SpringCloud中如何使用Zuul路由网关，相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。
网关可以将所有的api统一暴露，保护其他服务api接口和信息，以防止被外界直接调用
网关可以做身份认证和权限认证，防止非法请求操作API，保护服务
网关可以实现监控功能，实时日志输出，对请求进行记录
网关可以实现流量监控，便于在高流量情况下对服务进行降级
Zuul可以和Ribbon、Eureka相结合，实现智能路由和负载均衡
通过一定策略，把请求流量分发到集群状态的多个实例中
可以将API从内部接口中分离出来，方便单测
Zuul基于Servlet实现，通过自定义的ZuulServlet来对请求进行控制，Zuul中有一系列的过滤器，这些过滤器是同样是Zuul的实现关键，请求发起和响应期间，通过这些过滤器实现Zuul的功能。具体有以下四个：
PRE过滤器：在请求路由到具体的服务之前执行，用途：安全验证（身份校验，参数校验、ip黑白名单）；
ROUTING过滤器 ：在请求的服务到具体的微服务实例时执行，用途：进行网络请求（默认使用HttpClient）；
POST过滤器：在请求路由到微服务之后执行，用途：统计信息，回传响应；
ERROR过滤器：在其他过滤器发生错误的时候执行，用途：保证请求能够正确响应；
ZuulFilter中的方法有以下四个，继承ZuulFilter并且重写以下四个方法即可实现一个过滤器。
public String filterType(); 返回该Filter的类型，即如上四种过滤器。
public int filterOrder(); 返回该过滤器的执行顺序。
public boolean shouldFilter(); 返回该过滤器是否需要执行。
public Object run(); 执行具体的过滤逻辑。
ZuulServlet是Zuul的核心Servlet，负责初始化ZuulFilter并且编排这些过滤器，具体代码在service()方法中。
public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
try {
this.init((HttpServletRequest)servletRequest, (HttpServletResponse)servletResponse);
RequestContext context = RequestContext.getCurrentContext();
context.setZuulEngineRan();
try {
this.preRoute();
} catch (ZuulException var13) {
this.error(var13);
this.postRoute();
return;
}
try {
this.route();
} catch (ZuulException var12) {
this.error(var12);
this.postRoute();
return;
}
try {
this.postRoute();
} catch (ZuulException var11) {
this.error(var11);
}
} catch (Throwable var14) {
this.error(new ZuulException(var14, 500, "UNHANDLED_EXCEPTION_" + var14.getClass().getName()));
} finally {
RequestContext.getCurrentContext().unset();
}
}
RequestContext是ZuulFilter中负责上下文衔接的角色，其本身是一个ConcurrentHashMap,包含Request和Response、routeType、routeHost等上下文需要的对象。
父级项目zuul-test/pom.xml
<groupId>com.calvin.zuul</groupId> <artifactId>zuul-test</artifactId> <packaging>pom</packaging> <version>1.0-SNAPSHOT</version> <modules> <module>eureka-server</module> <module>user-service</module> <module>zuul-service</module> </modules> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.3.RELEASE</version> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-dependencies</artifactId> <version>Dalston.SR4</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement>
zuul-service/pom.xml
<parent> <artifactId>zuul-test</artifactId> <groupId>com.calvin.zuul</groupId> <version>1.0-SNAPSHOT</version> </parent> <modelVersion>4.0.0</modelVersion> <artifactId>zuul-service</artifactId> <dependencies> <!-- Springboot支持--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <!--SpringCloud支持 --> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-eureka</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-zuul</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build>
zuul-service/ZuulApplication.java
/**
* <p>
* 启动类
* </p>
* @author Calvin
* @date 2019/10/25
* @since 1.0
*/
@SpringBootApplication
@EnableEurekaClient
@EnableZuulProxy
public class ZuulServerApplication {
public static void main(String[] args) {
SpringApplication.run(ZuulServerApplication.class, args);
}
}zuul-service/application.yml
spring: application: name: zuul-service server: port: 8030 eureka: client: service-url: defaultZone: http://localhost:8010/eureka/ instance: hostname: localhost zuul: routes: user-api: path: /user/** serviceId: user-service
user-service/pom.xml
<parent> <artifactId>zuul-test</artifactId> <groupId>com.calvin.zuul</groupId> <version>1.0-SNAPSHOT</version> </parent> <modelVersion>4.0.0</modelVersion> <artifactId>user-service</artifactId> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-eureka</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-feign</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build>
user-service/application.yml
spring: application: name: user-service server: port: 8020 eureka: client: service-url: defaultZone: http://localhost:8010/eureka/ instance: hostname: localhost
user-service/UserApplication.java
/**
* <p>
* 启动类
* </p>
* @author Calvin
* @date 2019/10/25
* @since 1.0
*/
@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
public class UserApplication {
