爱站程序员基地小伙伴遇到个问题，某个controller发布的http服务直接访问没问题，通过nginx转发后就报404，此模块其他url访问都正常。。controller代码如下：
@RequestMapping(\"/addrExport.spr\")public class AddrExportController@RequestMapping(params = \"method=exportDynamicQueryData\")public void exportDynamicQueryData(HttpServletRequest request, HttpServletResponse response, String downLoadData) {System.out.println(\"hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh\");.....}
springboot应用，未配置上下文根。所以此http服务未使用nginx转发时的直接访问地址为：http://localhost:8299/addrExport.spr?method=exportDynamicQueryData前台ajax调用url：nginx映射路径：
server {listen 8888;......location /portal/space-addr/ {proxy_pass http://localhost:8299/space-addr/;}.....}
使用nginx端口访问的url如下，就是此url访问404http://localhost:8888/portal/space-addr/addrExport.spr?method=exportDynamicQueryData一阵兵荒马乱，小伙伴发现此url转发到后台的路径为http://localhost:8299/space-addr/addrExport.spr?method=exportDynamicQueryData 多了一个space-addr此时有两种方案，方案1.在controller里@RequestMapping时增加space-addr前缀方案2.修改nginx映射去掉proxy_pass中多余的前缀，注意红色字体部分去掉了space-addr，见下文：
location /portal/space-addr/ {
proxy_pass http://localhost:8299/;
}
采用方案2修改nginx配置验证后发现确实能解决问题。但问题来了。。。。修改nginx转发规则后，此模块原来正常访问的的功能应该报错才对，但事实上这些请求顺畅无比，仿佛世界从未发生改变，也就是说这些url在nginx转发规则增加space-addr和去掉space-addr时都可以正常访问。这真的不科学。。。。。此处省略走过的弯路。。。抓包查看了这些访问正常的功能对应的请求，发现都是一样的url，只是参数不同：http://localhost:8888/portal/space-addr/rescommon/service/callServerFunction查看此url对应的controller（ResCommonServiceController，隐藏特别深，由公共模块提供，见下图）发现：类上无@RequestMapping注解，也无@Controller或者@RestController注解，方法上此注解的value=callServerFunction。而根据nginx转发规则，此注解的value至少应该包含rescommon/service/callServerFunction。那么缺失的rescommon/service是在哪里被拼接的呢？
感谢spring的日志输出，偶然搜索发现了如下内容，什么鬼，竟然增加了两个rescommon/service/callServerFunction相关的requestmapping：一个有space-addr前缀，一个无前缀。。最终发现公共侧对ResCommonServiceController做了特殊处理，具体见CommonConfig类的registerCommonServerMapping方法(见下图)，默认会生成两个requestmapping：1./rescommon/service/callServerFunction2.${pub.commonservice.prefix}/rescommon/service/callServerFunction,对于排查问题的这个模块存在配置pub.commonservice.prefix=space-addr，最终效果为space-addr/rescommon/service/callServerFunction正是因为生成了两个requestmapping，所以才会出现nginx里转发规则配或不配space-addr都没问题的情况，因为都能匹配到requestmapping。。
类全文如下：
1 @Configuration2 public class CommonConfig {34 @Value(\"${pub.commonservice.prefix}\")5 String prefix;67 @Bean8 public ResCommonServiceController registerCommonServiceController() {9 return new ResCommonServiceController();10 }1112 @Autowired13 public void registerCommonServerMapping(ResCommonServiceController registerCommonServiceController, RequestMappingHandlerMapping mapping) {14 String uri = \"/rescommon/service/\";15 RequestMappingInfo requestMappingInfo = RequestMappingInfo.paths(uri).build();16 ResRequestMappingHandlerMapping resRequestMappingHandlerMapping = new ResRequestMappingHandlerMapping(mapping, requestMappingInfo);17 resRequestMappingHandlerMapping.detectHandlerMethods(registerCommonServiceController);18 if (!(\"\".equals(prefix) || prefix == null || \"${pub.commonservice.prefix}\".equals(prefix))) {19 String[] split = prefix.split(\",\");20 for (String prefix1 : split) {21 ResRequestMappingHandlerMapping resRequestMappingHandlerMapping1 = new ResRequestMappingHandlerMapping(mapping, RequestMappingInfo.paths(prefix1 + uri).build());22 resRequestMappingHandlerMapping1.detectHandlerMethods(registerCommonServiceController);23 }24 }25 }26 }
这个写法很有趣，第一次见。。自定义的ResRequestMappingHandlerMapping类扩展了spring的RequestMappingHandlerMapping，覆写了detectHandlerMethods方法，在registerMapping时将自定义的url前缀和method上的url做拼接。
1 public class ResRequestMappingHandlerMapping extends RequestMappingHandlerMapping {23 /**4 * 代理对象5 */6 private RequestMappingHandlerMapping requestMappingHandlerMapping;78 /**9 * 存放类的RequestMapping信息10 */11 RequestMappingInfo typeMapping;1213 public ResRequestMappingHandlerMapping(RequestMappingHandlerMapping requestMappingHandlerMapping, RequestMappingInfo typeMapping) {14 this.requestMappingHandlerMapping = requestMappingHandlerMapping;15 this.typeMapping = typeMapping;16 }1718 @Override19 public void detectHandlerMethods(final Object handler) {20 if(handler == null){21 return;22 }23 Class<?> handlerType = (handler instanceof String ? getApplicationContext().getType((String) handler) : handler.getClass());24 final Class<?> userType = ClassUtils.getUserClass(handlerType);2526 Map<Method, RequestMappingInfo> methods = MethodIntrospector.selectMethods(userType, new MethodIntrospector.MetadataLookup<RequestMappingInfo>() {27 public RequestMappingInfo inspect(Method method) {28 try {29 return getMappingForMethod(method, userType);30 }31 catch (Exception ex) {32 throw new IllegalStateException(\"Invalid mapping on handler class [\" + userType.getName() + \"]: \" + method, ex);33 }34 }35 });3637 if (logger.isDebugEnabled()) {38 logger.debug(methods.size() + \" request handler methods found on \" + userType + \": \" + methods);39 }40 for (Map.Entry<Method, RequestMappingInfo> entry : methods.entrySet()) {41 Method invocableMethod = AopUtils.selectInvocableMethod(entry.getKey(), userType);42 RequestMappingInfo mapping = entry.getValue();43 if (typeMapping != null) {44 mapping = typeMapping.combine(mapping);45 }46 requestMappingHandlerMapping.registerMapping(mapping, handler, invocableMethod);47 }48 }
至此，谜题解开了，因为公共侧对ResCommonServiceController类做了特殊定制，使其发布的@RequestMapping方法发布了两个http服务。。所以nginx的转发规则带不带前缀都不影响功能使用。。
