@ControllerAdvice注解，可以对Controller中被 @RequestMapping注解的方法加一些逻辑处理。最常用的就是异常处理。

具体使用

1、定义异常处理类，可以返回json格式数据或者跳转到错误页面

返回json数据：

@ControllerAdvice
public class CustomExceptionHandler {

    @ResponseBody
    @ExceptionHandler(value = Exception.class)
    public Map errorHandler(Exception e) {
        Map map = new HashMap();
        map.put("code", 400);
        //根据异常类型返回信息
        if(e instanceof MyException){
            map.put("msg","这是自定义异常");
        }
        return map;
    }
}

或者返回页面

@ExceptionHandler(value = MyException.class)
public ModelAndView myErrorHandler(MyException e) {
    ModelAndView modelAndView = new ModelAndView();
    //指定错误页面的模板页
    modelAndView.setViewName("error");
    modelAndView.addObject("code", e.getCode());
    modelAndView.addObject("msg", e.getMsg());
    return modelAndView;
}

2、自定义异常类

//自定义异常类
@Data
public class MyException extends RuntimeException {
    private long code;
    private String msg;

    public MyException(Long code, String msg){
        super(msg);
        this.code = code;
        this.msg = msg;
    }

    public MyException(String msg){
        super(msg);
        this.msg = msg;
    }
}

项目中的具体使用，记录异常信息，浏览器相应错误信息或者跳转到错误页面：

@ControllerAdvice(annotations = Controller.class)
public class ExceptionAdvice {

    private static final Logger logger = LoggerFactory.getLogger(ExceptionAdvice.class);

    @ExceptionHandler({Exception.class})
    public void handleException(Exception e, HttpServletRequest request, HttpServletResponse response) throws IOException {
        logger.error("服务器发生异常: " + e.getMessage());
        for (StackTraceElement element : e.getStackTrace()) {
            logger.error(element.toString());
        }

        //requestedWith为null，则为同步请求；requestedWith为XMLHttpRequest，则为Ajax请求
        String xRequestedWith = request.getHeader("x-requested-with");
        if ("XMLHttpRequest".equals(xRequestedWith)) {
            response.setContentType("application/plain;charset=utf-8");
            PrintWriter writer = response.getWriter();
            writer.write(CommunityUtil.getJSONString(1, "服务器异常!"));
        } else {
            //重定向到错误页面
            response.sendRedirect(request.getContextPath() + "/error");
        }
    }

}