发现问题并进行记录

项目场景：

RestTemplate也可以做服务调用(进行测试)

目的:解决该问题,不考虑其他远程调用方式(Fegin,Dubbo)

项目Pom文件

Spring Boot ----2.6.3
Spring Cloud------2021.0.1
Spring Cloud Alibaba-------2021.0.1.0

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.3</version>
        <relativePath/>
    </parent>


	 <properties>
        <spring-cloud.version>2021.0.1</spring-cloud.version>
        <spring-cloud-alibaba.version>2021.0.1.0</spring-cloud-alibaba.version>
    </properties>

    <dependencyManagement>
        <!-- springCloud -->
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <!-- spring cloud alibaba是阿里巴巴集团针对服务开发所提供的一套解决方案 -->
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>${spring-cloud-alibaba.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

---

问题描述

该项目有消费者端(consumer-service)和服务端(provider-service)

服务提供者接口正常

消费者端使用服务名进行调用

        //2远程查询用户信息
        String url="http://provider-server/provider/"+order.getUserId();

        //2. 发起调用
        User user = restTemplate.getForObject(url, User.class);

Nacos注册也成功

但是调用一直报错

找了很多文章,都不符合我的问题

报错如下:

Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@114f1cd5]
2023-07-04 14:53:53.067 ERROR 6596 --- [io-20087-exec-3] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause

java.lang.NullPointerException: null
	at java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:936) ~[na:1.8.0_201]
	at java.util.concurrent.ConcurrentHashMap.containsKey(ConcurrentHashMap.java:964) ~[na:1.8.0_201]
	at org.springframework.cloud.context.named.NamedContextFactory.getContext(NamedContextFactory.java:102) ~[spring-cloud-context-3.1.1.jar:3.1.1]
	at org.springframework.cloud.context.named.NamedContextFactory.getProvider(NamedContextFactory.java:161) ~[spring-cloud-context-3.1.1.jar:3.1.1]
	at org.springframework.cloud.context.named.ClientFactoryObjectProvider.delegate(ClientFactoryObjectProvider.java:115) ~[spring-cloud-context-3.1.1.jar:3.1.1]
	at org.springframework.cloud.context.named.ClientFactoryObjectProvider.getIfAvailable(ClientFactoryObjectProvider.java:64) ~[spring-cloud-context-3.1.1.jar:3.1.1]
	at com.alibaba.cloud.nacos.loadbalancer.NacosLoadBalancer.choose(NacosLoadBalancer.java:68) ~[spring-cloud-starter-alibaba-nacos-discovery-2021.0.1.0.jar:2021.0.1.0]
	at com.alibaba.cloud.nacos.loadbalancer.NacosLoadBalancer.choose(NacosLoadBalancer.java:47) ~[spring-cloud-starter-alibaba-nacos-discovery-2021.0.1.0.jar:2021.0.1.0]
	at org.springframework.cloud.loadbalancer.blocking.client.BlockingLoadBalancerClient.choose(BlockingLoadBalancerClient.java:155) ~[spring-cloud-loadbalancer-3.1.1.jar:3.1.1]
	at org.springframework.cloud.loadbalancer.blocking.client.BlockingLoadBalancerClient.execute(BlockingLoadBalancerClient.java:80) ~[spring-cloud-loadbalancer-3.1.1.jar:3.1.1]
	at org.springframework.cloud.client.loadbalancer.LoadBalancerInterceptor.intercept(LoadBalancerInterceptor.java:56) ~[spring-cloud-commons-3.1.1.jar:3.1.1]
	at org.springframework.http.client.InterceptingClientHttpRequest$InterceptingRequestExecution.execute(InterceptingClientHttpRequest.java:93) ~[spring-web-5.3.15.jar:5.3.15]
	at org.springframework.http.client.InterceptingClientHttpRequest.executeInternal(InterceptingClientHttpRequest.java:77) ~[spring-web-5.3.15.jar:5.3.15]
	at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48) ~[spring-web-5.3.15.jar:5.3.15]
	at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:66) ~[spring-web-5.3.15.jar:5.3.15]
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:776) ~[spring-web-5.3.15.jar:5.3.15]
	at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:711) ~[spring-web-5.3.15.jar:5.3.15]
	at org.springframework.web.client.RestTemplate.getForObject(RestTemplate.java:334) ~[spring-web-5.3.15.jar:5.3.15]
	at com.service.impl.ConsumerServiceImpl.queryOrderById(ConsumerServiceImpl.java:38) ~[classes/:na]
	at com.controller.ConsumerController.queryOrderByUserId(ConsumerController.java:27) ~[classes/:na]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_201]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_201]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_201]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_201]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-5.3.15.jar:5.3.15]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150) ~[spring-web-5.3.15.jar:5.3.15]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) ~[spring-webmvc-5.3.15.jar:5.3.15]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.3.15.jar:5.3.15]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.15.jar:5.3.15]
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.15.jar:5.3.15]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1067) ~[spring-webmvc-5.3.15.jar:5.3.15]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.15.jar:5.3.15]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.15.jar:5.3.15]
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.15.jar:5.3.15]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) ~[tomcat-embed-core-9.0.56.jar:4.0.FR]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.15.jar:5.3.15]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.56.jar:4.0.FR]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.56.jar:9.0.56]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.15.jar:5.3.15]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.15.jar:5.3.15]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.15.jar:5.3.15]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.15.jar:5.3.15]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.15.jar:5.3.15]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.15.jar:5.3.15]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:540) [tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) [tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) [tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382) [tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:895) [tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1732) [tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) [tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) [tomcat-embed-core-9.0.56.jar:9.0.56]
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.56.jar:9.0.56]
	at java.lang.Thread.run(Thread.java:748) [na:1.8.0_201]

