smartupload能在weblogic下使用吗？

Question

我用的是JBUILDER+WEBLOGIC
用smartupload老是报错
   java.lang.StringIndexOutOfBoundsException: String index out of range: -1
at java.lang.String.substring(String.java:1480)
at weblogic.servlet.internal.ChunkOutputWrapper.print(ChunkOutputWrapper.java:132)
at weblogic.servlet.jsp.JspWriterImpl.print(JspWriterImpl.java:273)我在JSP代码是
  <%@ page contentType="text/html;charset=gb2312"
import="com.jspsmart.upload.*" %>
<%
SmartUpload su = new SmartUpload();
su.initialize(pageContext);
su.setContentDisposition(null);
su.downloadFile("/bb.txt");
%>