perf：空指针调整

springboot-util/src/main/java/com/tiesheng/util/ServletKit.java

@@ -23,6 +23,21 @@ public class ServletKit extends ServletUtil {
         return null;
     }
 
+
+    /**
+     * 获取请求头
+     *
+     * @param name 请求头
+     * @return 请求头
+     */
+    public static String getHeader(String name) {
+        HttpServletRequest request = getRequest();
+        if (request == null) {
+            return "";
+        }
+        return getHeader(request, name, "utf-8");
+    }
+
     /**
      * 获取客户端IP
      *

springboot-util/src/main/java/com/tiesheng/util/service/TsCacheService.java

@@ -84,7 +84,7 @@ public class TsCacheService {
      * 验证 图片验证码
      */
     public void verifyCaptcha(String value) {
-        String captchaKey = ServletUtil.getHeader(ServletKit.getRequest(), "captcha", "utf-8");
+        String captchaKey = ServletKit.getHeader("captcha");
         String cache = get(captchaKey);
         if (StrUtil.isEmpty(cache) || !StrUtil.equals(cache, value)) {
             throw new ApiException("验证码不正确");