SpringCloudGateway開發(fā)過程解析

更新時間：2019年12月02日 08:27:47 作者：saozhou

這篇文章主要介紹了SpringCloudGateway開發(fā)過程解析,文中通過示例代碼介紹的非常詳細，對大家的學習或者工作具有一定的參考學習價值,需要的朋友可以參考下

路由簡介：

1.SpringCloudGateWay 是用于替代zuul作為API網關，在gateway中有三個重要的名詞：過濾器，斷言，路由

過濾器與斷言是路由的一部分，路由便是將請求進行一系列的處理后分發(fā)到各個服務的一個過程。

路由的過程：首先會加載斷言以及路由，在接受到請求后根據斷言加載的順序會匹配到先加載的斷言，只有與斷言匹配了的請求才會進入路由，沒有匹配到的服務會將請求當成普通的訪問請求。

2：路由加載斷言的方式：

斷言加載的方式有四種，分別是配置文件，java編碼，數據庫以及注冊中心

第一種配置文件：

在官方文檔中主要介紹的就是配置文件的加載方式

官方地址：https://cloud.spring.io/spring-cloud-gateway/reference/html/#gateway-starter

一般的斷言有三種要素：id,uri,predicate.

id是斷言的標識，uri是ip+端口，predicate則是斷言匹配的規(guī)則

3：示例：

新建一個springboot項目，并且引入springcloudgateway的依賴

<dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-gateway</artifactId>
    </dependency>
  </dependencies>

在啟動類注冊三個全局過濾器

@SpringBootApplication
public class GateWayApplication {

  public static void main(String[] args) {
    SpringApplication.run(GateWayApplication.class, args);
  }

  @Bean
  @Order(-1)
  public GlobalFilter a() {
    return (exchange, chain) -> {

      return chain.filter(exchange).then(Mono.fromRunnable(() -> {
        System.out.println(-1);
      }));
    };
  }

  @Bean
  @Order(0)
  public GlobalFilter b() {
    return (exchange, chain) -> {

      return chain.filter(exchange).then(Mono.fromRunnable(() -> {
        System.out.println(0);
      }));
    };
  }

  @Bean
  @Order(1)
  public GlobalFilter c() {
    return (exchange, chain) -> {

      return chain.filter(exchange).then(Mono.fromRunnable(() -> {
        System.out.println(1);
      }));
    };
  }
}

在配置文件類配置兩條路由

server.port: 7777
spring:
 application:
  name: gateway
 cloud:
  gateway:
   discovery:
    locator:
     enabled: true
     lower-case-service-id: true
   routes:
   - id: method_route
    uri: http://127.0.0.1:9999
    predicates:
    - Method=GET
   - id: method_route
    uri: http://127.0.0.1:8006
    predicates:
    - Method=GET

發(fā)送請求，請求到達后匹配的是第一條路由，由此可以知道路由匹配的順序會根據加載的順序來

4：SpringCloudGateWay從注冊中心獲得路由

在官方文檔中，我們可以看到有這樣的一段話

Configuring Predicates and Filters For DiscoveryClient Routes

By default the Gateway defines a single predicate and filter for routes created via a DiscoveryClient.

The default predicate is a path predicate defined with the pattern /serviceId/**, where serviceId is the id of the service from the DiscoveryClient.

The default filter is rewrite path filter with the regex /serviceId/(?<remaining>.*) and the replacement /${remaining}. This just strips the service id from the path before the request is sent downstream.

If you would like to customize the predicates and/or filters used by the DiscoveryClient routes you can do so by setting spring.cloud.gateway.discovery.locator.predicates[x] and spring.cloud.gateway.discovery.locator.filters[y]. When doing so you need to make sure to include the default predicate and filter above, if you want to retain that functionality. Below is an example of what this looks like.

地址：https://cloud.spring.io/spring-cloud-gateway/reference/html/#_global_filters

spring.cloud.gateway.discovery.locator.predicates[0].name: Path
spring.cloud.gateway.discovery.locator.predicates[0].args[pattern]: "'/'+serviceId+'/**'"
spring.cloud.gateway.discovery.locator.predicates[1].name: Host
spring.cloud.gateway.discovery.locator.predicates[1].args[pattern]: "'**.foo.com'"
spring.cloud.gateway.discovery.locator.filters[0].name: Hystrix
spring.cloud.gateway.discovery.locator.filters[0].args[name]: serviceId
spring.cloud.gateway.discovery.locator.filters[1].name: RewritePath
spring.cloud.gateway.discovery.locator.filters[1].args[regexp]: "'/' + serviceId + '/(?<remaining>.*)'"
spring.cloud.gateway.discovery.locator.filters[1].args[replacement]: "'/${remaining}'"

