为什么静态值不同于appender（log4j custom appender）？

Question

我在 spring.

中创建了这样的静态变量

public class A {
  private static final Map<String, Session> listMap = new HashMap<>();
  public static Map<String> getMap() { return this.listMap.values() }
  public static void addMap(String name, Session s) { return this.listMap.put(name, s) }
}

我保存在服务层

@Slf4j
public class BService {
  public void addSession(String name, Session s) { 
    A.addMap("a", s);
    log.info("added!");
  }
}

保存后，我在自定义appender中使用它。(https://www.baeldung.com/log4j2-custom-appender)

@Plugin(
  name = "MapAppender", 
  category = Core.CATEGORY_NAME, 
  elementType = Appender.ELEMENT_TYPE)
public class MapAppender extends AbstractAppender {

    private ConcurrentMap<String, LogEvent> eventMap = new ConcurrentHashMap<>();

    protected MapAppender(String name, Filter filter) {
        super(name, filter, null);
    }

    @PluginFactory
    public static MapAppender createAppender(
      @PluginAttribute("name") String name, 
      @PluginElement("Filter") Filter filter) {
        return new MapAppender(name, filter);
    }

    @Override
    public void append(LogEvent event) {
        Map<> resultMap = A.getMap();
        send()
    }
}

然而，当appender的append()方法被执行时，A.getMap() return nothing(size 0)。（A.getMap() return 在服务层正确。）为什么静态值不一样？..

Answer 1

listMap在你调用addSession时被加载所以它是空的当append()方法被调用时

为什么静态值不同于appender（log4j custom appender）？

Why is the static value different from appender(log4j custom appender)?

java

static

log4j

appender

spring-boot