springmvc控制器方法参数解析的那些事儿

spring  mvc是如何对控制器方法里面的参数进行处理的？ 

还得从@EnableWebMvc这个注解说起。 

启动这Mvc容器，自然就会加载WebMvcConfigurationSupport这个配置类，这个类做的事儿太多了，就看如下这段代码

@Bean
public RequestMappingHandlerAdapter requestMappingHandlerAdapter(
        @Qualifier("mvcContentNegotiationManager") ContentNegotiationManager contentNegotiationManager,
        @Qualifier("mvcConversionService") FormattingConversionService conversionService,
        @Qualifier("mvcValidator") Validator validator) {

    RequestMappingHandlerAdapter adapter = createRequestMappingHandlerAdapter();
    adapter.setContentNegotiationManager(contentNegotiationManager);
    // 配置消息转换器
    adapter.setMessageConverters(getMessageConverters());
    adapter.setWebBindingInitializer(getConfigurableWebBindingInitializer(conversionService, validator));
    // 配置自定义参数解析器
    adapter.setCustomArgumentResolvers(getArgumentResolvers());
    // 配置返回值处理器
    adapter.setCustomReturnValueHandlers(getReturnValueHandlers());

    if (jackson2Present) {
        adapter.setRequestBodyAdvice(Collections.singletonList(new JsonViewRequestBodyAdvice()));
        adapter.setResponseBodyAdvice(Collections.singletonList(new JsonViewResponseBodyAdvice()));
    }

    AsyncSupportConfigurer configurer = new AsyncSupportConfigurer();
    configureAsyncSupport(configurer);
    if (configurer.getTaskExecutor() != null) {
        adapter.setTaskExecutor(configurer.getTaskExecutor());
    }
    if (configurer.getTimeout() != null) {
        adapter.setAsyncRequestTimeout(configurer.getTimeout());
    }
    adapter.setCallableInterceptors(configurer.getCallableInterceptors());
    adapter.setDeferredResultInterceptors(configurer.getDeferredResultInterceptors());

    return adapter;
}

还有段很重要的代码，如下：

@Bean
public RequestMappingHandlerMapping requestMappingHandlerMapping(
        @Qualifier("mvcContentNegotiationManager") ContentNegotiationManager contentNegotiationManager,
        @Qualifier("mvcConversionService") FormattingConversionService conversionService,
        @Qualifier("mvcResourceUrlProvider") ResourceUrlProvider resourceUrlProvider) {

    RequestMappingHandlerMapping mapping = createRequestMappingHandlerMapping();
    mapping.setOrder(0);
    mapping.setInterceptors(getInterceptors(conversionService, resourceUrlProvider));
    mapping.setContentNegotiationManager(contentNegotiationManager);
    mapping.setCorsConfigurations(getCorsConfigurations());

    PathMatchConfigurer configurer = getPathMatchConfigurer();

    Boolean useSuffixPatternMatch = configurer.isUseSuffixPatternMatch();
    if (useSuffixPatternMatch != null) {
        mapping.setUseSuffixPatternMatch(useSuffixPatternMatch);
    }
    Boolean useRegisteredSuffixPatternMatch = configurer.isUseRegisteredSuffixPatternMatch();
    if (useRegisteredSuffixPatternMatch != null) {
        mapping.setUseRegisteredSuffixPatternMatch(useRegisteredSuffixPatternMatch);
    }
    Boolean useTrailingSlashMatch = configurer.isUseTrailingSlashMatch();
    if (useTrailingSlashMatch != null) {
        mapping.setUseTrailingSlashMatch(useTrailingSlashMatch);
    }

    UrlPathHelper pathHelper = configurer.getUrlPathHelper();
    if (pathHelper != null) {
        mapping.setUrlPathHelper(pathHelper);
    }
    PathMatcher pathMatcher = configurer.getPathMatcher();
    if (pathMatcher != null) {
        mapping.setPathMatcher(pathMatcher);
    }
    Map<String, Predicate<Class<?>>> pathPrefixes = configurer.getPathPrefixes();
    if (pathPrefixes != null) {
        mapping.setPathPrefixes(pathPrefixes);
    }

    return mapping;
}

未完待续。。。。