ajax4jsf跟outputStream.write冲突?

ajax4jsf跟outputStream.write冲突?

我在项目中引入ajax4jsf框架
web.xml中加入

  < filter >
         < display-name > Ajax4jsf Filter </ display-name >
         < filter-name > ajax4jsf </ filter-name >
         < filter-class > org.ajax4jsf.Filter </ filter-class >
   </ filter >
   < filter-mapping >  
       < filter-name > ajax4jsf </ filter-name >
       < servlet-name > Faces Servlet </ servlet-name >
       < dispatcher > REQUEST </ dispatcher >
       < dispatcher > FORWARD </ dispatcher >
       < dispatcher > INCLUDE </ dispatcher >
  </ filter-mapping >

结果以前的输出文件到客户端的代码就出问题了

                InputStream fileInputStream  =  mgt.downloadToStream(result_pathEl.getTextTrim());
                mgt.deleteFile(result_pathEl.getTextTrim()); // 删除临时的报表文件
                JSFUtil.setSessionAttribute(sessionId,  " true " );
                 if ( fileInputStream  ==   null  ) {
                  System.out.println("==========get inputstream is null========");
                }

                OutputStream o  =  response.getOutputStream();
                response.reset();
                response.setContentType(  " APPLICATION/OCTET-STREAM "  );
                response.setHeader(  " Content-Disposition " ,  " attachment;filename=\ ""  +  " exportExcel.xls " +  " \ ""  );

                 int  length;
                 byte  buf[]  =   new   byte [ 1024 ];

                 while  ( ( length  =  fileInputStream.read( buf,  0 ,  1024  ) )  !=   - 1  )  {
                    o.write( buf, 0, length );
                }
                o.flush();
                o.close();
                fileInputStream.close();

提示错误如下：主要是o.write出问题

java.lang.NullPointerException
        at org.ajax4jsf.framework.ajax.xmlfilter.FilterServletResponseWrapper$By
teArrayServletOutputStream.write(FilterServletResponseWrapper.java:290)

把web.xml中的ajax4jsf的filter给去掉后，一切又恢复正常

有那位仁兄遇到同样情况的吗？