Spring Cloud中统一异常处理是怎么做的？

作者：BNDong

www.cnblogs.com/bndong/p/10135370.html

在启动应用时会发现在控制台打印的日志中出现了两个路径为 {[/error]} 的访问地址，当系统中发送异常错误时，Spring Boot 会根据请求方式分别跳转到以 JSON 格式或以界面显示的 /error 地址中显示错误信息。

2018-12-18 09:36:24.627  INFO 19040 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" ...
2018-12-18 09:36:24.632  INFO 19040 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" ...

默认异常处理

使用 AJAX 方式请求时返回的 JSON 格式错误信息。

{"timestamp": "2018-12-18T01:50:51.196+0000","status": 404,"error": "Not Found","message": "No handler found for GET /err404","path": "/err404"
}

使用浏览器请求时返回的错误信息界面。

自定义异常处理

引入依赖

<dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>1.2.54</version>
</dependency>
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-freemarker</artifactId>
</dependency>

fastjson 是 JSON 序列化依赖， spring-boot-starter-freemarker 是一个模板引擎，用于我们设置错误输出模板。

增加配置

properties

# 出现错误时, 直接抛出异常(便于异常统一处理，否则捕获不到404)
spring.mvc.throw-exception-if-no-handler-found=true
# 不要为工程中的资源文件建立映射
spring.resources.add-mappings=false

yml

spring:# 出现错误时, 直接抛出异常(便于异常统一处理，否则捕获不到404)mvc:throw-exception-if-no-handler-found: true# 不要为工程中的资源文件建立映射resources:add-mappings: false

新建错误信息实体

/*** 信息实体*/
public class ExceptionEntity implements Serializable {private static final long serialVersionUID = 1L;private String message;private int    code;private String error;private String path;@JSONField(format = "yyyy-MM-dd hh:mm:ss")private Date timestamp = new Date();public static long getSerialVersionUID() {return serialVersionUID;}public String getMessage() {return message;}public void setMessage(String message) {this.message = message;}public int getCode() {return code;}public void setCode(int code) {this.code = code;}public String getError() {return error;}public void setError(String error) {this.error = error;}public String getPath() {return path;}public void setPath(String path) {this.path = path;}public Date getTimestamp() {return timestamp;}public void setTimestamp(Date timestamp) {this.timestamp = timestamp;}
}

新建自定义异常

/*** 自定义异常*/
public class BasicException extends RuntimeException {private static final long serialVersionUID = 1L;private int code = 0;public BasicException(int code, String message) {super(message);this.code = code;}public int getCode() {return this.code;}
}

/*** 业务异常*/
public class BusinessException extends BasicException {private static final long serialVersionUID = 1L;public BusinessException(int code, String message) {super(code, message);}
}

BasicException 继承了 RuntimeException ，并在原有的 Message 基础上增加了错误码 code 的内容。而 BusinessException 则是在业务中具体使用的自定义异常类，起到了对不同的异常信息进行分类的作用。

新建 error.ftl 模板文件

位置：/src/main/resources/templates/ 用于显示错误信息

<!DOCTYPE html>
<html>
<head><meta name="robots" content="noindex,nofollow" /><meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=no"><style>h2{color: #4288ce;font-weight: 400;padding: 6px 0;margin: 6px 0 0;font-size: 18px;border-bottom: 1px solid #eee;}/* Exception Variables */.exception-var table{width: 100%;max-width: 500px;margin: 12px 0;box-sizing: border-box;table-layout:fixed;word-wrap:break-word;}.exception-var table caption{text-align: left;font-size: 16px;font-weight: bold;padding: 6px 0;}.exception-var table caption small{font-weight: 300;display: inline-block;margin-left: 10px;color: #ccc;}.exception-var table tbody{font-size: 13px;font-family: Consolas,"Liberation Mono",Courier,"微软雅黑";}.exception-var table td{padding: 0 6px;vertical-align: top;word-break: break-all;}.exception-var table td:first-child{width: 28%;font-weight: bold;white-space: nowrap;}.exception-var table td pre{margin: 0;}</style>
</head>
<body><div class="exception-var"><h2>Exception Datas</h2><table><tbody><tr><td>Code</td><td>${(exception.code)!}</td></tr><tr><td>Time</td><td>${(exception.timestamp?datetime)!}</td></tr><tr><td>Path</td><td>${(exception.path)!}</td></tr><tr><td>Exception</td><td>${(exception.error)!}</td></tr><tr><td>Message</td><td>${(exception.message)!}</td></tr></tbody></table>
</div>
</body>
</html>

