Nacos服务注册成功,RestTemplate调用服务提供者时空指针异常（已解决）

拼搏现实的明天。 2024-03-17 14:45 70阅读 0赞

> `发现问题并进行记录`

#### 目录 ####

*  项目场景：
 *  问题描述
 *  原因分析
 *  解决

## 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>
            
            <dependencies>
                <dependency>
                    <groupId>org.springframework.cloud</groupId>
                    <artifactId>spring-cloud-dependencies</artifactId>
                    <version>${spring-cloud.version}</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
                
                <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>

--------------------

![在这里插入图片描述][ccc1a10f3ba1459eaf8440a364b4e7fe.png]

## 问题描述 ##

![在这里插入图片描述][ffba38848ee046359c3589ccf9db164c.png]

该项目有`消费者端(consumer-service)`和`服务端(provider-service)`

![在这里插入图片描述][601c8419998c48808a4e7ef74432d8ec.png]

**`服务提供者接口正常`**

![在这里插入图片描述][ced4986506044b72bcfbcd90b7ccadc8.png]

**`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`  
![在这里插入图片描述][8922ee0351a4474ca7692d94ef6d06e4.png]

`但是调用一直报错`

**找了很多文章,都不符合我的问题**

![在这里插入图片描述][bdb912934c9948fbba77d7be8dcc18a4.png]  
`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][Link 1]

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  
    ![在这里插入图片描述][ccc1a10f3ba1459eaf8440a364b4e7fe.png]
2.  修改后  
    ![在这里插入图片描述][d22aeeb2e0884cd5a181f07cd977821f.png]
3.  成功返回  
    ![在这里插入图片描述][333e275207ab4d9c8f0ca878c9c1a4a4.png]![在这里插入图片描述][1301882df859b7fbe1dd446ce7f0370c.gif_pic_center][![在这里插入图片描述][9352bed7646600067afd910c6f313135.gif_pic_center]][9352bed7646600067afd910c6f313135.gif_pic_center 1]

[ccc1a10f3ba1459eaf8440a364b4e7fe.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/cf13cd61ccb5403da4882ffd9c6faf72.png
[ffba38848ee046359c3589ccf9db164c.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/27e8e8fde5cd4b95ac53d77e23730624.png
[601c8419998c48808a4e7ef74432d8ec.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/ad3756818f32433ebaa2068f7b9b1e26.png
[ced4986506044b72bcfbcd90b7ccadc8.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/c39925f959cc4169969be656e9c84224.png
[8922ee0351a4474ca7692d94ef6d06e4.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/913ac78ca04846498e1cbd1ca756c3c0.png
[bdb912934c9948fbba77d7be8dcc18a4.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/3f7694eb9c0a488eb83a57400872e360.png
[Link 1]: https://github.com/alibaba/spring-cloud-alibaba/wiki/%E7%89%88%E6%9C%AC%E8%AF%B4%E6%98%8E
[d22aeeb2e0884cd5a181f07cd977821f.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/6f458d591fd8441fa64a412cb4cb9c2d.png
[333e275207ab4d9c8f0ca878c9c1a4a4.png]: https://img-blog.csdnimg.cn/333e275207ab4d9c8f0ca878c9c1a4a4.png
[1301882df859b7fbe1dd446ce7f0370c.gif_pic_center]: https://img-blog.csdnimg.cn/img_convert/1301882df859b7fbe1dd446ce7f0370c.gif#pic_center
[9352bed7646600067afd910c6f313135.gif_pic_center]: https://img-blog.csdnimg.cn/img_convert/9352bed7646600067afd910c6f313135.gif#pic_center
[9352bed7646600067afd910c6f313135.gif_pic_center 1]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/4ee5b83d459e4da286b0bd1299539672.png