigurer delegate : this.delegates) {
               //       delegate.addViewControllers(registry);
               //   }
              }
          }
	}
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3)、容器中所有的WebMvcConfigurer都会一起起作用;
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4)、我们的配置类也会被调用;
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效果:SpringMVC的自动配置和我们的扩展配置都会起作用;

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