在公司中准备用websocker统计在线人数,在WebSocketServer使用StringRedisTemplate保存数据到redis中去,但是在保存的时候显示
StringRedisTemplate变量为null
详细问题
java
2023-08-20 10:37:14.109 ERROR 28240 --- [nio-7125-exec-1] o.a.t.websocket.pojo.PojoEndpointBase : Failed to call onClose method of POJO end point for POJO of type [com.example.pipayshopapi.component.WebSocketServer]
java.lang.reflect.InvocationTargetException: null
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.apache.tomcat.websocket.pojo.PojoEndpointBase.onClose(PojoEndpointBase.java:103) [tomcat-embed-websocket-9.0.41.jar:9.0.41]
at org.apache.tomcat.websocket.WsSession.fireEndpointOnClose(WsSession.java:556) [tomcat-embed-websocket-9.0.41.jar:9.0.41]
at org.apache.tomcat.websocket.WsSession.doClose(WsSession.java:502) [tomcat-embed-websocket-9.0.41.jar:9.0.41]
at org.apache.tomcat.websocket.WsSession.doClose(WsSession.java:460) [tomcat-embed-websocket-9.0.41.jar:9.0.41]
at org.apache.tomcat.websocket.WsSession.close(WsSession.java:447) [tomcat-embed-websocket-9.0.41.jar:9.0.41]
at org.apache.tomcat.websocket.WsSession.close(WsSession.java:441) [tomcat-embed-websocket-9.0.41.jar:9.0.41]
at org.apache.tomcat.websocket.pojo.PojoEndpointBase.handleOnOpenOrCloseError(PojoEndpointBase.java:92) [tomcat-embed-websocket-9.0.41.jar:9.0.41]
at org.apache.tomcat.websocket.pojo.PojoEndpointBase.doOnOpen(PojoEndpointBase.java:77) [tomcat-embed-websocket-9.0.41.jar:9.0.41]
at org.apache.tomcat.websocket.pojo.PojoEndpointServer.onOpen(PojoEndpointServer.java:64) [tomcat-embed-websocket-9.0.41.jar:9.0.41]
at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler.init(WsHttpUpgradeHandler.java:135) [tomcat-embed-websocket-9.0.41.jar:9.0.41]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:935) [tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1597) [tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.41.jar:9.0.41]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_382]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_382]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.41.jar:9.0.41]
at java.lang.Thread.run(Thread.java:750) [na:1.8.0_382]
Caused by: java.lang.NullPointerException: null
at com.example.pipayshopapi.component.WebSocketServer.onClose(WebSocketServer.java:70) ~[classes/:na]
... 21 common frames omitted
2023-08-20 10:37:14.109 ERROR 28240 --- [nio-7125-exec-1] c.e.p.component.WebSocketServer : 发生错误
java.lang.NullPointerException
at com.example.pipayshopapi.component.WebSocketServer.onOpen(WebSocketServer.java:56)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.tomcat.websocket.pojo.PojoEndpointBase.doOnOpen(PojoEndpointBase.java:65)
at org.apache.tomcat.websocket.pojo.PojoEndpointServer.onOpen(PojoEndpointServer.java:64)
at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler.init(WsHttpUpgradeHandler.java:135)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:935)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1597)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:750)
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.tomcat.websocket.pojo.PojoEndpointBase.onClose(PojoEndpointBase.java:103)
at org.apache.tomcat.websocket.WsSession.fireEndpointOnClose(WsSession.java:556)
at org.apache.tomcat.websocket.WsSession.doClose(WsSession.java:502)
at org.apache.tomcat.websocket.WsSession.doClose(WsSession.java:460)
at org.apache.tomcat.websocket.WsSession.close(WsSession.java:447)
at org.apache.tomcat.websocket.WsSession.close(WsSession.java:441)
at org.apache.tomcat.websocket.pojo.PojoEndpointBase.handleOnOpenOrCloseError(PojoEndpointBase.java:92)
at org.apache.tomcat.websocket.pojo.PojoEndpointBase.doOnOpen(PojoEndpointBase.java:77)
at org.apache.tomcat.websocket.pojo.PojoEndpointServer.onOpen(PojoEndpointServer.java:64)
at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler.init(WsHttpUpgradeHandler.java:135)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:935)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1597)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:750)
Caused by: java.lang.NullPointerException
at com.example.pipayshopapi.component.WebSocketServer.onClose(WebSocketServer.java:70)
... 21 more
最后在网上搜索之后得出答案:
因为spring对象的创建都是以单例模式创建的,但是每一个用户连接websocker,都会创建一次webscket对象,所以当你启动项目时,你想要注入的对象已经注入进去,但是当用户连接是,新创建的websocket对象没有你要注入的对象,所以会报NullPointerException。
总结:spring管理的都是单例(singleton),和 websocket (多对象)相冲突.
解决方法:
在WebSocketServer中,使用set方法传入上下文
java
private static StringRedisTemplate stringRedisTemplate;
@Autowired
public void setChatService(StringRedisTemplate stringRedisTemplate) {
WebSocketServer.stringRedisTemplate = stringRedisTemplate;
}
完整代码
java
import com.example.pipayshopapi.service.UserInfoService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;
import javax.annotation.Resource;
import javax.websocket.*;
import javax.websocket.server.PathParam;
import javax.websocket.server.ServerEndpoint;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
/**
* @author websocket服务
*/
@Component
@ServerEndpoint(value = "/dailyActive/{userId}")
public class WebSocketServer {
private static final Logger log = LoggerFactory.getLogger(WebSocketServer.class);
// 注入查看聊天列表的服务
/**
* 记录当前在线连接数
*/
public static final Map<String, Session> dailyActiveCount = new ConcurrentHashMap<>();
public static final String dailyActiveName="dailyActiveName";
private RedisHandler redisHandler=RedisHandler.getInstance();
private static StringRedisTemplate stringRedisTemplate;
@Autowired
public void setChatService(StringRedisTemplate stringRedisTemplate) {
WebSocketServer.stringRedisTemplate = stringRedisTemplate;
}
/**
* 连接建立成功调用的方法
*/
@OnOpen
public void onOpen(Session session, @PathParam("userId") String userId) {
log.error(userId+"----------------------------------------------进入");
// 保存当前用户session
dailyActiveCount.put(userId, session);
// 存入redis中去
// redisHandler.savedailyActive(dailyActiveName,dailyActiveCount.size());
stringRedisTemplate.opsForValue().set(dailyActiveName,String.valueOf(dailyActiveCount.size()));
}
/**
* 连接关闭调用的方法
*/
@OnClose
public void onClose(Session session, @PathParam("userId") String userId) {
log.error(userId+"----------------------------------------------关闭");
// 移除当前用户session
dailyActiveCount.remove(userId);
// 存入redis中去
// redisHandler.savedailyActive(dailyActiveName,dailyActiveCount.size());
stringRedisTemplate.opsForValue().set(dailyActiveName,String.valueOf(dailyActiveCount.size()));
}
/**
* 收到客户端消息后调用的方法
* 后台收到客户端发送过来的消息
* onMessage 是一个消息的中转站
* 接受 浏览器端 socket.send 发送过来的 json数据
*/
@OnMessage
public void onMessage(Session session, String message,@PathParam("userId") String userId) {
}
@OnError
public void onError(Session session, Throwable error) {
log.error("发生错误");
error.printStackTrace();
}
}