Spring Cloud 实战 (三) 服务网关 gateway

在Spring Cloud (二) 服务的注册与发现的基础上 创建一个名为SpringCloud-gateway的项目
在 Maven 中 添加依赖：

		
            org.springframework.cloud
            spring-cloud-starter-gateway
        
        
            org.springframework.boot
            spring-boot-starter-webflux
        
        
            org.springframework.cloud
            spring-cloud-starter-netflix-hystrix
        
        
            org.springframework.cloud
            spring-cloud-starter-netflix-eureka-client
        
		
		
        
            
                org.springframework.cloud
                spring-cloud-dependencies
                Greenwich.RELEASE
                pom
                import
                
                
            
        
    

然后修改配置文件：

server:
  port: 8080
  
spring:
  application:
    name: gateway
  cloud:
    gateway:
      discovery:
        locator:
          enabled: true #表示是否与服务发现组件（register）进行结合，通过serviceId（必须设置成大写）转发到具体的服务实例 默认：false
          
logging:
  level:
    org.springframework.cloud.gateway: trace
    org.springframework.http.server.reactive: debug
    org.springframework.web.reactive: debug
    reactor.ipc.netty: debug
    
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

创建服务拦截：
新建一个类ApiGlobalFilter并继承GlobalFilter：

import org.apache.commons.lang.StringUtils;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.http.HttpStatus;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

import java.nio.charset.StandardCharsets;
import java.util.HashMap;
import java.util.Map;

@Component
public class ApiGlobalFilter implements GlobalFilter {

    @Override
    public Mono filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        String token = exchange.getRequest().getQueryParams().getFirst("token");
        if (StringUtils.isBlank(token)) {//验证token值
            ServerHttpResponse response = exchange.getResponse();
            Map message = new HashMap<>();
            message.put("code", 5001);
            message.put("message", "鉴权失败，无token值");
            byte[] bits = message.toString().getBytes(StandardCharsets.UTF_8);
            DataBuffer buffer = response.bufferFactory().wrap(bits);
            response.setStatusCode(HttpStatus.UNAUTHORIZED);
            response.getHeaders().add("Content-Type", "text/json;charset=UTF-8");
            return response.writeWith(Mono.just(buffer));
        }
        return chain.filter(exchange);
    }
}

然后访问http://localhost:8080/SPRINGCLOUD-CLIENT-A/hello/index
效果图：

添加错误拦截：(友好提示)
新建一个类JsonExceptionHandler并且继承DefaultErrorWebExceptionHandler类：

import org.springframework.boot.autoconfigure.web.ErrorProperties;
import org.springframework.boot.autoconfigure.web.ResourceProperties;
import org.springframework.boot.autoconfigure.web.reactive.error.DefaultErrorWebExceptionHandler;
import org.springframework.boot.web.reactive.error.ErrorAttributes;
import org.springframework.context.ApplicationContext;
import org.springframework.http.HttpStatus;
import org.springframework.web.reactive.function.server.*;

import java.util.HashMap;
import java.util.Map;

/** 
* @author  作者 : 小布
* @version 创建时间 : 2019年5月8日 上午10:22:23 
* @explain 类说明 : 自定义异常处理 返回统一的 JSON 格式
*/
public class JsonExceptionHandler extends DefaultErrorWebExceptionHandler {

    public JsonExceptionHandler(ErrorAttributes errorAttributes, ResourceProperties resourceProperties,
                                ErrorProperties errorProperties, ApplicationContext applicationContext) {
        super(errorAttributes, resourceProperties, errorProperties, applicationContext);
    }

    /**
     * 获取异常属性
     */
    @Override
    protected Map getErrorAttributes(ServerRequest request, boolean includeStackTrace) {
        int code = 500;
        Throwable error = super.getError(request);
        if (error instanceof org.springframework.cloud.gateway.support.NotFoundException) {
            code = 404;
        }
        return response(code, this.buildMessage(request, error));
    }

