系统的大致情况：Spring Cloud的项目，共四个服务，一个是Eureka服务器，一个前端服务，两个后端服务，服务之间的接口调用通过FeignClient进行调用，项目配置为https，用的是命令生成的证书，所以证书校验会有问题，所以启动Eureka Server后，再启其他服务时，向Eureka服务器发送注册请求时，会有报错，证书校验失败，针对这个问题解决时把证书通过浏览器导出存为.cer文件，然后用命令把.cer证书加到jdk的证书信任列表。

命令如下：keytool -import -keystore "%JAVA_HOME%/jre/lib/security/cacerts"  -storepass changeit -keypass changeit -alias cloud -file cloud.cer

注：-storepass changeit这个是jdk证书列表的默认密码，一般不需要改，

 -alias 指定的是证书别名，这个是不是要和创建证书时一致，我也不太清楚，不过还是尽量一致吧，免得有麻烦，但是不能和 列表里已有的证书别名重，这个是确定的，

 -file后面是文件路径，如果是在证书所在目录下执行的命令，就加证书名就行了

这样服务启动注册到Eureka就没有问题了，但是服务之间通过FeignClient调接口时却还是报了证书校验的错，异常栈如下：

Caused by: feign.RetryableException: java.security.cert.CertificateException: No subject alternative names present executing GET http://cts-master/cts-master/role/getAllRoles
	at feign.FeignException.errorExecuting(FeignException.java:67)
	at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:104)
	at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:76)
	at feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:103)
	at com.sun.proxy.$Proxy113.getAllRoles(Unknown Source)
	at com.pcitc.cts.web.service.impl.RoleServiceImpl.setRoleMap(RoleServiceImpl.java:38)
	at com.pcitc.cts.web.service.impl.RoleServiceImpl.setServletContext(RoleServiceImpl.java:33)
	at org.springframework.web.context.support.ServletContextAwareProcessor.postProcessBeforeInitialization(ServletContextAwareProcessor.java:103)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:408)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1570)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545)
	... 35 more
Caused by: javax.net.ssl.SSLHandshakeException: java.security.cert.CertificateException: No subject alternative names present
	at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
	at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1959)
	at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:302)
	at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:296)
	at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1514)
	at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:216)
	at sun.security.ssl.Handshaker.processLoop(Handshaker.java:1026)
	at sun.security.ssl.Handshaker.process_record(Handshaker.java:961)
	at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1072)
	at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1385)
	at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1413)
	at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1397)
	at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:559)
	at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185)
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1564)
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1492)
	at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:480)
	at sun.net.www.protocol.https.HttpsURLConnectionImpl.getResponseCode(HttpsURLConnectionImpl.java:347)
	at feign.Client$Default.convertResponse(Client.java:152)
	at feign.Client$Default.execute(Client.java:74)
	at org.springframework.cloud.netflix.feign.ribbon.FeignLoadBalancer.execute(FeignLoadBalancer.java:81)
	at org.springframework.cloud.netflix.feign.ribbon.FeignLoadBalancer.execute(FeignLoadBalancer.java:49)
	at com.netflix.client.AbstractLoadBalancerAwareClient$1.call(AbstractLoadBalancerAwareClient.java:109)
	at com.netflix.loadbalancer.reactive.LoadBalancerCommand$3$1.call(LoadBalancerCommand.java:303)
	at com.netflix.loadbalancer.reactive.LoadBalancerCommand$3$1.call(LoadBalancerCommand.java:287)
	at rx.internal.util.ScalarSynchronousObservable$3.call(ScalarSynchronousObservable.java:231)
	at rx.internal.util.ScalarSynchronousObservable$3.call(ScalarSynchronousObservable.java:228)
	at rx.Observable.unsafeSubscribe(Observable.java:10211)
	at rx.internal.operators.OnSubscribeConcatMap$ConcatMapSubscriber.drain(OnSubscribeConcatMap.java:286)
	at rx.internal.operators.OnSubscribeConcatMap$ConcatMapSubscriber.onNext(OnSubscribeConcatMap.java:144)
	at com.netflix.loadbalancer.reactive.LoadBalancerCommand$1.call(LoadBalancerCommand.java:185)
	at com.netflix.loadbalancer.reactive.LoadBalancerCommand$1.call(LoadBalancerCommand.java:180)
