diff --git a/src/main/java/com/kimgo/wepush/model/SMSInfo.java b/src/main/java/com/kimgo/wepush/model/SMSInfo.java
index 46dc914..05213a8 100644
--- a/src/main/java/com/kimgo/wepush/model/SMSInfo.java
+++ b/src/main/java/com/kimgo/wepush/model/SMSInfo.java
@@ -24,16 +24,12 @@ public class SMSInfo {
      * @return 如果所有字段都非空，则返回 true，否则返回 false。
      */
     public boolean validateFields() {
-        return StringUtils.isNotBlank(smsNumber) &&
-                StringUtils.isNotBlank(smsAcceptanceTime) &&
-                StringUtils.isNotBlank(smsContent);
+        return isNotBlankAndNotLiteralNull(smsNumber) &&
+                isNotBlankAndNotLiteralNull(smsAcceptanceTime) &&
+                isNotBlankAndNotLiteralNull(smsContent);
     }
-    public boolean isNullString(){
-        String nullString = "null";
-        if (this.smsNumber.equals(nullString) || this.smsContent.equals(nullString) || this.smsAcceptanceTime.equals(nullString)){
-            logger.info("SMSInfo has null String.");
-            return true;
-        }
-        return false;
+
+    private boolean isNotBlankAndNotLiteralNull(String value) {
+        return StringUtils.isNotBlank(value) && !"null".equals(value);
     }
 }
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