diff --git a/src/main/java/org/bdware/server/CMHttpServer.java b/src/main/java/org/bdware/server/CMHttpServer.java
index 157d4bc..3fded33 100644
--- a/src/main/java/org/bdware/server/CMHttpServer.java
+++ b/src/main/java/org/bdware/server/CMHttpServer.java
@@ -156,8 +156,9 @@ public class CMHttpServer {
     }
 
     private static String[] parseStrAsList(String str) {
-        if (str == null)
+        if (str == null) {
             return new String[]{};
+        }
         return str.split(",");
     }
 
diff --git a/src/main/java/org/bdware/server/nodecenter/client/NodeCenterClientController.java b/src/main/java/org/bdware/server/nodecenter/client/NodeCenterClientController.java
index 77b0499..0e3df0e 100644
--- a/src/main/java/org/bdware/server/nodecenter/client/NodeCenterClientController.java
+++ b/src/main/java/org/bdware/server/nodecenter/client/NodeCenterClientController.java
@@ -383,22 +383,18 @@ public class NodeCenterClientController implements NodeCenterConn {
                             jo.get("pubKey").getAsString(), jo.get("masterAddress").getAsString());
                     NetworkManager.instance.connectToAgent(jo.get("pubKey").getAsString(), null);
                     LOGGER.info(
-                            "[CMClientController] "
-                                    + contractID
-                                    + " 查询master结果为 pubKey="
-                                    + jo.get("pubKey").getAsString()
-                                    + " 地址为"
-                                    + jo.get("masterAddress").getAsString());
+                            String.format("the master of contract %s: pubKey=%s address=%s",
+                                    contractID,
+                                    jo.get("pubKey").getAsString(),
+                                    jo.get("masterAddress").getAsString()));
                     contractID2PubKey.put(contractID, jo.get("pubKey").getAsString());
                     return jo.get("pubKey").getAsString();
                 } catch (Exception e) {
-                    e.printStackTrace();
-                    LOGGER.info("[CMClientController] " + contractID + " 查询master结果为 null");
+                    LOGGER.warn("the master of contract " + contractID + " is null! " + e.getMessage());
                 }
             }
         } catch (Exception e) {
-            e.printStackTrace();
-            LOGGER.info("[CMClientController] " + contractID + " 查询master结果为 null");
+            LOGGER.warn("the master of contract " + contractID + " is null! " + e.getMessage());
         }
         return null;
     }