@ControllerAdvice注解使用及原理探究

@RestControllerAdvice
@Slf4j
public class GlobalExceptionHandler {
// 这里就是对各个层返回的异常进行统一捕获处理
@ExceptionHandler(value = BusinessException.class)
public ResponseData bizException(BusinessException e){
        log.error("业务异常记录",e);
        return ResponseData.error(e.getCode(),e.getMessage());
}
}
//业务异常处代码示例：
if(CollectionUtil.isNotEmpty(companies)){
// 通过BusinessExceptionEnum枚举对业务异常进行统一管理
throw new BusinessException(BusinessExceptionEnum.ERROR_10003);
}

@RestControllerAdvice
@Slf4j
public class GlobalExceptionHandler {
// 将前端传入的字符串时间格式转换为LocalDate时间  
@InitBinder
    protected void initBinder(WebDataBinder binder) {
//将前端传入的字符串格式时间数据转为LocalDate格式的数据
        binder.registerCustomEditor(LocalDate.class, new PropertyEditorSupport() {
            @Override
            public void setAsText(String text) throws IllegalArgumentException {
                setValue(LocalDate.parse(text, DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)));
            }
        });
//将前端传入的字符串格式时间数据转为LocalDateTime格式的数据
        binder.registerCustomEditor(LocalDateTime.class, new PropertyEditorSupport() {
            @Override
            public void setAsText(String text) throws IllegalArgumentException {
                setValue(LocalDateTime.parse(text, DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)));
            }
        });
//将前端传入的字符串格式时间数据转为LocalTim格式的数据
        binder.registerCustomEditor(LocalTime.class, new PropertyEditorSupport() {
            @Override
            public void setAsText(String text) throws IllegalArgumentException {
                setValue(LocalTime.parse(text, DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));
            }
        });
    }
}
// controller进行参数绑定
public ResponseData> listWorkCalendar(@RequestParam LocalDate  date){}

// 这里@ModelAttribute("loginUser")标注的modelAttribute()方法表示会在Controller方法之前将user设置到contoller里的已绑定参数里
    @ModelAttribute("loginUser")
    public User setLoginUser(HttpServletRequest request) {
        return LoginContextUtils.getLoginUser(request);
    }
// 使用
    @PostMapping("/list")
    public ResponseData> listEmployee(@ModelAttribute("loginUser") User user, @RequestBody EmployeeSearch employeeSearch){
        return ResponseData.success(employeeService.listEmployee(user, employeeSearch));
    }

public class DispatcherServlet extends FrameworkServlet {
    // ......
    protected void initStrategies(ApplicationContext context) {
        initMultipartResolver(context);
        initLocaleResolver(context);
        initThemeResolver(context);
        initHandlerMappings(context);
//请求处理的adapter
        initHandlerAdapters(context);
// 异常响应处理的resolver
        initHandlerExceptionResolvers(context);
        initRequestToViewNameTranslator(context);
        initViewResolvers(context);
        initFlashMapManager(context);
    }
    // ......
}

@Override
    public void afterPropertiesSet() {
        // Do this first, it may add ResponseBody advice beans
// 这里会添加ResponseBody advice beans
        initControllerAdviceCache();

        if (this.argumentResolvers == null) {
            List resolvers = getDefaultArgumentResolvers();
            this.argumentResolvers = new HandlerMethodArgumentResolverComposite().addResolvers(resolvers);
        }
        if (this.initBinderArgumentResolvers == null) {
            List resolvers = getDefaultInitBinderArgumentResolvers();
            this.initBinderArgumentResolvers = new HandlerMethodArgumentResolverComposite().addResolvers(resolvers);
        }
        if (this.returnValueHandlers == null) {
            List handlers = getDefaultReturnValueHandlers();
            this.returnValueHandlers = new HandlerMethodReturnValueHandlerComposite().addHandlers(handlers);
        }
    }
// 这里找到contollerAdvice注解的类，缓存里面的方法
private void initControllerAdviceCache() {
        if (getApplicationContext() == null) {
            return;
        }
// 找到@ControllerAdvice注解标注的类
        List adviceBeans = ControllerAdviceBean.findAnnotatedBeans(getApplicationContext());

        List