¿Cómo escribir en un objeto de respuesta HttpServletResponse?

Question

que tienen esta clase de acción, esta clase se encarga de mi respuesta

actualización ahora pasa respuesta de DownloadStatus clase, pero parece que es nula

public final class DownloadStatus extends ActionSupport implements ServletRequestAware,ServletResponseAware 
{ 
    static Logger logger = Logger.getLogger(DownloadStatus.class); 
    private HttpServletRequest request; 
    private HttpServletResponse response; 
    private File cfile; 
    private String cfileFileName; 

    @Override 
    public String execute() 
    { 

     logger.debug("Inside DownloadStatus.execute method") 

     try { 
      ChainsInvoker invoker = new ChainsInvoker() 
      def executionResponse = invoker.invoke(request, MYChains.download, cfile, cfileFileName) 
      if(executionResponse == null || ErrorHandler.checkIfError(executionResponse)) 
      { 
       return ERROR 
      } 
      response.setContentType("APPLICATION/xml") 

      logger.debug("filename: $cfileFileName") 

      response.addHeader("Content-Disposition", "attachment; filename=\""+cfileFileName+"\"") 
      response.getWriter().print(executionResponse) 
      logger.debug("executionResponse :" + executionResponse) 
      invoker.invoke(MYChains.clean) 
     }catch (Exception exp) { 

      logger.error("Exception while Creating Status ") 
      logger.error(exp.printStackTrace()) 

     } 
     return NONE 
    } 

    @Override 
    public void setServletRequest(HttpServletRequest request) {  this.request = request; } 

    @Override 
    public void setServletResponse(HttpServletResponse response) {  this.response = response; } 

    public File getcfile() {  cfile } 

    public void setcfile(File cfile) {  this.cfile = cfile } 

    public String getcfileFileName() {  cfileFileName } 

    public void setcfileFileName(String cfileFileName){  this.cfileFileName = cfileFileName } 
} 

y por debajo de la clase de escribir corriente en respuesta

class DownloadStatusResponse implements Command { 

static Logger logger = Logger.getLogger(DownloadStatusResponse.class); 
@Override 
public boolean execute(Context ctx) throws Exception 
{ 
    logger.debug("Inside DownloadStatusResponse.execute() method") 
    OutputStream response = null; 

    if(ctx.get(ContextParams.absFileName) != null && ctx.get(ContextParams.absFileName).toString().trim().length() != 0) 
    { 
HttpServletResponse resp = ctx.get(ContextParams.response) 
/*I am trying to get Response here*/ 

     response=downloadStatusFile(ctx.get(ContextParams.absFileName).toString(),resp) 
    } 

    logger.debug("Response: " + response) 
    ctx.put(ContextParams.response,response); /*ContextParams is a enum of keywords, having response*/ 
    return false; 
} 

private OutputStream downloadStatusFile(String filename,HttpServletResponse resp) 
{ 
    logger.info("Inside downloadStatusFile() method") 

    File fname = new File(filename) 
    if(!fname.exists()) 
    { 
     logger.info("$filename does not exists") 
     return null 
    } 
    else 
    { 

     resp.setContentType("APPLICATION/xml") 
/*Exception: cannot setContentType on null object*/ 

     resp.addHeader("Content-Disposition", "attachment; filename=\""+fname.getName()+"\"") 

     FileInputStream istr = new FileInputStream(fname) 
     OutputStream ostr = resp.getOutputStream() 
     /*I need to use resp.getOutputStream() for ostr*/ 

     int curByte=-1; 

     while((curByte=istr.read()) !=-1) 
      ostr.write(curByte) 

     ostr.flush();   
    }    
    return ostr 
} 

} 

Mi pregunta es ¿cómo se puede ostr ser devuelto a la response en DownloadStatus clase?

Update (trabajo servlet de prueba)

tengo esta por debajo de servlet, que hace el trabajo de conseguir el contenido del archivo en una corriente y dando vuelta a la HttpServletResponse, pero yo quiero usarlo en el código

anteriormente

public class DownloadServlet extends HttpServlet { 


public void doGet(HttpServletRequest req, HttpServletResponse resp) 
throws ServletException, IOException { 

    String fileName = req.getParameter("zipFile"); 

    if(fileName == null)  return; 

     File fname = new File(fileName); 
     System.out.println("filename"); 
     if(!fname.exists()) {System.out.println("Does not exists");   return;} 

     FileInputStream istr = null; 
     OutputStream ostr = null; 
     //resp.setContentType("application/x-download"); 
     resp.setContentType("APPLICATION/ZIP"); 
     resp.addHeader("Content-Disposition", "attachment; filename=\""+fname.getName()+"\""); 
     System.out.println(fname.getName()); 
     try { 
      istr = new FileInputStream(fname); 
      ostr = resp.getOutputStream(); 
      int curByte=-1; 

       while((curByte=istr.read()) !=-1) 
        ostr.write(curByte); 

      ostr.flush(); 
     } catch(Exception ex){ 
      ex.printStackTrace(System.out); 
     } finally{ 
      try { 
      if(istr!=null) istr.close(); 
      if(ostr!=null) ostr.close(); 
      } catch(Exception ex){ 

       ex.printStackTrace(); 
      System.out.println(ex.getMessage()); 
      } 
     } 
     try { 
      resp.flushBuffer(); 
     } catch(Exception ex){ 
      ex.printStackTrace(); 
      System.out.println(ex.getMessage()); 
     } 
    } 
} 

Answer 1

Por lo que yo entiendo, todo lo que necesita es cómo descargar un archivo usando Struts2.

Es necesario algo como esto es su archivo struts.xml

<action name="downloadfile" class="DownloadAction"> 
      <result name="success" type="stream"> 
       <param name="contentType">application/pdf</param> 
       <param name="inputName">inputStream</param> 
       <param name="contentDisposition">attachment;filename="document.pdf"</param> 
       <param name="bufferSize">1024</param> 
      </result> 
     </action> 

Código:

public class DownloadAction extends ActionSupport { 

    private InputStream inputStream; 

    public InputStream getInputStream() { 
    return inputStream; 
    } 

    public void setInputStream(InputStream inputStream) { 
    this.inputStream = inputStream; 
    } 

    public String execute() throws FileNotFoundException { 
    String filePath = ServletActionContext.getServletContext().getRealPath("/uploads"); 
    File f = new File(filePath + "/nn.pdf"); 
    System.out.println(f.exists()); 
    inputStream = new FileInputStream(f); 
    return SUCCESS; 
    } 
}