Springboot2.7集成websocket及相关问题

1、集成websocket完整代码

导入maven依赖

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-websocket</artifactId>
</dependency>

服务端代码

（1）注入bean
@Configuration
@EnableWebSocket
public class WebSocketConfig {@Beanpublic ServerEndpointExporter serverEndpointExporter() {return new ServerEndpointExporter();}
}
（2）服务端开放的服务及其业务逻辑
@Slf4j
@Component
@ServerEndpoint("/testcase/page/{clientId}")
//@Lazy
public class WsMessageService {//与某个客户端的连接会话private Session session;//存放每个客户端对应的WebSocket对象。private static Map<String, WsMessageService> webSocketsBeanMap = new ConcurrentHashMap<>();//每次连接都是一个新的会话对象，线程安全的String userId;//注入业务类。要注意setTestcaseService()的名称不能错，set后的字符串要和要注入的变量名一致。private static TestcaseService testcaseService;@Autowiredpublic void setTestcaseService(TestcaseService testcaseService) {WsMessageService.testcaseService= testcaseService;}//private TestcaseService testcaseService = SpringContextUtil.getBean(TestcaseService.class);@OnOpenpublic void onOpen(Session session, @PathParam(value = "clientId") String userId) {this.session = session;this.userId = userId;webSocketsBeanMap.put(userId, this);log.info("OnOpen连接成功，userId：{}，当前在线人数：{}", userId, this.getOnLineCount());}@OnMessagepublic void onMessage(String message) throws IOException {Session session = webSocketsBeanMap.get(this.userId).session;if (session==null || !session.isOpen()) {return;}log.info("收到客户端的消息:" + message);//start业务Integer pageNum = null;Integer pageSize = null;String pid = null;String vid = null;if (session.getRequestParameterMap().get("pageNum")!= null) {pageNum = Integer.valueOf(session.getRequestParameterMap().get("pageNum").get(0));}if (session.getRequestParameterMap().get("pageNum")!= null) {pageSize = Integer.valueOf(session.getRequestParameterMap().get("pageSize").get(0));}if (session.getRequestParameterMap().get("pid")!= null) {pid = session.getRequestParameterMap().get("pid").get(0);}if (session.getRequestParameterMap().get("vid")!= null) {vid = session.getRequestParameterMap().get("vid").get(0);}PageInfo<TestcasePageVO> pageInfo = testcaseService.findTestcaseByMultiCondition(pageNum, pageSize, pid, vid);//end业务try {JSONObject object = new JSONObject();object.put("data", pageInfo);object.put("code", 200);object.put("message", "SUCCESS");this.session.getBasicRemote().sendText(String.valueOf(object.toString()));} catch (IOException e) {throw new RuntimeException(e);}}@OnClosepublic void onClose() throws IOException {log.info("会话关闭，关闭会话的用户Id为：{}", this.userId);webSocketsBeanMap.remove(this.userId);log.info("当前在线人数：{}", this.getOnLineCount());}@OnErrorpublic void onError(Session session, Throwable error) {log.error("连接错误：" + error.getMessage());error.printStackTrace();}private int getOnLineCount() {return webSocketsBeanMap.size();}
}

测试服务端的可用性。在浏览器的控制台输入以下代码可以测试。

function initWebSocket(wsUri) {var websocket = new WebSocket(wsUri);websocket.onopen = function(evt) {console.log('连接建立中... '+wsUri);};websocket.onclose = function(evt) {console.log('连接关闭中...', evt);};websocket.onmessage = function(evt) {console.log('收到来自服务端的消息：', evt.data);};websocket.onerror = function(evt) {console.log('发生错误...', evt);};return websocket;}var websocket = initWebSocket("ws://ip:port/testcase/page/123?pid=5922cc3d03f74012a7112c931c8497d7&vid=fc2d7a6049ff4c7bafc40bf659b4e903");var msg, i = 0;var loop = setInterval(function(){msg = "Hello " +(i++);if(websocket.readyState == WebSocket.OPEN) {websocket.send(msg);console.log('已发送消息：' +msg);} else{clearInterval(loop);console.log('连接已关闭');}}, 10000);

2、集成websocket另一种方法（用控制台测试时返回的数据会乱码）

代码找不到了。但那种方法有一个特征就是使用的注解比当前的方法少。

3、解决业务类注入不进去的问题（两种方法，推荐第一种）

（1）第一种：就是当前使用的注入方法。注意命名，否则不会注入成功

//注入业务类。要注意setTestcaseService()的名称不能错，set后的字符串要和要注入的变量名一致。private static TestcaseService testcaseService;@Autowiredpublic void setTestcaseService(TestcaseService testcaseService) {WsMessageService.testcaseService= testcaseService;}

