我一直在使用Websockets开发项目,并且在多个类和线程中需要相同的HashMap。阅读了一段时间后,我发现使用@Resource注释是最好的。但是我无法使其工作,并且在打印String时仅获取null,而对ConcurrentHashMap进行任何操作时均得到NullPointerException。这是代码的一部分。
SocketHandler.java
@Component
public class SocketHandler extends TextWebSocketHandler {
@Resource(name = "teststring")
private String testString;
private ConcurrentHashMap<WebSocketSession, UserPlayer> sessions;
@Resource(name="sessions")
public void setSessions(ConcurrentHashMap<WebSocketSession, UserPlayer> sessions){
System.out.println("Im in @resource");
this.sessions=sessions;
}
@Override
public void afterConnectionEstablished(final WebSocketSession session) throws Exception {
System.out.println(testString);
sessions.put(session, new UserPlayer());
System.out.println("Got connection " + session);
}
}
AplicationContextResource.java
@Configuration
public class ApplicationContextResource{
@Bean(name="sessions")
public ConcurrentHashMap<WebSocketSession, UserPlayer> sessions(){
ConcurrentHashMap<WebSocketSession, UserPlayer> sessions = new ConcurrentHashMap<WebSocketSession, UserPlayer>();
System.out.println("bean sessions!!");
return sessions;
}
@Bean(name="teststring")
public String testString(){
String str = new String("12345");
return str;
}
}
BeanPostProc.java
@Configuration
public class BeanPostProc {
@Bean
public CommonAnnotationBeanPostProcessor commonAnnotationBeanPostProcessor(){
CommonAnnotationBeanPostProcessor cBeanPostProcessor = new CommonAnnotationBeanPostProcessor();
cBeanPostProcessor.setAlwaysUseJndiLookup(true);
return cBeanPostProcessor;
}
}
这是服务器启动和客户端连接后的控制台输出。
020-05-07 22:03:28.417 INFO 3132 --- [ main] com.soluna.slith.DemoApplication : Starting DemoApplication on Racunalo with PID 3132 (D:\Git\slytherin\server\slith\target\classes started by Sebastijan in d:\Git\slytherin\server\slith)
2020-05-07 22:03:28.421 INFO 3132 --- [ main] com.soluna.slith.DemoApplication : No active profile set, falling back to default profiles: default
2020-05-07 22:03:29.395 INFO 3132 --- [ main] trationDelegate$BeanPostProcessorChecker : Bean 'beanPostProc' of type [com.soluna.slith.config.BeanPostProc$$EnhancerBySpringCGLIB$$524027f] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2020-05-07 22:03:29.758 INFO 3132 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2020-05-07 22:03:29.771 INFO 3132 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2020-05-07 22:03:29.772 INFO 3132 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.30]
2020-05-07 22:03:29.874 INFO 3132 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2020-05-07 22:03:29.875 INFO 3132 --- [ main] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 1365 ms
bean sessions!!
Im in @resource
2020-05-07 22:03:30.193 INFO 3132 --- [ main] o.s.s.concurrent.ThreadPoolTaskExecutor : Initializing ExecutorService 'applicationTaskExecutor'
2020-05-07 22:03:30.458 INFO 3132 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2020-05-07 22:03:30.461 INFO 3132 --- [ main] com.soluna.slith.DemoApplication : Started DemoApplication in 2.511 seconds (JVM running for 3.154)
2020-05-07 22:04:31.705 INFO 3132 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring DispatcherServlet 'dispatcherServlet'
2020-05-07 22:04:31.705 INFO 3132 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : Initializing Servlet 'dispatcherServlet'
2020-05-07 22:04:31.722 INFO 3132 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : Completed initialization in 17 ms
null
2020-05-07 22:04:31.808 ERROR 3132 --- [nio-8080-exec-1] w.s.h.ExceptionWebSocketHandlerDecorator : Closing session due to exception for StandardWebSocketSession[id=6aedf417-075a-851d-bb92-16e32ef76915, uri=ws://localhost:8080/game]
java.lang.NullPointerException: null
at com.soluna.slith.controller.SocketHandler.afterConnectionEstablished(SocketHandler.java:65) ~[classes/:na]
我的项目没有XML,所有示例都显示了基于XML的bean配置。尝试使用和不使用.setAlwaysUseJndiLookup(true)。我是否用CommonAnnotationBeanPostProcessor bean搞砸了?
最佳答案
在阅读并尝试了很多东西之后,我终于找到了错误。
错误不是上述任何类中的,而是WebSocket配置中的。
甚至不需要带有CommonAnnotationBeanPostProcessor的BeanPostProc.java。
WebSocket配置之前:
@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {
@Override
public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
registry.addHandler(new SocketHandler(), "/game").setAllowedOrigins("*");
}
}
现在进行WebSocket配置:
@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {
@Autowired
private SocketHandler socketHandler;
@Override
public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
registry.addHandler(socketHandler, "/game").setAllowedOrigins("*");
}
}
错误是我正在创建一个新的SocketHandler实例,该实例不是由Spring管理的,并且未正确自动接线。
修复错误后,Bean注入可与@Resource和@Autowired批注一起使用。