在SpringBoot里自定义Spring MVC配置的三种方法

importorg.springframework.context.annotation.Configuration;
importorg.springframework.web.servlet.config.annotation.WebMvcConfigurer;
// 标记这是配置类，SpringBoot 启动时会扫描并加载
@Configuration
publicclassCustomWebMvcConfigimplementsWebMvcConfigurer{
// 下面重写需要自定义的方法即可
// 自定义静态资源路径、添加拦截器、配置消息转换器……
}

importorg.springframework.context.annotation.Configuration;
importorg.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
importorg.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@Configuration
publicclassCustomWebMvcConfigimplementsWebMvcConfigurer{
// 自定义静态资源配置
@Override
publicvoidaddResourceHandlers(ResourceHandlerRegistry registry){
// 1. 添加自定义静态资源路径：classpath:/images/
// addResourceHandler：前端访问路径前缀
// addResourceLocations：本地资源实际路径
        registry.addResourceHandler("/images/**")// 前端访问 http://localhost:8080/images/xxx.jpg
addResourceLocations("classpath:/images/");// 对应项目里的 src/main/resources/images/
// 2. 覆盖默认静态资源路径（可选，不推荐，保留默认更灵活）
// registry.addResourceHandler("/**")
//         .addResourceLocations("classpath:/my-static/");
}
}

importjakarta.servlet.http.HttpServletRequest;
importjakarta.servlet.http.HttpServletResponse;
importorg.springframework.web.servlet.HandlerInterceptor;
importorg.springframework.web.servlet.ModelAndView;
// 自定义登录拦截器
publicclassLoginInterceptorimplementsHandlerInterceptor{
// 请求处理前执行（核心逻辑写这里）
@Override
publicbooleanpreHandle(HttpServletRequest request,HttpServletResponse response,Object handler)throwsException{
// 模拟：从请求头获取 token，判断是否登录
String token = request.getHeader("token");
if(token ==null||!"admin123".equals(token)){
// 未登录，返回 401 状态码
            response.setStatus(401);
            response.getWriter().write("未登录，请先登录！");
returnfalse;// 拦截请求，不往下走
}
returntrue;// 放行请求
}
// 请求处理后执行（可选）
@Override
publicvoidpostHandle(HttpServletRequest request,HttpServletResponse response,Object handler,ModelAndView modelAndView)throwsException{
HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
}
// 整个请求完成后执行（可选，比如清理资源）
@Override
publicvoidafterCompletion(HttpServletRequest request,HttpServletResponse response,Object handler,Exception ex)throwsException{
HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
}
}

importorg.springframework.context.annotation.Bean;
importorg.springframework.context.annotation.Configuration;
importorg.springframework.web.servlet.config.annotation.InterceptorRegistry;
importorg.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@Configuration
publicclassCustomWebMvcConfigimplementsWebMvcConfigurer{
// 把拦截器注册为 Bean，Spring 才能管理
@Bean
publicLoginInterceptorloginInterceptor(){
returnnewLoginInterceptor();
}
// 注册拦截器，并配置拦截规则
@Override
publicvoidaddInterceptors(InterceptorRegistry registry){
        registry.addInterceptor(loginInterceptor())
.addPathPatterns("/**")// 拦截所有请求
.excludePathPatterns("/login","/hello");// 排除登录、hello 接口（不拦截）
}
}

importcom.fasterxml.jackson.databind.ObjectMapper;
importcom.fasterxml.jackson.databind.SerializationFeature;
importcom.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
importcom.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;
importorg.springframework.context.annotation.Bean;
importorg.springframework.context.annotation.Configuration;
importorg.springframework.http.converter.HttpMessageConverter;
importorg.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
importorg.springframework.web.servlet.config.annotation.WebMvcConfigurer;
importjava.time.LocalDateTime;
importjava.time.format.DateTimeFormatter;
importjava.util.List;
@Configuration
publicclassCustomWebMvcConfigimplementsWebMvcConfigurer{
// 自定义 JSON 消息转换器
@Override
publicvoidconfigureMessageConverters(List<HttpMessageConverter<?>> converters){
// 1. 创建 Jackson 对象映射器，自定义序列化规则
ObjectMapper objectMapper =newObjectMapper();
// 处理 LocalDateTime 日期格式
JavaTimeModule javaTimeModule =newJavaTimeModule();
        javaTimeModule.addSerializer(LocalDateTime.class,
newLocalDateTimeSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
        objectMapper.registerModule(javaTimeModule);
// 关闭默认的日期序列化（避免转成时间戳）
        objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
// 2. 创建自定义的消息转换器
MappingJackson2HttpMessageConverter converter =newMappingJackson2HttpMessageConverter();
        converter.setObjectMapper(objectMapper);
// 3. 把自定义转换器加到列表最前面（优先级最高）
        converters.add(0, converter);
}
}