springboot中springmvc的自定义配置

自己编写配置类并实现WebMvcConfigurer接口

/**
 * 使用WebMvcConfigurer可以来扩展SpringMVC的功能
 * @EnableWebMvc   全面接管SpringMVC，这个注解一般不用
 */
@Configuration
public class MyMvcConfig implements WebMvcConfigurer {
    /**
     * 添加视图解析器
     */
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/lalala").setViewName("success");
        registry.addViewController("/").setViewName("login");
        registry.addViewController("/index.html").setViewName("login");
        registry.addViewController("/main.html").setViewName("dashboard");
    }

    /**
     * 注册拦截器
     */
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        //SpringBoot已经做好了静态资源映射
        registry.addInterceptor(new LoginHandlerInterceptor()).addPathPatterns("/**")
                .excludePathPatterns("/index.html","/","/user/login");
    }

    /**
     * 自定义国际化化区域解析器
     */
    @Bean
    public LocaleResolver localeResolver(){
        return new MyLocaleResolver();
    }

}

/**
 * 自定义拦截器，登陆检查
 */
public class LoginHandlerInterceptor implements HandlerInterceptor {
    
    //目标方法执行之前
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        Object user = request.getSession().getAttribute("loginUser");
        if(user == null){
            //未登陆，返回登陆页面
            request.setAttribute("msg","没有权限请先登陆");
            request.getRequestDispatcher("/index.html").forward(request,response);
            return false;
        }else{
            //已登陆，放行请求
            return true;
        }

    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}

/**
 * 自定义区域解析器，可以在连接上携带区域信息
 */
public class MyLocaleResolver implements LocaleResolver {

    @Override
    public Locale resolveLocale(HttpServletRequest request) {
        String l = request.getParameter("l");
        Locale locale = Locale.getDefault();
        if(!StringUtils.isEmpty(l)){
            String[] split = l.split("_");
            locale = new Locale(split[0],split[1]);
        }
        return locale;
    }

    @Override
    public void setLocale(HttpServletRequest request, HttpServletResponse response, Locale locale) {

    }
}

这种配置方式会和springboot的自动配置同时起作用，推荐使用，而之所以会同时起作用的原理如下WebMvcAutoConfiguration中有一个静态内部类EnableWebMvcConfiguration

@Configuration(proxyBeanMethods = false)
    public static class EnableWebMvcConfiguration extends DelegatingWebMvcConfiguration implements ResourceLoaderAware {

}

在EnableWebMvcConfiguration的继承的DelegatingWebMvcConfiguration类中

@Configuration(
    proxyBeanMethods = false
)
public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
    private final WebMvcConfigurerComposite configurers = new WebMvcConfigurerComposite();

    public DelegatingWebMvcConfiguration() {
    }

    @Autowired(
        required = false
    )
    // 可以看到这里是将所有实现的WebConfigurer加入配置中
    public void setConfigurers(List<WebMvcConfigurer> configurers) {
        if (!CollectionUtils.isEmpty(configurers)) {
            this.configurers.addWebMvcConfigurers(configurers);
        }

    }
}

所以我们自定义一个类实现WebMvcConfigurer，并加入配置中就会自动生效，并且是和springboot的自动配置共同起作用