（2）第二种：自己写一个SpringContextUtil工具类，协助注入

package cn.xxxxx.tmMaster.utils;import lombok.extern.slf4j.Slf4j;
import org.mybatis.logging.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;import java.util.logging.Logger;@Slf4j
@Component
public class SpringContextUtil implements ApplicationContextAware {private static ApplicationContext applicationContext;@Overridepublic void setApplicationContext(ApplicationContext applicationContext) throws BeansException {SpringContextUtil.applicationContext = applicationContext;}/*** 获取 applicationContext*/public static ApplicationContext getApplicationContext() {return applicationContext;}/*** 通过 name 获取 bean 对象*/public static Object getBean(String name) {return getApplicationContext().getBean(name);}/*** 通过 class 获取 bean 对象*/public static <T> T getBean(Class<T> clazz) {return getApplicationContext().getBean(clazz);}/*** 通过 name，clazz  获取指定的 bean 对象*/public static <T> T getBean(String name, Class<T> clazz) {return getApplicationContext().getBean(name, clazz);}
}

在WsMessageService中使用如下代码注入进去，但在类上必须要@Lazy进行懒加载，否则会报错

@Lazy
public class WsMessageService {
……private TestcaseService testcaseService = SpringContextUtil.getBean(TestcaseService.class);
……
}

不加@Lazy报错如下：org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'wsMessageService' defined in file [D:\javaworkspace\test-xxxx\tm-master\target\classes\cn\xxxxx\tmMaster\service\testcase\WsMessageService.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [cn.xxxxx.tmMaster.service.testcase.WsMessageService]: Constructor threw exception; nested exception is java.lang.NullPointerException

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'wsMessageService' defined in file [D:\javaworkspace\test-xxxx\tm-master\target\classes\cn\xxxxx\tmMaster\service\testcase\WsMessageService.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [cn.xxxxx.tmMaster.service.testcase.WsMessageService]: Constructor threw exception; nested exception is java.lang.NullPointerExceptionat org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1334) ~[spring-beans-5.3.29.jar:5.3.29]at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1232) ~[spring-beans-5.3.29.jar:5.3.29]at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582) ~[spring-beans-5.3.29.jar:5.3.29]at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.29.jar:5.3.29]at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.29.jar:5.3.29]at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.29.jar:5.3.29]at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.29.jar:5.3.29]at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.29.jar:5.3.29]at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:955) ~[spring-beans-5.3.29.jar:5.3.29]at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:921) ~[spring-context-5.3.29.jar:5.3.29]at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583) ~[spring-context-5.3.29.jar:5.3.29]at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:147) ~[spring-boot-2.7.14.jar:2.7.14]at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:731) [spring-boot-2.7.14.jar:2.7.14]at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:408) [spring-boot-2.7.14.jar:2.7.14]at org.springframework.boot.SpringApplication.run(SpringApplication.java:307) [spring-boot-2.7.14.jar:2.7.14]at org.springframework.boot.SpringApplication.run(SpringApplication.java:1303) [spring-boot-2.7.14.jar:2.7.14]at org.springframework.boot.SpringApplication.run(SpringApplication.java:1292) [spring-boot-2.7.14.jar:2.7.14]at cn.xxxxx.tmMaster.MasterApplication.main(MasterApplication.java:17) [classes/:na]at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_382]at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_382]at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_382]at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_382]at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:50) [spring-boot-devtools-2.7.14.jar:2.7.14]
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [cn.xxxxx.tmMaster.service.testcase.WsMessageService]: Constructor threw exception; nested exception is java.lang.NullPointerExceptionat org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:224) ~[spring-beans-5.3.29.jar:5.3.29]at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:87) ~[spring-beans-5.3.29.jar:5.3.29]at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1326) ~[spring-beans-5.3.29.jar:5.3.29]... 22 common frames omitted
Caused by: java.lang.NullPointerException: nullat cn.xxxxx.tmMaster.utils.SpringContextUtil.getBean(SpringContextUtil.java:55) ~[classes/:na]at cn.xxxxx.tmMaster.service.testcase.WsMessageService.<init>(WsMessageService.java:48) ~[classes/:na]at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_382]at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_382]at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_382]at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_382]at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:211) ~[spring-beans-5.3.29.jar:5.3.29]... 24 common frames omitted

参考资料：

SpringBoot集成WebSocket实现客户端与服务端长连接通信_springboot实现websocket客户端_拄杖忙学轻声码的博客-CSDN博客 SpringBoot集成WebSocket实现客户端与服务端长连接通信

快速搭建springboot websocket客户端_springboot实现websocket客户端_wcybaonier的博客-CSDN博客 快速搭建springboot websocket客户端