Spring Cloud Gateway 全局异常处理

统一异常捕获，并 格式化为{"code": "", "message": ""} 的JSON字符串返回给Gateway上游服务。

范例

示例：修改前抛出一个运行时异常

{
  "timestamp": "2019-03-12T05:34:05.356+0000",
  "path": "/app/insertCompany",
  "status": 500,
  "error": "Internal Server Error",
  "message": "发生错误！"
}

示例：全局异常处理抛出一个运行时异常

{
  "code": 500,
  "message": "Internal Server Error"
}

如何添加

自定义异常处理配置

@Configuration
public class ExceptionConfig {

    /**
     * 自定义异常处理[@@]注册Bean时依赖的Bean，会从容器中直接获取，所以直接注入即可
     */
    @Primary
    @Bean
    @Order(Ordered.HIGHEST_PRECEDENCE)
    public ErrorWebExceptionHandler errorWebExceptionHandler(ObjectProvider<List<ViewResolver>> viewResolversProvider,
                                                             ServerCodecConfigurer serverCodecConfigurer) {
        JsonExceptionHandler jsonExceptionHandler = new JsonExceptionHandler();
        jsonExceptionHandler.setViewResolvers(viewResolversProvider.getIfAvailable(Collections::emptyList));
        jsonExceptionHandler.setMessageWriters(serverCodecConfigurer.getWriters());
        jsonExceptionHandler.setMessageReaders(serverCodecConfigurer.getReaders());
        return jsonExceptionHandler;
    }

}

全局异常处理监听器

public class JsonExceptionHandler implements ErrorWebExceptionHandler {

    private static final Logger log = LoggerFactory.getLogger(JsonExceptionHandler.class);

    /**
     * MessageReader
     */
    private List<HttpMessageReader<?>> messageReaders = Collections.emptyList();

    /**
     * MessageWriter
     */
    private List<HttpMessageWriter<?>> messageWriters = Collections.emptyList();

    /**
     * ViewResolvers
     */
    private List<ViewResolver> viewResolvers = Collections.emptyList();

    /**
     * 存储处理异常后的信息
     */
    private ThreadLocal<Map<String, Object>> exceptionHandlerResult = new ThreadLocal<>();

    /**
     * 参考AbstractErrorWebExceptionHandler
     */
    public void setMessageReaders(List<HttpMessageReader<?>> messageReaders) {
        Assert.notNull(messageReaders, "'messageReaders' must not be null");
        this.messageReaders = messageReaders;
    }

    /**
     * 参考AbstractErrorWebExceptionHandler
     */
    public void setViewResolvers(List<ViewResolver> viewResolvers) {
        this.viewResolvers = viewResolvers;
    }

    /**
     * 参考AbstractErrorWebExceptionHandler
     */
    public void setMessageWriters(List<HttpMessageWriter<?>> messageWriters) {
        Assert.notNull(messageWriters, "'messageWriters' must not be null");
        this.messageWriters = messageWriters;
    }

    @Override
    public Mono<Void> handle(ServerWebExchange exchange, Throwable ex) {
        // 按照异常类型进行处理
        HttpStatus httpStatus;
        String body;
        if (ex instanceof NotFoundException) {
            httpStatus = HttpStatus.NOT_FOUND;
            body = "Service Not Found";
        } else if (ex instanceof ResponseStatusException) {
            ResponseStatusException responseStatusException = (ResponseStatusException) ex;
            httpStatus = responseStatusException.getStatus();
            body = responseStatusException.getMessage();
        } else {
            httpStatus = HttpStatus.INTERNAL_SERVER_ERROR;
            body = "Internal Server Error";
        }
        //封装响应体,此body可修改为自己的jsonBody
        Map<String, Object> result = new HashMap<>(2, 1);
        result.put("httpStatus", httpStatus);

        String msg = "{\"code\":" + httpStatus + ",\"message\": \"" + body + "\"}";
        result.put("body", msg);
        //错误记录
        ServerHttpRequest request = exchange.getRequest();
        log.error("[全局异常处理]异常请求路径:{},记录异常信息:{}", request.getPath(), ex.getMessage());
        //参考AbstractErrorWebExceptionHandler
        if (exchange.getResponse().isCommitted()) {
            return Mono.error(ex);
        }
        exceptionHandlerResult.set(result);
        ServerRequest newRequest = ServerRequest.create(exchange, this.messageReaders);
        return RouterFunctions.route(RequestPredicates.all(), this::renderErrorResponse).route(newRequest)
                .switchIfEmpty(Mono.error(ex))
                .flatMap((handler) -> handler.handle(newRequest))
                .flatMap((response) -> write(exchange, response));

    }

    /**
     * 参考DefaultErrorWebExceptionHandler
     */
    protected Mono<ServerResponse> renderErrorResponse(ServerRequest request) {
        Map<String, Object> result = exceptionHandlerResult.get();
        return ServerResponse.status((HttpStatus) result.get("httpStatus"))
                .contentType(MediaType.APPLICATION_JSON_UTF8)
                .body(BodyInserters.fromObject(result.get("body")));
    }

    /**
     * 参考AbstractErrorWebExceptionHandler
     */
    private Mono<? extends Void> write(ServerWebExchange exchange,
                                       ServerResponse response) {
        exchange.getResponse().getHeaders()
                .setContentType(response.headers().getContentType());
        return response.writeTo(exchange, new ResponseContext());
    }

    /**
     * 参考AbstractErrorWebExceptionHandler
     */
    private class ResponseContext implements ServerResponse.Context {

        @Override
        public List<HttpMessageWriter<?>> messageWriters() {
            return JsonExceptionHandler.this.messageWriters;
        }

        @Override
        public List<ViewResolver> viewResolvers() {
            return JsonExceptionHandler.this.viewResolvers;
        }
    }
}

总结

这两个文件就可以满足我们Gateway全局监听的需求，当在Gateway发生错误时，会进行拦截并格式化信息，返回给客户端。