!299 XssHttpServletRequestWrapper中增加available方法

Merge pull request !299 from Ming/master

@@ -63,7 +63,8 @@ public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper
 
         // xss过滤
         json = EscapeUtil.clean(json).trim();
-        final ByteArrayInputStream bis = new ByteArrayInputStream(json.getBytes("utf-8"));
+        byte[] jsonBytes = json.getBytes("utf-8");
+        final ByteArrayInputStream bis = new ByteArrayInputStream(jsonBytes);
         return new ServletInputStream()
         {
             @Override
@@ -79,6 +80,11 @@ public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper
             }
 
             @Override
+            public int available() throws IOException {
+                return jsonBytes.length;
+            }
+
+            @Override
             public void setReadListener(ReadListener readListener)
             {
             }