java - How to substitute HttpServletResponse output stream? -

i need use jsp generate html report. made example, not work in tomcat6 far.

public class substitutionservlet extends httpservlet {     @override     protected void service(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {         requestdispatcher dispatcher = request.getrequestdispatcher("/web-inf/jsp/report.jsp");         final bytearrayoutputstream buf = new bytearrayoutputstream();         servletresponsewrapper wrapper = new httpservletresponsewrapper(response){             @override             public printwriter getwriter() throws ioexception {                 return new printwriter(buf);             }         };         dispatcher.forward(request, wrapper);         string html = buf.tostring("utf-8"); // "" returned         system.out.println(html);         response.getoutputstream().print("completed");     } } 

when try run example, empty string result. mistake have made?

the problem creating new printwriter every invocation of method getwriter. instead should have 1 , reuse it.

public class substitutionservlet extends httpservlet {  private static final long serialversionuid = 1l;  @override  protected void service(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {      requestdispatcher dispatcher = request.getrequestdispatcher("/web-inf/jsp/report.jsp");      final bytearrayoutputstream buf = new bytearrayoutputstream();      final printwriter out = new printwriter(buf); //create 1 writer      servletresponsewrapper wrapper = new httpservletresponsewrapper(response) {          @override          public printwriter getwriter() throws ioexception {              return out; // reuse writer          }      };      dispatcher.forward(request, wrapper);      string html = buf.tostring("utf-8"); // "" returned      system.out.println(html);      response.getoutputstream().print("completed");    } }