spring cloud gateway使用详解

@Component
public class LoginFilter implements GlobalFilter, Ordered {

  /**
    * 执行过滤器中的业务逻辑
    */
  @Override
  public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
    System.out.println("执行了自定义的全局过滤器");
    //1.获取请求参数access-token
    String token = exchange.getRequest().getQueryParams().getFirst("access-token");
    //2.判断是否存在
    if(token == null) {
      //3.如果不存在 : 认证失败
      System.out.println("没有登录");
      exchange.getResponse().setStatusCode(HttpStatus.UNAUTHORIZED);
      return exchange.getResponse().setComplete(); //请求结束
    }
    //4.如果存在,继续执行
    return chain.filter(exchange); //继续向下执行
  }

  /**
    * 指定过滤器的执行顺序 , 返回值越小执行优先级越高
    */
  @Override
  public int getOrder() {
    return Ordered.HIGHEST_PRECEDENCE;
  }
}

/**
 * 实际业务处理
 */
public class JsonErrorWebExceptionHandler extends DefaultErrorWebExceptionHandler {

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

  @Override
  protected Map<String, Object> getErrorAttributes(ServerRequest request, boolean includeStackTrace) {
    // 这里可以根据异常类型进行定制化逻辑
    Throwable error = super.getError(request);
    Map<String, Object> errorAttributes = new HashMap<>(8);
    errorAttributes.put("message", error.getMessage());
    errorAttributes.put("code", HttpStatus.INTERNAL_SERVER_ERROR.value());
    errorAttributes.put("method", request.methodName());
    errorAttributes.put("path", request.path());
    if(error instanceof ResponseStatusException){
      ResponseStatusException statusException = (ResponseStatusException) error;
      errorAttributes.put("code", statusException.getStatus().value());
    }
    return errorAttributes;
  }

  @Override
  protected RouterFunction<ServerResponse> getRoutingFunction(ErrorAttributes errorAttributes) {
    return RouterFunctions.route(RequestPredicates.all(), this::renderErrorResponse);
  }

  @Override
  protected int getHttpStatus(Map<String, Object> errorAttributes) {
    // 这里其实可以根据errorAttributes里面的属性定制HTTP响应码
    return (int)errorAttributes.get("code");
  }
}



/**
 * 自定义异常处理
 */
@Configuration
@EnableConfigurationProperties({ ServerProperties.class, ResourceProperties.class })
public class ExceptionHandlerConfiguration {

  private final ServerProperties serverProperties;

  private final ApplicationContext applicationContext;

  private final ResourceProperties resourceProperties;

  private final List<ViewResolver> viewResolvers;

  private final ServerCodecConfigurer serverCodecConfigurer;

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

  // 实例化逻辑错误处理类
  @Bean
  @Order(Ordered.HIGHEST_PRECEDENCE)
  public ErrorWebExceptionHandler errorWebExceptionHandler(ErrorAttributes errorAttributes) {
    JsonErrorWebExceptionHandler exceptionHandler = new JsonErrorWebExceptionHandler(errorAttributes, this.resourceProperties,
                                                                                     this.serverProperties.getError(), this.applicationContext);
    exceptionHandler.setViewResolvers(this.viewResolvers);
    exceptionHandler.setMessageWriters(this.serverCodecConfigurer.getWriters());
    exceptionHandler.setMessageReaders(this.serverCodecConfigurer.getReaders());
    return exceptionHandler;
  }
}

@Configuration
public class GwCorsFilter {

  @Bean
  public CorsWebFilter corsFilter() {
    CorsConfiguration config = new CorsConfiguration();
    config.setAllowCredentials(true);   // 允许cookies跨域
    config.addAllowedOrigin("*");       // #允许向该服务器提交请求的URI，*表示全部允许
    config.addAllowedHeader("*");       // #允许访问的头信息,*表示全部
    config.addAllowedMethod("*");       // 允许提交请求的方法类型，*表示全部允许
    config.setMaxAge(18000L);           // 预检请求的缓存时间（秒），即在这个时间段里，对于相同的跨域请求不会再预检了
    UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource(new PathPatternParser());
    source.registerCorsConfiguration("/**", config);
    return new CorsWebFilter(source);
  }
}