springboot 返回结果统一大小写

可以在SpringBoot项目中配置一个返回结果统一大小写的拦截器，拦截器的实现可以参考以下示例代码：

public class ResultCaseInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        if (modelAndView != null && modelAndView.getModelMap() != null) {
            Map<String, Object> modelMap = modelAndView.getModelMap();
            Map<String, Object> newModelMap = new HashMap<>();
            for (Map.Entry<String, Object> entry : modelMap.entrySet()) {
                String key = entry.getKey();
                Object value = entry.getValue();
                if (value instanceof String) {
                    newModelMap.put(key, ((String) value).toLowerCase());
                } else {
                    newModelMap.put(key, value);
                }
            }
            modelAndView.getModelMap().clear();
            modelAndView.addAllObjects(newModelMap);
        }
    }

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

在SpringBoot项目中注册拦截器，使其生效：

@Configuration
public class InterceptorConfig implements WebMvcConfigurer {

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new ResultCaseInterceptor()).addPathPatterns("/**");
    }
}

这样，返回结果中所有的字符串都会被转换成小写。如果需要转换成大写，只需要修改拦截器中的逻辑即可。