---

原因分析

使用spring cloud alibaba时特别需要注意版本间的兼容关系请查看github官网wiki首页的: 版本说明文档

1. 开始怀疑版本问题造成的,但是翻阅很多资料也没发现问题
2. RestTemplate配置是否有问题(改了很多版本,很多播客说是MappingJackson2HttpMessageConverter进行配置)

       @Bean
       @LoadBalanced
       public RestTemplate restTemplate() {
           RestTemplate restTemplate = new RestTemplate();
           //   restTemplate.setRequestFactory(okHttpClient());
           //获取RestTemplate默认配置好的所有转换器
   //        List<HttpMessageConverter<?>> messageConverters = restTemplate.getMessageConverters();
           //默认的MappingJackson2HttpMessageConverter在第7个 先把它移除掉
   //        messageConverters.remove(6);
           //restTemplate.setErrorHandler(new DefaultResponseErrorHandler());
           return restTemplate;
       }
   
   

3. Nacos配置问题(改了很多版本,还是不行)
4. 通过discoveryClient连接nacos进行Debug进行处理不行

       //通过discoveryClient连接nacos
       @Autowired
       private DiscoveryClient discoveryClient;
   
       public String getPort(){
           //获取实例集合
           List<ServiceInstance> list = this.discoveryClient.getInstances("provider-server");
           //我们随机拿取其中的一个实例
           int index = ThreadLocalRandom.current().nextInt(list.size());
           ServiceInstance instance = list.get(index);
           //主机名加端口即为URI 如localhost:8080 加上/getPort 就是完整路径url
           String url = instance.getUri() + "/provider/1";
           //调用 第二个参数为调用接口的返回类型
           User forObject = restTemplate.getForObject(url, User.class);
           return "调用了 ";
       }
   

5. application.yml配置 改了很多(没用)

---

解决

最终解决了,但是很无语

包的命名不能仅仅是com,修改报名com为其他任意名字即可。如com.xing

1. 原始版本
   
2. 修改后
   
3. 成功返回