框架中的自定义网关
背景：
有些公司项目中使用了自建的项目框架，网关进行了一些自定义的实现。如何实现一个自定义网关，又有哪些作用呢？本文将进行一些浅显的说明。
搭建一个项目 hand-gateway，并注册到 nacos 注册中心
项目依赖
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId></dependency>
<dependency> <groupId>com.alibaba.cloud</groupId> <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId></dependency>
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配置路由转发拦截器 RouteInterceptor
路由映射可以从配置文件、配置中心或者数据库中进行加载，然后做映射转换，然后通过 RestTemplate 进行转发，restTemplate 通过 loadblance 可以实现负载均衡。下面代码实现了 Post、get 的方法请求，json 请求暂未实现，感兴趣的可以试下。
@Slf4j@Componentpublic class RouteInterceptor implements HandlerInterceptor {
@Autowired private RestTemplate restTemplate; @Autowired private DiscoveryClient discoveryClient;
@Override public boolean preHandle (HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { HttpHeaders httpHeaders = new HttpHeaders(); String requestUrl = request.getRequestURI(); if(StrUtil.isNotEmpty(request.getQueryString())){ String query = URLDecoder.decode(request.getQueryString(),"UTF-8"); requestUrl =requestUrl+"?"+query; } log.info("requestUrl {}",requestUrl); // 注册中心获取注册的服务// List<ServiceInstance> instances = discoveryClient.getInstances("paw-dogs-sky-service");// String ipAddr = instances.get(0).getUri().toString(); // 加载路由映射 如配置文件、配置中心、redis、数据库 Map<String,String> routerMap = new HashMap<>(16); routerMap.put("/sky-api","paw-dogs-sky-service"); String routerKey = requestUrl; if(requestUrl.indexOf("/",1)>0){ routerKey = requestUrl.substring(0,requestUrl.indexOf("/",1)); } if(routerMap.containsKey(routerKey)){ String serverName = routerMap.get(routerKey); // 做地址映射 String targetUrl = "http://"+requestUrl.replaceFirst(routerKey,serverName);
log.info("requestUrl {} ==> targetUrl {}",requestUrl, targetUrl);
ResponseEntity<String> responseEntity; if("POST".equalsIgnoreCase(request.getMethod())){ MultiValueMap<String, String> params = new LinkedMultiValueMap<>(); Map<String, String[]> paramMap = request.getParameterMap(); for (String paramName: paramMap.keySet()) { params.addAll(paramName, Arrays.asList(paramMap.get(paramName))); } httpHeaders.setContentType(MediaType.APPLICATION_FORM_URLENCODED); HttpEntity<Object> requestEntity = new HttpEntity<>(params, httpHeaders); responseEntity = restTemplate.postForEntity(targetUrl, requestEntity, String.class); }else{ responseEntity = restTemplate.getForEntity(targetUrl, String.class); }
try { response.setStatus(responseEntity.getStatusCodeValue()); String responseBody = responseEntity.getBody(); response.setContentType("application/json;charset=UTF-8"); PrintWriter out = response.getWriter(); out.print(responseBody); out.flush(); out.close(); } catch (IOException e) { e.printStackTrace(); }
return false; } return true; }
@Override public void postHandle (HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { HandlerInterceptor.super.postHandle(request, response, handler, modelAndView); }
@Override public void afterCompletion (HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { HandlerInterceptor.super.afterCompletion(request, response, handler, ex); }}
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增加权限校验拦截器 TokenInterceptor，获取 token 后根据验证方式 jwt 或者 redis 的方式进行权限校验，并将用户的一些信息放入到 header 中，往下传播。
@Slf4j@Componentpublic class TokenInterceptor implements HandlerInterceptor {
public static final String TOKEN_NAME = "token";
@Override public boolean preHandle (HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { log.info("TokenInterceptor requestUrl "+request.getRequestURI()); String token = request.getHeader(TOKEN_NAME); if(StrUtil.isEmpty(token)){ token = request.getParameter(TOKEN_NAME); } // 校验token jwt 或者 redis 此处省略 if(StrUtil.isNotEmpty(token)){ return true; }
try { response.setStatus(HttpStatus.UNAUTHORIZED.value()); response.setContentType("application/json;charset=UTF-8"); PrintWriter out = response.getWriter(); out.print(HttpStatus.UNAUTHORIZED.getReasonPhrase()); out.flush(); out.close(); } catch (IOException e) { e.printStackTrace(); } return false; }}
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配置服务，RestTemplate 添加 @LoadBalanced 注解进行负载均衡，添加拦截器，注意添加的顺序。
@Configurationpublic class WebConfiguration implements WebMvcConfigurer {
@Autowired private TokenInterceptor tokenInterceptor;
@Autowired private RouteInterceptor routeInterceptor;
@Bean @LoadBalanced @ConditionalOnClass(RestTemplate.class) public RestTemplate restTemplate(){ return new RestTemplate(); }
@Override public void addInterceptors(InterceptorRegistry registry) { registry.addInterceptor(tokenInterceptor).addPathPatterns("/**").excludePathPatterns("/anonymous/**"); registry.addInterceptor(routeInterceptor).addPathPatterns("/**");
}
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至此简单的网关项目完成。
搭建应用服务 sky-service，并注册到 nacos 注册中心
服务名称
spring: application: name: paw-dogs-sky-service
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服务接口，增加 port 查看负载均衡，示例实现了 get post 方法
@RestControllerpublic class SkyController {
@Value("${spring.application.name:sky-service}") private String applicationName;
@Value("${server.port:8080}") private Integer serverPort;
@GetMapping("/sky") public String sky (@RequestParam(required = false) String name) { String msg = "this is " + applicationName + " port " + serverPort + " Time: " + DateUtil.now(); if (StrUtil.isNotEmpty(name)) { msg = msg + " name: " + name; } return msg; }
@PostMapping("/deliver") public String deliver (String packageBox) { String msg = "this is " + applicationName + " port " + serverPort + " Time: " + DateUtil.now(); return msg + " delivered packageBox: " + packageBox; }
}
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通过 idea 的方式设置不同的端口启动两个服务，VM options 设置 -Dserver.port=8081
通过 postman 访问网关项目，header 携带 token
http://127.0.0.1:8080/sky-api/sky?name=fly
返回结果
this is paw-dogs-sky-service port 8082 Time: 2021-06-17 16: 45: 05 name: fly
访问 Post 请求，header 携带 token，form-urlencoded 参数 packageBox=cake
http://127.0.0.1:8080/sky-api/deliver
返回结果
this is paw-dogs-sky-service port 8082 Time: 2021-06-17 16: 11: 23 delivered packageBox: cake
多访问几次会发现 port 端口在 8081 8082 切换，负载均衡实现。
至此一个自定义网关项目雏形完成，可以根据项目实际需要自定义其他内容，增加拦截器来实现不同的业务，如增加签名校验，对路由映射也可以做更复杂的业务，如接口是否需要签名校验，再如增加业务统一的内容放到 header 中，增加接口限流等。
总结：
自定义网关是一个 spring-boot-web 项目，基于 RestTemplate 进行路由转发，通过 LoadBlance 实现负载均衡，通过拦截器实现路由映射、token 权限校验及其他业务内容。
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