diff --git a/jero-boot/jero-boot-base/jero-boot-base-core/src/main/java/com/jero/config/CsrfFilter.java b/jero-boot/jero-boot-base/jero-boot-base-core/src/main/java/com/jero/config/CsrfFilter.java
index 2ce5432a..1a7de7fd 100644
--- a/jero-boot/jero-boot-base/jero-boot-base-core/src/main/java/com/jero/config/CsrfFilter.java
+++ b/jero-boot/jero-boot-base/jero-boot-base-core/src/main/java/com/jero/config/CsrfFilter.java
@@ -7,15 +7,12 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.stereotype.Component;
-import org.springframework.util.ResourceUtils;
 
 import javax.servlet.*;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
-import java.io.*;
+import java.io.PrintWriter;
 import java.text.SimpleDateFormat;
-import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Date;
 import java.util.List;
 
@@ -28,6 +25,8 @@ import java.util.List;
 
 @Component
 public class CsrfFilter implements Filter {
+
+    private static final String UNKNOWN_CONSTANT = "unknown";
     /**
      * LOGGER
      */
@@ -106,13 +105,13 @@ public class CsrfFilter implements Filter {
      */
     public  String getIp(HttpServletRequest request) {
         String ip = request.getHeader("x-forwarded-for");
-        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
+        if (ip == null || ip.length() == 0 || UNKNOWN_CONSTANT.equalsIgnoreCase(ip)) {
             ip = request.getHeader("Proxy-Client-IP");
         }
-        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
+        if (ip == null || ip.length() == 0 || UNKNOWN_CONSTANT.equalsIgnoreCase(ip)) {
             ip = request.getHeader("WL-Proxy-Client-IP");
         }
-        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
+        if (ip == null || ip.length() == 0 || UNKNOWN_CONSTANT.equalsIgnoreCase(ip)) {
             ip = request.getRemoteAddr();
         }
         if (ip.equals("0:0:0:0:0:0:0:1")) {
@@ -122,6 +121,6 @@ public class CsrfFilter implements Filter {
     }
     @Override
     public void destroy() {
-
+        // do other
     }
 }