    /**
     * 指定响应处理方法为 JSON 处理的方法
     * @param errorAttributes
     */
    @Override
    protected RouterFunction getRoutingFunction(ErrorAttributes errorAttributes) {
        return RouterFunctions.route(RequestPredicates.all(), this::renderErrorResponse);
    }

    /**
     * 根据 code 获取对应的 HttpStatus
     * @param errorAttributes
     */
    @Override
    protected HttpStatus getHttpStatus(Map errorAttributes) {
        int statusCode = (int) errorAttributes.get("code");
        return HttpStatus.valueOf(statusCode);
    }

    /**
     * 构建异常信息
     * @param request
     * @param ex
     * @return
     */
    private String buildMessage(ServerRequest request, Throwable ex) {
        StringBuilder message = new StringBuilder("Failed to handle request [");
        message.append(request.methodName());
        message.append(" ");
        message.append(request.uri());
        message.append("]");
        if (ex != null) {
            message.append(": ");
            message.append(ex.getMessage());
        }
        return message.toString();
    }

    /**
     * 构建返回的 JSON 数据格式
     * @param status        状态码
     * @param errorMessage  异常信息
     * @return
     */
    public static Map response(int status, String errorMessage) {
        Map map = new HashMap<>();
        map.put("code", status);
        map.put("message", errorMessage);
        return map;
    }

}

需要添加以下配置类：

import org.springframework.beans.factory.ObjectProvider;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.boot.autoconfigure.web.ResourceProperties;
import org.springframework.boot.autoconfigure.web.ServerProperties;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.boot.web.reactive.error.ErrorAttributes;
import org.springframework.boot.web.reactive.error.ErrorWebExceptionHandler;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;
import org.springframework.http.codec.ServerCodecConfigurer;
import org.springframework.web.reactive.result.view.ViewResolver;

import com.springcloud.exception.JsonExceptionHandler;

import java.util.Collections;
import java.util.List;
/** 
* @author  作者 : 小布
* @version 创建时间 : 2019年5月8日 上午10:24:00 
* @explain 类说明 : JsonExceptionHandler加载到Spring容器中的配置类
*/
@SpringBootConfiguration
@EnableConfigurationProperties({ServerProperties.class, ResourceProperties.class})
public class ErrorHandlerConfiguration {

    private final ServerProperties serverProperties;

    private final ApplicationContext applicationContext;

    private final ResourceProperties resourceProperties;

    private final List viewResolvers;

    private final ServerCodecConfigurer serverCodecConfigurer;

    public ErrorHandlerConfiguration(ServerProperties serverProperties,
                                     ResourceProperties resourceProperties,
                                     ObjectProvider> viewResolversProvider,
                                     ServerCodecConfigurer serverCodecConfigurer,
                                     ApplicationContext applicationContext) {
        this.serverProperties = serverProperties;
        this.applicationContext = applicationContext;
        this.resourceProperties = resourceProperties;
        this.viewResolvers = viewResolversProvider.getIfAvailable(Collections::emptyList);
        this.serverCodecConfigurer = serverCodecConfigurer;
    }

    /**
     * gateway 启动时执行此方法，将 JsonExceptionHandler 注入到 Spring 容器中
     * 以便发生异常时执行自定义的 JsonExceptionHandler
     * @param errorAttributes
     * @return
     */
    @Bean
    @Order(Ordered.HIGHEST_PRECEDENCE)
    public ErrorWebExceptionHandler errorWebExceptionHandler(ErrorAttributes errorAttributes) {
        JsonExceptionHandler exceptionHandler = new JsonExceptionHandler(
                errorAttributes,
                this.resourceProperties,
                this.serverProperties.getError(),
                this.applicationContext);
        exceptionHandler.setViewResolvers(this.viewResolvers);
        exceptionHandler.setMessageWriters(this.serverCodecConfigurer.getWriters());
        exceptionHandler.setMessageReaders(this.serverCodecConfigurer.getReaders());
        return exceptionHandler;
    }
}

效果图：

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