编写全局异常控制类

/*** 全局异常控制类*/
@ControllerAdvice
public class GlobalExceptionHandler {/*** 404异常处理*/@ExceptionHandler(value = NoHandlerFoundException.class)@ResponseStatus(HttpStatus.NOT_FOUND)public ModelAndView errorHandler(HttpServletRequest request, NoHandlerFoundException exception, HttpServletResponse response) {return commonHandler(request, response,exception.getClass().getSimpleName(),HttpStatus.NOT_FOUND.value(),exception.getMessage());}/*** 405异常处理*/@ExceptionHandler(HttpRequestMethodNotSupportedException.class)public ModelAndView errorHandler(HttpServletRequest request, HttpRequestMethodNotSupportedException exception, HttpServletResponse response) {return commonHandler(request, response,exception.getClass().getSimpleName(),HttpStatus.METHOD_NOT_ALLOWED.value(),exception.getMessage());}/*** 415异常处理*/@ExceptionHandler(HttpMediaTypeNotSupportedException.class)public ModelAndView errorHandler(HttpServletRequest request, HttpMediaTypeNotSupportedException exception, HttpServletResponse response) {return commonHandler(request, response,exception.getClass().getSimpleName(),HttpStatus.UNSUPPORTED_MEDIA_TYPE.value(),exception.getMessage());}/*** 500异常处理*/@ExceptionHandler(value = Exception.class)public ModelAndView errorHandler (HttpServletRequest request, Exception exception, HttpServletResponse response) {return commonHandler(request, response,exception.getClass().getSimpleName(),HttpStatus.INTERNAL_SERVER_ERROR.value(),exception.getMessage());}/*** 业务异常处理*/@ExceptionHandler(value = BasicException.class)private ModelAndView errorHandler (HttpServletRequest request, BasicException exception, HttpServletResponse response) {return commonHandler(request, response,exception.getClass().getSimpleName(),exception.getCode(),exception.getMessage());}/*** 表单验证异常处理*/@ExceptionHandler(value = BindException.class)@ResponseBodypublic ExceptionEntity validExceptionHandler(BindException exception, HttpServletRequest request, HttpServletResponse response) {List<FieldError> fieldErrors = exception.getBindingResult().getFieldErrors();Map<String,String> errors = new HashMap<>();for (FieldError error:fieldErrors) {errors.put(error.getField(), error.getDefaultMessage());}ExceptionEntity entity = new ExceptionEntity();entity.setMessage(JSON.toJSONString(errors));entity.setPath(request.getRequestURI());entity.setCode(HttpStatus.INTERNAL_SERVER_ERROR.value());entity.setError(exception.getClass().getSimpleName());response.setStatus(HttpStatus.INTERNAL_SERVER_ERROR.value());return entity;}/*** 异常处理数据处理*/private ModelAndView commonHandler (HttpServletRequest request, HttpServletResponse response,String error, int httpCode, String message) {ExceptionEntity entity = new ExceptionEntity();entity.setPath(request.getRequestURI());entity.setError(error);entity.setCode(httpCode);entity.setMessage(message);return determineOutput(request, response, entity);}/*** 异常输出处理*/private ModelAndView determineOutput(HttpServletRequest request, HttpServletResponse response, ExceptionEntity entity) {if (!(request.getHeader("accept").contains("application/json")|| (request.getHeader("X-Requested-With") != null && request.getHeader("X-Requested-With").contains("XMLHttpRequest")))) {ModelAndView modelAndView = new ModelAndView("error");modelAndView.addObject("exception", entity);return modelAndView;} else {response.setStatus(HttpStatus.INTERNAL_SERVER_ERROR.value());response.setCharacterEncoding("UTF8");response.setHeader("Content-Type", "application/json");try {response.getWriter().write(ResultJsonTools.build(ResponseCodeConstant.SYSTEM_ERROR,ResponseMessageConstant.APP_EXCEPTION,JSONObject.parseObject(JSON.toJSONString(entity))));} catch (IOException e) {e.printStackTrace();}return null;}}
}

@ControllerAdvice

作用于类上，用于标识该类用于处理全局异常。

@ExceptionHandler

作用于方法上，用于对拦截的异常类型进行处理。value 属性用于指定具体的拦截异常类型，如果有多个 ExceptionHandler 存在，则需要指定不同的 value 类型，由于异常类拥有继承关系，所以 ExceptionHandler 会首先执行在继承树中靠前的异常类型。

BindException

该异常来自于表单验证框架 Hibernate validation，当字段验证未通过时会抛出此异常。

编写测试 Controller

@RestController
public class TestController {@RequestMapping(value = "err")public void error(){throw new BusinessException(400, "业务异常错误信息");}@RequestMapping(value = "err2")public void error2(){throw new NullPointerException("手动抛出异常信息");}@RequestMapping(value = "err3")public int error3(){int a = 10 / 0;return a;}
}

使用 AJAX 方式请求时返回的 JSON 格式错误信息。

# /err
{"msg": "应用程序异常","code": -1,"status_code": 0,"data": {"path": "/err","code": 400,"error": "BusinessException","message": "业务异常错误信息","timestamp": "2018-12-18 11:09:00"}
}# /err2
{"msg": "应用程序异常","code": -1,"status_code": 0,"data": {"path": "/err2","code": 500,"error": "NullPointerException","message": "手动抛出异常信息","timestamp": "2018-12-18 11:15:15"}
}# /err3
{"msg": "应用程序异常","code": -1,"status_code": 0,"data": {"path": "/err3","code": 500,"error": "ArithmeticException","message": "/ by zero","timestamp": "2018-12-18 11:15:46"}
}# /err404
{"msg": "应用程序异常","code": -1,"status_code": 0,"data": {"path": "/err404","code": 404,"error": "NoHandlerFoundException","message": "No handler found for GET /err404","timestamp": "2018-12-18 11:16:11"}
}

使用浏览器请求时返回的错误信息界面。

示例代码：https://github.com/BNDong/spring-cloud-examples/tree/master/spring-cloud-zuul/cloud-zuul

参考资料

《微服务分布式架构开发实战》龚鹏著

https://www.jianshu.com/p/1a49fa436623

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