Spring Cloud Gateway 自定义全局异常处理，大厂面试必备常识

在Spring Cloud Gateway中，可以通过定义一个全局过滤器来实现自定义的异常处理。以下是一个简单的示例，展示了如何创建一个全局异常处理器：

import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.core.io.buffer.DataBufferUtils;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;
 
import java.nio.charset.StandardCharsets;
 
public class GlobalExceptionHandlerFilter implements GlobalFilter {
 
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        return chain.filter(exchange).onErrorResume(throwable -> {
            ServerHttpResponse response = exchange.getResponse();
            response.setStatusCode(HttpStatus.INTERNAL_SERVER_ERROR);
            response.getHeaders().setContentType(MediaType.APPLICATION_JSON);
 
            // 自定义错误信息
            String errorMessage = "{\"message\":\"系统异常，请联系管理员\"}";
            byte[] bytes = errorMessage.getBytes(StandardCharsets.UTF_8);
            DataBufferFactory bufferFactory = response.bufferFactory();
            response.setStatusCode(HttpStatus.INTERNAL_SERVER_ERROR);
            response.getHeaders().setContentType(MediaType.APPLICATION_JSON);
            return response.writeWith(Mono.just(bufferFactory.wrap(bytes)));
        });
    }
}

然后需要将这个全局过滤器注册到Spring Cloud Gateway中：

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
 
@Configuration
public class GatewayConfig {
 
    @Bean
    public GlobalExceptionHandlerFilter globalExceptionHandlerFilter() {
        return new GlobalExceptionHandlerFilter();
    }
}

这样配置后，当GatewayFilterChain中的微服务调用出现异常时，Spring Cloud Gateway会使用这个全局过滤器返回自定义的错误信息。