isNumber update

src/main/java/com/alibaba/druid/sql/parser/Lexer.java

@@ -16,6 +16,7 @@
 package com.alibaba.druid.sql.parser;
 
 import com.alibaba.druid.util.StringUtils;
+import org.apache.commons.lang.math.NumberUtils;
 
 import static com.alibaba.druid.sql.parser.CharTypes.isFirstIdentifierChar;
 import static com.alibaba.druid.sql.parser.CharTypes.isIdentifierChar;
@@ -1150,7 +1151,7 @@ public class Lexer {
 
     public BigDecimal decimalValue() {
         String value = subString(mark, bufPos);
-        if (!StringUtils.isNumeric(value)){
+        if (!NumberUtils.isNumber(value)){
             throw new ParserException(value+" is not a number!");
         }
         return new BigDecimal(value.toCharArray());

src/main/java/com/alibaba/druid/util/StringUtils.java

@@ -119,18 +119,4 @@ public class StringUtils {
         }
         return h;
     }
-
-    public static boolean isNumeric(final CharSequence cs) {
-        if (isEmpty(cs)) {
-            return false;
-        }
-        final int sz = cs.length();
-        for (int i = 0; i < sz; i++) {
-            if (!Character.isDigit(cs.charAt(i))) {
-                return false;
-            }
-        }
-        return true;
-    }
-
 }