8. Unified exception handling (controller notifies @ControllerAdvice global configuration class, @ExceptionHandler handles exceptions uniformly)

• SpringBoot设计,如果出现错误404或500,Automatically call under a specific pathhtml页面(Paths and names are specific)./templates/error/404.html、/templates/error/500.html.This page is automatically called when there is an error in the program.
• But the error has async request error,Also want to log at the same time.Then use the unified processing method,即全局配置.使用HomeController,Add a request to get the error page,手动重定向路径.

    @RequestMapping(path = "/error", method = RequestMethod.GET)
    public String getErrorPage() {
    
        return "/error/500";
    }

在Controller下新建adviceNotification configuration package,新建ExceptionAdvice.用到两个注解：@ControllerAdvice,@ExceptionHandler.

• 是Controller全局配置类,Not to anyControllerdo the configuration again,can be done uniformlyController的全局配置.@ControllerAdvice用来修饰类.
• 异常处理方案**@ExceptionHandler**、绑定数据方案**@ModelAttribute**、绑定参数方案**@DataBinder**. They are both used to decorate methods.
• 这里只演示,统一处理异常（@ExceptionHandler）

// 是Controller全局配置类,Not to anyControllerdo the configuration again,can be done uniformlyController的全局配置[email protected]用来修饰类.
// 异常处理方案@ExceptionHandler、绑定数据方案@ModelAttribute、绑定参数方案@DataBinder. They are both used to decorate methods.
// 这里只演示,统一处理异常（@ExceptionHandler）
@ControllerAdvice(annotations = Controller.class) // 限定注解@Controller,Otherwise the component scans allbean
public class ExceptionAdvice {
    

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

    @ExceptionHandler({
    Exception.class})// 处理哪些异常？Exception是所有异常的父类,All exceptions are handled
    // 有异常controllerwill passException
    public void handleException(Exception e, HttpServletRequest request, HttpServletResponse response) throws IOException {
    

        // 记录日志
        logger.error("服务器发生异常：" + e.getMessage());//Unusual summary
        for (StackTraceElement element : e.getStackTrace()) {
    //Record the information of all stacks of exceptions
            logger.error(element.toString());
        }

        // 给浏览器响应
        // Depends what the request is,Want the server to return the web pagehtml/异步请求JSON(xml).Get it from the request header.
        String xRequestedWith = request.getHeader("x-requested-with");
        if ("XMLHttpRequest".equals(xRequestedWith)) {
    // 异步请求
            response.setContentType("application/plain;charset=utf-8");
            PrintWriter writer = response.getWriter();// 输出流
            writer.write(CommunityUtil.getJSONString(1,"服务器异常!"));// 输出JSON字符串
        }else{
    // 请求html,重定向到错误页面
            response.sendRedirect(request.getContextPath() + "/error");
        }

    }
}

Click on the Unconfigured page to appear404,并记录日志：

点击消息,浏览器请求页面,服务端出错500,并记录日志：

发送私信,异步请求,服务端出错,返回JSON字符串,并记录日志：