Springboot学习:SpringMVC自动配置
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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
andBeanNameViewResolver
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;
@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
}
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;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)
初始化WebDataBinder; 请求数据=====JavaBean;
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
.
扩展SpringMVC
<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;
//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:
1)、WebMvcAutoConfiguration是SpringMVC的自动配置类
2)、在做其他自动配置时会导入;@Import(EnableWebMvcConfiguration.class)
@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);
// }
}
}
}
3)、容器中所有的WebMvcConfigurer都会一起起作用;
4)、我们的配置类也会被调用;
效果:SpringMVC的自动配置和我们的扩展配置都会起作用;
全面接管SpringMVC
SpringBoot对SpringMVC的自动配置不需要了,所有都是我们自己配置;所有的SpringMVC的自动配置都失效了
我们需要在配置类中添加@EnableWebMvc即可;
//使用WebMvcConfigurerAdapter可以来扩展SpringMVC的功能
@EnableWebMvc
@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:
为什么@EnableWebMvc自动配置就失效了;
1)@EnableWebMvc的核心
@Import(DelegatingWebMvcConfiguration.class)
public @interface EnableWebMvc {
2)、
@Configuration
public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
3)、
@Configuration
@ConditionalOnWebApplication
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class,
WebMvcConfigurerAdapter.class })
//容器中没有这个组件的时候,这个自动配置类才生效
@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
@AutoConfigureAfter({ DispatcherServletAutoConfiguration.class,
ValidationAutoConfiguration.class })
public class WebMvcAutoConfiguration {
4)、@EnableWebMvc将WebMvcConfigurationSupport组件导入进来;
5)、导入的WebMvcConfigurationSupport只是SpringMVC最基本的功能;