public static void main(String[] args) {
SpringApplication.run(UserApplication.class, args);
}
}user-service/controller/UserController.java
/**
* <p> </p>
*
* @author Calvin
* @date 2019/10/25
* @since
*/
@RestController
public class UserController {
/**
* 简单构建一个User
*/
@GetMapping("/userDetail/{userId}")
public SysUser getUserDetail(@PathVariable("userId") String userId){
SysUser sysUser = new SysUser();
sysUser.setId(userId);
sysUser.setAge(20);
sysUser.setPassword(MD5Utils.digestAsHex("123456"));
sysUser.setUsername("Calvin");
//图片来自百度
sysUser.setHeadImg("https://b-ssl.duitang.com/uploads/item/201510/17/20151017181645_c5hWE.thumb.700_0.jpeg");
return sysUser;
}
}依次启动eureka-server, user-server, zuul-server
浏览器调用 http://localhost:8030/user/userDetail/1
从调用结果中可以看到我们从zuul-service中调用了user-service的方法，并且调用成功。从而证明路由配置可用；
如需配置版本号，我们只需要咱zuul-service/application.yml中添加配置：zuul.prefix=v1
如果需要在Zuul中实现服务熔断，只需要实现ZuulFallbackProvider接口，重写其中两个方法，通过getRoute()方法返回我们需要熔断的路由，通过fallbackResponse()方法来重写熔断时执行的逻辑。
如下，我们实现第一个user-service的熔断器
/**
* <p>
* user-service熔断器
* </p>
*
* @author Calvin
* @date 2019/10/27
* @since
*/
@Component
public class UserServiceCallback implements ZuulFallbackProvider {
@Override
public String getRoute() {
return "user-service";
}
@Override
public ClientHttpResponse fallbackResponse() {
return new CommonClientResponse();
}
}贴上CommonClientResponse的代码，就是针对ClientHttpResponse接口的封装
/**
* <p>封装的通用返回类 </p>
*
* @author Calvin
* @date 2019/10/27
* @since
*/
public class CommonClientResponse implements ClientHttpResponse {
@Override
public HttpStatus getStatusCode() throws IOException {
return HttpStatus.OK;
}
@Override
public int getRawStatusCode() throws IOException {
return 0;
}
@Override
public String getStatusText() throws IOException {
return "success";
}
@Override
public void close() {
}
@Override
public InputStream getBody() throws IOException {
return new ByteArrayInputStream("hello , this is zuul fallback".getBytes());
}
@Override
public HttpHeaders getHeaders() {
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
return headers;
}
}接下来做个测试，我们停掉user-service服务，然后再访问 http://localhost:8030/user/userDetail/1 
结果当然是我们定义的熔断器中返回的内容了！
如果需要对其他服务使用同一个熔断器，只需要在
getRoute()方法中返回通配符return "*"就可以了
ZuulFilter是Zuul实现过滤和网关的关键，此类有四个枚举值，分别代表Zuul中的过滤器类型。如果需要实现过滤，只需要继承ZuulFilter，并且指定其过滤器类型，枚举值为：
/**
* {@link ZuulFilter#filterType()} error type.
*/
String ERROR_TYPE = "error";
/**
* {@link ZuulFilter#filterType()} post type.
*/
String POST_TYPE = "post";
/**
* {@link ZuulFilter#filterType()} pre type.
*/
String PRE_TYPE = "pre";
/**
* {@link ZuulFilter#filterType()} route type.
*/
String ROUTE_TYPE = "route";简单实现一个过滤器
/**
* <p> header过滤器 </p>
*
* @author Calvin
* @date 2019/10/27
* @since
*/
@Component
public class TokenFilter extends ZuulFilter {
private static final Logger logger = LoggerFactory.getLogger(TokenFilter.class);
@Override
public String filterType() {
return PRE_TYPE;
}
@Override
public int filterOrder() {
return 0;
}
@Override
public boolean shouldFilter() {
return true;
}
@Override
public Object run() {
RequestContext requestContext = RequestContext.getCurrentContext();
HttpServletRequest request = requestContext.getRequest();
logger.info("request_url : {}, request_headers: {}",request.getRequestURI(), JSON.toJSON(request.getHeaderNames()).toString());
return null;
}
}重新启动zuul-service，调用服务控制台已经可以输出如下内容：
2019-11-12 22:04:36.726 INFO 58984 --- [nio-8030-exec-4] com.calvin.zuul.filter.TokenFilter : request_url : /user/userDetail/1, request_headers: ["host","connection","cache-control","upgrade-insecure-requests","user-agent","sec-fetch-user","accept","sec-fetch-site","sec-fetch-mode","accept-encoding","accept-language","cookie"]
若需要拦截请求，或者设置白名单等，在RequestContext中设置好自己的statusCode等，就可以了
requestContext.setSendZuulResponse(false);
requestContext.setResponseStatusCode(401);
ctx.getResponse().getWriter().write("there is no token found,please relogin!")看完上述内容，你们掌握SpringCloud中如何使用Zuul路由网关的方法了吗？如果还想学到更多技能或想了解更多相关内容，欢迎关注亿速云行业资讯频道，感谢各位的阅读！
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