关于struts2 批量下载文件，代码写好了，但是出现异常，严重: Can not find a java.io.InputStream with the na
麻烦大家帮我看看，在网上搜索了一下，但是都没有结果！
action代码：
  package cn.edu.cuit.disasterSystem.web.struts2.action;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.text.SimpleDateFormat;
import java.util.Date;


import org.apache.struts2.ServletActionContext;
import org.apache.tools.zip.ZipEntry;
import org.apache.tools.zip.ZipOutputStream;

import com.opensymphony.xwork2.ActionSupport;


@SuppressWarnings("serial")
public class DownloadAction extends ActionSupport {

  private String filenames;
  private String filepaths;
  private String[] filenameArray = null;
  private String[] filepathArray = null;
  private String filename;
  private String filepath;
  private SimpleDateFormat format = new SimpleDateFormat("yyyyMMddHHmmss");
   
   
 
  public String getFilenames() {
  return filenames;
  }
 
  public void setFilenames(String filenames) {
  this.filenames = filenames;
  if (this.filenames.contains("|")) {
  parseFilenamesToArray();
  }
  }
 
  public String getFilepaths() {
  return filepaths;
  }

  public void setFilepaths(String filepaths) {
  this.filepaths = filepaths;
  if (this.filepaths.contains("|")) {
  parseFilepathsToArray();
  }
  }
   
  public void parseFilenamesToArray() {
  filenameArray = filenames.split("\\|");
  }

  public void parseFilepathsToArray() {
  filepathArray = filepaths.split("\\|");
  }
   
  
  public String getFilename() {
  try {
  return new String(filename.getBytes(), "ISO-8859-1");
  } catch (UnsupportedEncodingException e) {
  e.printStackTrace();
  return filename;
  }
  }
   
   

  public String getFilepath(){
  return filepath;
  }

  public void initFilename() {
  if(isBaleZip()){
  this.filename = "批量打包下载.zip";
  }else{
  this.filename = getFilenames();
  }
  System.out.println("下载文件名: "+filename);
  }
   
  public void initFilepath() {
  if(isBaleZip()){
  String rootpath = ServletActionContext.getServletContext().getRealPath("/upload/temp");
  String requestip = ServletActionContext.getRequest().getLocalAddr();
  //this.filepath = "c:\\批量打包下载.zip";
  this.filepath = rootpath+"\\"+requestip+"-"+format.format(new Date())+".zip";
  }else{