但是使用RequestMappingHandlerAdapter后无法识别@RequestMapping注解

如果你使用了`RequestMappingHandlerAdapter`但是无法识别`@RequestMapping`注解，可能是因为你没有在配置类中添加`<mvc:annotation-driven/>`配置。这个配置会启用Spring MVC的注解驱动，包括`@RequestMapping`注解的识别和解析。你可以在Spring MVC的配置文件中添加如下配置：

<mvc:annotation-driven/>

或者如果你使用的是Java Config，可以在`WebMvcConfigurer`的实现类中添加如下方法：

@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {
    // ...

    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

    @Override
    public void configureViewResolvers(ViewResolverRegistry registry) {
        // ...
    }

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        // ...
    }

    @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
        // ...
    }

    @Override
    public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
        // ...
    }

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        // ...
    }

    @Override
    public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
        // ...
    }

    @Override
    public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
        // ...
    }

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // ...
    }

    @Override
    public void configureAsyncSupport(AsyncSupportConfigurer configurer) {
        // ...
    }

    @Override
    public void configurePathMatch(PathMatchConfigurer configurer) {
        configurer.setUseSuffixPatternMatch(false);
        configurer.setUseTrailingSlashMatch(true);
    }

    @Override
    public void addCorsMappings(CorsRegistry registry) {
        // ...
    }

    @Override
    public void configureViewControllers(ViewControllerRegistry registry) {
        // ...
    }

    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        // ...
    }

    @Override
    public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
        // ...
    }

    @Override
    public void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {
        // ...
    }

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        // ...
    }

    @Override
    public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
        // ...
    }

    @Override
    public void addFormatters(FormatterRegistry registry) {
        // ...
    }

    @Override
    public void configureAsyncSupport(AsyncSupportConfigurer configurer) {
        // ...
    }

    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        // ...
    }

    @Override
    public void configurePathMatch(PathMatchConfigurer configurer) {
        configurer.setUseSuffixPatternMatch(false);
        configurer.setUseTrailingSlashMatch(true);
    }

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // ...
    }

    @Override
    public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
        // ...
    }

    @Override
    public void addCorsMappings(CorsRegistry registry) {
        // ...
    }

    @Override
    public void configureViewResolvers(ViewResolverRegistry registry) {
        // ...
    }

    @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
        // ...
    }

    @Override
    public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
        // ...
    }

    // Add this method to enable Spring MVC annotation-driven
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        // ...
    }
}

确保在`configureMessageConverters`方法中添加了`<mvc:annotation-driven/>`配置。这样就能够启用Spring MVC的注解驱动，使得`@RequestMapping`注解能够被正确识别和解析。