新增注释，方便理解

proxy-common/src/main/java/org/fengfei/lanproxy/common/container/ContainerHelper.java

@@ -13,7 +13,7 @@ import org.slf4j.LoggerFactory;
  */
 public class ContainerHelper {
 
-    private static Logger logger = LoggerFactory.getLogger(ContainerHelper.class);
+    private static Logger LOGGER = LoggerFactory.getLogger(ContainerHelper.class);
 
     private static volatile boolean running = true;
 
@@ -25,7 +25,7 @@ public class ContainerHelper {
 
         // 启动所有容器
         startContainers();
-
+        //在JVM销毁前执行的一个线程
         Runtime.getRuntime().addShutdownHook(new Thread() {
 
             @Override
@@ -53,20 +53,20 @@ public class ContainerHelper {
 
     private static void startContainers() {
         for (Container container : cachedContainers) {
-            logger.info("starting container [{}]", container.getClass().getName());
+            LOGGER.info("starting container [{}]", container.getClass().getName());
             container.start();
-            logger.info("container [{}] started", container.getClass().getName());
+            LOGGER.info("container [{}] started", container.getClass().getName());
         }
     }
 
     private static void stopContainers() {
         for (Container container : cachedContainers) {
-            logger.info("stopping container [{}]", container.getClass().getName());
+            LOGGER.info("stopping container [{}]", container.getClass().getName());
             try {
                 container.stop();
-                logger.info("container [{}] stopped", container.getClass().getName());
+                LOGGER.info("container [{}] stopped", container.getClass().getName());
             } catch (Exception ex) {
-                logger.warn("container stopped with error", ex);
+                LOGGER.warn("container stopped with error", ex);
             }
         }
     }