SpringBoot Web/API的通用异常处理[嗡汤圆的小笔记]

淩亂°似流年 2022-07-11 06:44 210阅读 0赞

# view的异常处理 #

SpringBoot Web项目中对于view的默认错误信息页如下：  
![这里写图片描述][SouthEast]

并不十分友好，因此需要对异常进行自定义处理，步骤如下：

1.  建立`@ControllerAdvice` Bean。并分别为各异常类制定处理方式。为简单起见，本处仅对Exception（500错误）和NoHandlerFoundException（即404错误）进行处理
2.  设置ServletDispatcher，允许404异常抛出（若不做此设置，NoHandlerFoundException不会被捕获）

代码如下：

/*STEP 1 : 声明@ControllerAdvice Bean*/
    @ControllerAdvice
    public class ErrorView { 
        @ExceptionHandler(value=Exception.class)
        public ModelAndView defaultErrorHandler(HttpServletRequest request, Exception e) throws Exception {
    
                ModelAndView view = new ModelAndView();
                view.addObject("ERRORCODE", 500);
                view.addObject("ERRORMSG", e.getMessage());
                view.addObject("URL", request.getRequestURL());
                view.setViewName("error");
                return view;
    
        }
        @ExceptionHandler(value=NoHandlerFoundException.class)
        public ModelAndView pageNoFoundHandler(HttpServletRequest request, Exception e) throws Exception {
    
                ModelAndView view = new ModelAndView();
                view.addObject("ERRORCODE", 404);
                view.addObject("ERRORMSG", "页面未找到");
                view.addObject("URL", request.getRequestURL());
                view.setViewName("error");
                return view;
        }
    }
    
    
    /*STEP - 2 : 设置DispatcherServlet的404异常抛出*/
    
    @EnableScheduling
    @SpringBootApplication
    public class WebProxy { 
        public static void main(String[] args) {
            ApplicationContext ctx = SpringApplication.run(WebProxy.class, args);
            // 自定义处理404异常
            DispatcherServlet servlet = (DispatcherServlet) ctx.getBean("dispatcherServlet");
            servlet.setThrowExceptionIfNoHandlerFound(true);
        }
    }

在此基础上，制作一个异常页面error.html即可。代码如下（此处借助thymeleaf模板引擎）：

<!DOCTYPE html>
    <html xmlns="http://www.w3.org/1999/xhtml" xmlns:th="http://www.thymeleaf.org" xmlns:sec="http://www.thymeleaf.org/thymeleaf-extras-springsecurity3">
    <head>
    <title>ERROR</title>
    
    <div th:include="layout/common :: header"></div>
    <div th:include="layout/common :: lib"></div>
    
    </head>
    
    <body>
        <header class="header">
            <h1>
                <a href="#" class="sel-station">错误页面</a>
            </h1>
        </header>
        <div class="content" id="app">
            <div class="media"><img th:src="@{/static/images/ico18.png}" width="100%" /></div>
            <div class="lobby-place">
                <section class="item">
                    <p th:text="'code:'+${ERRORCODE}">ERRORCODE</p>
                    <p th:text="'url:'+${URL}">
                        URL
                    </p>
                    <P th:text="'msg:'+${ERRORMSG}">
                        ERRORMSG
                    </P>
                    <a class="btn btn-block btn-primary" th:href="@{/view/index}">回首页</a>
                </section>
            </div>
        </div>
    </body>
    
    </html>

显示效果如下：  
![这里写图片描述][SouthEast 1]

# 增加API的异常处理 #

在增加通用处理前，首先先定义所有API的规范化数据结构。基本信息应包括：状态码statusCode, 状态信息statusMsg，数据data。代码如下：

public class ResultBean { 
    
        private int statusCode;
        private String statusMsg;
        private Object data;
    
        /*getter setter 省略*/
    }

定义statusCode == 0 为成功，则从data中获取数据，否则失败，从statusMsg中获取错误信息。  
同时，对于请求url地址统一定位于`/api/` 之下，这样既可通过url判断该请求属于视图还是API接口。

将返回的ModelAndView 改为Object，同时加上`@ResponseBody` 修改后的`@ControllerAdvice`如下

@ControllerAdvice
    public class ErrorView { 
        @ResponseBody
        @ExceptionHandler(value=Exception.class)
        public Object defaultErrorHandler(HttpServletRequest request, Exception e) throws Exception {
            if (!returnJson(request)) {
                ModelAndView view = new ModelAndView();
                view.addObject("ERRORCODE", 500);
                view.addObject("ERRORMSG", e.getMessage());
                view.addObject("URL", request.getRequestURL());
                view.setViewName("error");
                return view;
            } else {
                System.out.println("is json");
                ResultBean bean = new ResultBean();
                bean.setReturnCode(-1);
                bean.setReturnMsg("[api异常]" + e.getMessage());
                return bean;        
            }
        }   
        @ResponseBody
        @ExceptionHandler(value=NoHandlerFoundException.class)
        public Object pageNoFoundHandler(HttpServletRequest request, Exception e) throws Exception {
            if (!returnJson(request)) {
                ModelAndView view = new ModelAndView();
                view.addObject("ERRORCODE", 404);
                view.addObject("ERRORMSG", "页面未找到");
                view.addObject("URL", request.getRequestURL());
                view.setViewName("error");
                return view;
            } else {
                System.out.println("is json");
                ResultBean bean = new ResultBean();
                bean.setReturnCode(-1);
                bean.setReturnMsg("地址未找到");
                return bean;
            }
        }
        private boolean returnJson(HttpServletRequest request){
            System.out.println(request.getRequestURI());
            return request.getRequestURI().contains("/api/");
        }
    }

这样在调用Api出现异常时既可返回相应的错误信息。效果入下：  
![这里写图片描述][SouthEast 2]

![这里写图片描述][SouthEast 3]

[SouthEast]: /images/20220711/f85e341888914f73b203e62122152a59.png
[SouthEast 1]: /images/20220711/d7312260d15b4717a49931263f806d7f.png
[SouthEast 2]: /images/20220711/d7df71a1b7684d60a51ba51cd77665cb.png
[SouthEast 3]: /images/20220711/878cff24c81d4706b795461161db6e50.png