我有一个 TaskScheduler 类,如下所示:
public class NotificationManger {
@Autowired
private TaskScheduler scheduler;
private ScheduledFuture<?> sc;
public NotificationManger(WebSocketMessage webSocketMessage, String userName, Date date, Date time) {
scheduleTask(webSocketMessage, userName, combine(date,time));
}
public void scheduleTask(WebSocketMessage webSocketMessage, String userName, Date startTime)
{
Runnable r = new NotificationSenderTask(webSocketMessage, userName);
sc = scheduler.schedule(r, new Date());//here I get a NullPointerException
}
}
和一个 Runnable 类,如下所示:
class NotificationSenderTask implements Runnable {
@Autowired
SimpMessagingTemplate webSocketMessageTemplate;
private String userName;
private WebSocketMessage webSocketMessage;
public NotificationSenderTask(WebSocketMessage webSocketMessage, String userName) {
this.webSocketMessage = webSocketMessage;
this.userName = userName;
}
public void run() {
webSocketMessageTemplate.convertAndSendToUser(userName, "/notification", webSocketMessage);;
}
}
我调用TaskScheduler:
NotificationManger mn = new NotificationManger(new WebSocketMessage(n), user.getEmail(),date1,date2 );
但我越来越
java.lang.NullPointerException: null
在
sc = scheduler.schedule(r, new Date());
也许我使用的可运行类是错误的?
@EnableWebMvc
@EnableGlobalMethodSecurity(prePostEnabled = true, proxyTargetClass = true)
@Configuration
@ComponentScan(basePackages = "gestionprojet.java")
@PropertySource("classpath:application.properties")
@Import({PersistenceJPAConfig.class, WebSecurityConfig.class})
public class WebConfig extends WebMvcConfigurerAdapter {...}
OP 实际上找到了一个库来强制自动装配到非 spring 管理的 bean 中,而不是重构所有代码:
该库是:https://github.com/alv-ch/alv-ch-java
可以这样使用:
public class NotificationManager {
@Autowired
private TaskScheduler scheduler;
public NotificationManager(WebSocketMessage webSocketMessage, String userName, Date date, Date time) {
AutowireHelper.autowire(this, scheduler);
scheduleTask(webSocketMessage, userName, combine(date,time));
}
...
}
这会将
TaskScheduler
自动连接到 NotificationManager
,即使它不是 spring 管理的。
您可以在这里查看 AutowireHelper 源代码。
@Service
public class NotificationManager {
@Autowired
private TaskScheduler scheduler;
private ScheduledFuture<?> sc;
public void scheduleTask(WebSocketMessage webSocketMessage, String userName, Date date, Date time) {
scheduleTask(webSocketMessage, userName, combine(date,time));
}
public void scheduleTask(WebSocketMessage webSocketMessage, String userName, Date startTime)
{
Runnable r = new NotificationSenderTask(webSocketMessage, userName);
sc = scheduler.schedule(r, new Date());
}
}
然后,在您以前执行
NotificationManager mn = new NotificationManager(...)
的位置,执行以下操作:
@Autowired
private NotificationManager notificationManager;
...
notificationManager.scheduleTask(new WebSocketMessage(n), user.getEmail(),date1,date2);
为了使其工作,无论它在哪里,它也需要位于 spring 管理的 bean 内。
你还没有初始化全局实例变量
私有TaskScheduler调度程序;
由于它是一个全局实例变量,因此不会给出任何编译时错误,并且隐式地使用 null 值进行初始化。
这就是为什么当你尝试访问scheduler.schedule时它会抛出空指针错误。
希望这能解决您的疑问。