Spring拦截器读取响应OutputStream

Question

Inside spring controller writes an excel stream into response

     HSSFWorkbook workbook = getWorkbook();
     OutputStream out = response.getOutputStream();     
     response.setHeader("pragma", "public");
     response.setHeader("Cache-Control", "public");
     response.setContentType("application/vnd.ms-excel");      
     response.setHeader("Content-Disposition", "attachment;filename=sampleexcel.xls");      
     workbook.write(out);        
     out.close();
     // response.flushBuffer();

As per this link How to read and copy the HTTP servlet response output stream content for logging implementated responsewrapper. Below is Interceptor code,

      public void afterCompletion(HttpServletRequest request,
            HttpServletResponse response, Object handler, Exception ex)
            throws Exception {

       HttpServletResponseCopier resp=  new HttpServletResponseCopier(response) ;         
       byte[] responseData = resp.getCopy();            
        System.out.println("length "+responseData.length); // its 0 bytes

    }

Basically want to read the Outputstream contents into a temp file. Then add encryption information in it. Finally write this encrypted file into response stream. In above code,resp.getCopy() is empty,hence it writes 0 bytes into temp file.

Any pointers what is wrong.Is there alternate way to do achive this.

Spring 3.1, JDK 1.7

Answer 1

Oups, a spring-mvc interceptor is not a filter. It provides hooks to be called before controller execution, after controller execution and after view generation, but cannot replace the response.

The filter used in the referenced post actually replace the response with a wrapper so that everything that is written to the response actually goes into the wrapper and is processed at the time it is written. Here you only create the wrapper once everything has been written so it can only intercept... nothing.

You will have to implement a filter and a custom response wrapper to achieve your goal.