版本设定 spring cloud 2020.0.2版本
HttpMessageConverters
原因
由于Spring Cloud Gateway 是基于Spring 5、Spring Boot 2.X和Reactor开发的响应式组件，运用了大量的异步实现。
在项目启动过程中，并不会创建HttpMessageConverters实例，具体可查看源码HttpMessageConvertersAutoConfiguration
解决方法
启动时创建相应的Bean,注入到Spring容器
@Configuration
public class FeignConfig {
@Bean
public Decoder decoder(){
return new ResponseEntityDecoder(new SpringDecoder(feignHttpMessageConverter()));
}
private ObjectFactory<HttpMessageConverters> feignHttpMessageConverter(){
HttpMessageConverters httpMessageConverters=new HttpMessageConverters
(new MappingJackson2HttpMessageConverter());
return ()->httpMessageConverters;
}
}
Filter异步调用问题
场景
以鉴权为例，外部访问经由Gateway路由转发，需要验证当前请求中是否存在token，可以通过自定义过滤器实现GlobalFitler实现。
@PropertySource(value = "classpath:loginfilter.properties")
@Component
public class AuthLoginGlobalFilter implements GlobalFilter, Ordered {
@Value("#{'/per-user/login,/goods/**'.split(',')}")
private List<String> ignoreUrls;
@Autowired
private IUserFeign userFeign;
ExecutorService executorService = Executors.newFixedThreadPool(1);
@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
ServerHttpRequest request = exchange.getRequest();
if(ignoreUrls !=null && ignoreUrls.contains(request.getURI().getPath())) {
return chain.filter(exchange);
}
String access_token = request.getHeaders().getFirst("access_token");
if(StringUtils.isBlank(access_token)) {
return onError(exchange,"尚未登录");
}
R<String> r = userFeign.validToken(access_token);
if(r.getCode() == 200) {
ServerHttpRequest serverHttpRequest = request.mutate().header("uid",r.getData()).build();
return chain.filter(exchange.mutate().request(serverHttpRequest).build());
}
return onError(exchange,r.getMsg());
}
@Override
public int getOrder() {
return 0;
}
private Mono<Void> onError(ServerWebExchange exchange,String msg) {
ServerHttpResponse response = exchange.getResponse();
response.setStatusCode(HttpStatus.UNAUTHORIZED);
response.getHeaders().add("Content-Type","application/json;charset=UTF-8");
R r = new R.Builder().buildCustomize(HttpStatus.UNAUTHORIZED.value(),msg);
ObjectMapper objectMapper = new ObjectMapper();
String rs = "";
try {
rs = objectMapper.writeValueAsString(r);
} catch (JsonProcessingException e) {
e.printStackTrace();
}
DataBuffer dataBuffer =response.bufferFactory().wrap(rs.getBytes());
return response.writeWith(Flux.just(dataBuffer));
}
}
R r = userFeign.validToken(access_token);属于同步调用，会报以下错误：
错误原因
在BlockingSingleSubscriber中会进行判断：
final T blockingGet() {
if (Schedulers.isInNonBlockingThread()) {
throw new IllegalStateException("block()/blockFirst()/blockLast() are blocking, which is not supported in thread " + Thread.currentThread().getName());
}
if (getCount() != 0) {
try {
await();
}
catch (InterruptedException ex) {
dispose();
throw Exceptions.propagate(ex);
}
}
Throwable e = error;
if (e != null) {
RuntimeException re = Exceptions.propagate(e);
//this is ok, as re is always a new non-singleton instance
re.addSuppressed(new Exception("#block terminated with an error"));
throw re;
}
return value;
}
解决方案
解决方案，同步转异步，如果需要获取返回结果，可以通过Future方式获取
@PropertySource(value = "classpath:loginfilter.properties")
@Component
public class AuthLoginGlobalFilter implements GlobalFilter, Ordered {
@Value("#{'/per-user/login,/goods/**'.split(',')}")
private List<String> ignoreUrls;
@Autowired
private IUserFeign userFeign;
ExecutorService executorService = Executors.newFixedThreadPool(1);
@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
ServerHttpRequest request = exchange.getRequest();
if(ignoreUrls !=null && ignoreUrls.contains(request.getURI().getPath())) {
return chain.filter(exchange);
}
String access_token = request.getHeaders().getFirst("access_token");
if(StringUtils.isBlank(access_token)) {
return onError(exchange,"尚未登录");
}
// WebFlux异步调用，同步会报错
Future future = executorService.submit((Callable<R>) () -> userFeign.validToken(access_token));
R<String> r = null;
try {
r = (R<String>) future.get();
if(r.getCode() == 200) {
ServerHttpRequest serverHttpRequest = request.mutate().header("uid",r.getData()).build();
return chain.filter(exchange.mutate().request(serverHttpRequest).build());
}
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
return onError(exchange,r.getMsg());
}
@Override
public int getOrder() {
return 0;
}
private Mono<Void> onError(ServerWebExchange exchange,String msg) {
ServerHttpResponse response = exchange.getResponse();
response.setStatusCode(HttpStatus.UNAUTHORIZED);
response.getHeaders().add("Content-Type","application/json;charset=UTF-8");
R r = new R.Builder().buildCustomize(HttpStatus.UNAUTHORIZED.value(),msg);
ObjectMapper objectMapper = new ObjectMapper();
String rs = "";
try {
rs = objectMapper.writeValueAsString(r);
} catch (JsonProcessingException e) {
e.printStackTrace();
}
DataBuffer dataBuffer =response.bufferFactory().wrap(rs.getBytes());
return response.writeWith(Flux.just(dataBuffer));
}
}
总结
以上为个人经验，希望能给大家一个参考，也希望大家多多支持编程网。