根據文檔介紹，依照這種方式，可以從注冊中心獲得斷言與過濾器的配置

5：SpringGateWay從數據庫配置路由

public class DBRouteDefinitionRepository implements RouteDefinitionRepository

項目中實現了RouteDefinitionRepository后，springgateway會采用你實現的這個類去加載路由，如果不實現則采用他默認的方式加載路由

public class DBRouteDefinitionRepository implements RouteDefinitionRepository {
  //保存路由
  private final Map<String, RouteDefinition> routes = synchronizedMap(new LinkedHashMap<String, RouteDefinition>());
  
  private Logger log = LoggerFactory.getLogger(DBRouteDefinitionRepository.class);
  //初始標準
  private boolean init_flag = true;
  //
  private final GatewayProperties properties;
  private DynamicRouteServiceImpl service;
  

  public DBRouteDefinitionRepository(GatewayProperties properties) {
    this.properties = properties;
    this.service = new DynamicRouteServiceImpl();

  }
  
  @Override
  public Flux<RouteDefinition> getRouteDefinitions() {
    if(init_flag) {
      List<RouteDefinition> routeDefinitions = new ArrayList<>();
      List<RouteDefinition> rs = new ArrayList<>();
      try {
        routeDefinitions = service.quertAllRoutes();//從數據庫中加載route
        rs = this.properties.getRoutes();//獲得配置文件的route
        for (RouteDefinition rse : rs) {
          routeDefinitions.add(rse);
        }
        routes.clear();
        routeDefinitions.forEach(x->routes.put(x.getId(), x));
        init_flag=false;
      } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        log.error("Init Route Fail,Can't get Routes.",e);
      }
      return Flux.fromIterable(routeDefinitions);
    }else {
      return Flux.fromIterable(routes.values());
    }
    
  }

  @Override
  public Mono<Void> delete(Mono<String> routeId) {
    return routeId.flatMap(id -> {
      if (routes.containsKey(id)) {
        routes.remove(id);
        return Mono.empty();
      }
      return Mono.defer(() -> Mono.error(new NotFoundException("RouteDefinition not found: "+routeId)));
    });
  }

  @Override
  public Mono<Void> save(Mono<RouteDefinition> route) {
    return route.flatMap( r -> {
      routes.put(r.getId(), r);
      return Mono.empty();
    });
  }
}

這個是我自己實現的類，這個類可以從數據庫與配置文件中獲得路由配置，從數據庫中獲得路由配置可以根據個人的要求來

@Validated
public class RouteDefinition {

  @NotEmpty
  private String id = UUID.randomUUID().toString();

  @NotEmpty
  @Valid
  private List<PredicateDefinition> predicates = new ArrayList<>();

  @Valid
  private List<FilterDefinition> filters = new ArrayList<>();

  @NotNull
  private URI uri;

  private int order = 0;

  public RouteDefinition() {
  }

  public RouteDefinition(String text) {
    int eqIdx = text.indexOf('=');
    if (eqIdx <= 0) {
      throw new ValidationException("Unable to parse RouteDefinition text '" + text
          + "'" + ", must be of the form name=value");
    }

    setId(text.substring(0, eqIdx));

    String[] args = tokenizeToStringArray(text.substring(eqIdx + 1), ",");

    setUri(URI.create(args[0]));

    for (int i = 1; i < args.length; i++) {
      this.predicates.add(new PredicateDefinition(args[i]));
    }
  }

  public String getId() {
    return id;
  }

  public void setId(String id) {
    this.id = id;
  }

  public List<PredicateDefinition> getPredicates() {
    return predicates;
  }

  public void setPredicates(List<PredicateDefinition> predicates) {
    this.predicates = predicates;
  }

  public List<FilterDefinition> getFilters() {
    return filters;
  }

  public void setFilters(List<FilterDefinition> filters) {
    this.filters = filters;
  }

  public URI getUri() {
    return uri;
  }

  public void setUri(URI uri) {
    this.uri = uri;
  }

  public int getOrder() {
    return order;
  }

  public void setOrder(int order) {
    this.order = order;
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }
    RouteDefinition routeDefinition = (RouteDefinition) o;
    return Objects.equals(id, routeDefinition.id)
        && Objects.equals(predicates, routeDefinition.predicates)
        && Objects.equals(order, routeDefinition.order)
        && Objects.equals(uri, routeDefinition.uri);
  }

  @Override
  public int hashCode() {
    return Objects.hash(id, predicates, uri);
  }

  @Override
  public String toString() {
    return "RouteDefinition{" + "id='" + id + '\'' + ", predicates=" + predicates
        + ", filters=" + filters + ", uri=" + uri + ", order=" + order + '}';
  }

}

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持腳本之家。

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