trivial: extracted POST string constant

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/fileupload/trunk@1455456 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/src/main/java/org/apache/commons/fileupload/servlet/ServletFileUpload.java b/src/main/java/org/apache/commons/fileupload/servlet/ServletFileUpload.java
index cd0cafd..4c7cf87 100644
--- a/src/main/java/org/apache/commons/fileupload/servlet/ServletFileUpload.java
+++ b/src/main/java/org/apache/commons/fileupload/servlet/ServletFileUpload.java
@@ -45,6 +45,8 @@
  */
 public class ServletFileUpload extends FileUpload {
 
+    private static final String POST_METHOD = "post";
+
     // ---------------------------------------------------------- Class methods
 
     /**
@@ -58,7 +60,7 @@
      */
     public static final boolean isMultipartContent(
             HttpServletRequest request) {
-        if (!"post".equals(request.getMethod().toLowerCase())) {
+        if (!POST_METHOD.equals(request.getMethod().toLowerCase())) {
             return false;
         }
         String contentType = request.getContentType();