	at rx.Observable.unsafeSubscribe(Observable.java:10211)
	at rx.internal.operators.OnSubscribeConcatMap.call(OnSubscribeConcatMap.java:94)
	at rx.internal.operators.OnSubscribeConcatMap.call(OnSubscribeConcatMap.java:42)
	at rx.Observable.unsafeSubscribe(Observable.java:10211)
	at rx.internal.operators.OperatorRetryWithPredicate$SourceSubscriber$1.call(OperatorRetryWithPredicate.java:127)
	at rx.internal.schedulers.TrampolineScheduler$InnerCurrentThreadScheduler.enqueue(TrampolineScheduler.java:73)
	at rx.internal.schedulers.TrampolineScheduler$InnerCurrentThreadScheduler.schedule(TrampolineScheduler.java:52)
	at rx.internal.operators.OperatorRetryWithPredicate$SourceSubscriber.onNext(OperatorRetryWithPredicate.java:79)
	at rx.internal.operators.OperatorRetryWithPredicate$SourceSubscriber.onNext(OperatorRetryWithPredicate.java:45)
	at rx.internal.util.ScalarSynchronousObservable$WeakSingleProducer.request(ScalarSynchronousObservable.java:276)
	at rx.Subscriber.setProducer(Subscriber.java:209)
	at rx.internal.util.ScalarSynchronousObservable$JustOnSubscribe.call(ScalarSynchronousObservable.java:138)
	at rx.internal.util.ScalarSynchronousObservable$JustOnSubscribe.call(ScalarSynchronousObservable.java:129)
	at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
	at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
	at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
	at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
	at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
	at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
	at rx.Observable.subscribe(Observable.java:10307)
	at rx.Observable.subscribe(Observable.java:10274)
	at rx.observables.BlockingObservable.blockForSingle(BlockingObservable.java:445)
	at rx.observables.BlockingObservable.single(BlockingObservable.java:342)
	at com.netflix.client.AbstractLoadBalancerAwareClient.executeWithLoadBalancer(AbstractLoadBalancerAwareClient.java:102)
	at org.springframework.cloud.netflix.feign.ribbon.LoadBalancerFeignClient.execute(LoadBalancerFeignClient.java:63)
	at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:97)
	... 44 more
Caused by: java.security.cert.CertificateException: No subject alternative names present
	at sun.security.util.HostnameChecker.matchIP(HostnameChecker.java:145)
	at sun.security.util.HostnameChecker.match(HostnameChecker.java:94)
	at sun.security.ssl.X509TrustManagerImpl.checkIdentity(X509TrustManagerImpl.java:455)
	at sun.security.ssl.X509TrustManagerImpl.checkIdentity(X509TrustManagerImpl.java:436)
	at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:200)
	at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:124)
	at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1496)
	... 97 more

经过一翻折腾解决了该问题，具体解决的方法如下：

@Bean
    @ConditionalOnMissingBean
    public Client feignClient(CachingSpringLoadBalancerFactory cachingFactory,
                              SpringClientFactory clientFactory) throws NoSuchAlgorithmException, KeyManagementException {
        SSLContext ctx = SSLContext.getInstance("SSL");
        X509TrustManager tm = new X509TrustManager() {
            @Override
            public void checkClientTrusted(X509Certificate[] chain,
                                           String authType) throws CertificateException {
            }
            @Override
            public void checkServerTrusted(X509Certificate[] chain,
                                           String authType) throws CertificateException {
            }
            @Override
            public X509Certificate[] getAcceptedIssuers() {
                return null;
            }
        };
        ctx.init(null, new TrustManager[]{tm}, null);
        return new LoadBalancerFeignClient(new Client.Default(ctx.getSocketFactory(),
                new HostnameVerifier() {
                    public boolean verify(String hostname, SSLSession sslSession) {
                        return true;
                    }
                }),
                cachingFactory, clientFactory);
    }

因为系统设计为支持集群的，要走ribbon的负载均衡，所以需要配置为LoadBalancerFeignClient。加上这个配置后，即解决了上面报错。