业务场景：

从A服务器通过SFTP将文件下载到应用服务器B，需要将文件从应用服务器B下载到用户本地(文件和应用都在B服务器)

想法：

1. 想要通过FTP连接B服务器下载，但是FTP只能下载到应用所在的本地，也就是只能下载到下载到B服务器，无法下载到用户本地。

2. 通过普通的下载方式，用文件流通过response下载，但是文件夹内有多个文件，无法同时下载

实现：

采用将多个文件打包下载

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

//通过工号和日期去获取相应的文件夹路径

String usercode = request.getParameter("usercode");

String date = request.getParameter("date");

String formPath = "/tmp/ENongXian/"+usercode+"/"+date;

//遍历这个路径下的所有文件名

List fileNames = this.getFileName(formPath);

//如果找不到文件 返回not found file

if(fileNames == null||fileNames.size()==0){

PrintWriter out = response.getWriter();

response.setContentType("text/html; charset=GBK");//注意text/html，和application/html

out.print("

");

out.flush();

out.close();

}else{

//开始批量压缩下载

ZipOutputStream zos = new ZipOutputStream(response.getOutputStream());

response.setContentType("APPLICATION/OCTET-STREAM");

response.setHeader("Content-Disposition","attachment; filename="+this.getZipFilename());

System.out.println("in BatchDownload................");

File[] files = new File[fileNames.size()];

for(int i=0;i

String filename = fileNames.get(i).toString();

files[i] = new File(formPath+"/"+filename);

}

将文件进行压缩

zipFile(files, "", zos);

zos.flush();

zos.close();

}

}

private void zipFile(File[] subs, String baseName, ZipOutputStream zos) throws IOException {

for (int i=0;i

File f=subs[i];

zos.putNextEntry(new ZipEntry(baseName + f.getName()));

FileInputStream fis = new FileInputStream(f);

byte[] buffer = new byte[1024];

int r = 0;

while ((r = fis.read(buffer)) != -1) {

zos.write(buffer, 0, r);

}

fis.close();

}

}

private String getZipFilename(){

Date date=new Date();

String s=date.getTime()+".zip";

return s;

}

public List getFileName(String filePath){

File file = new File(filePath);

List fileNameList = new ArrayList();

File[] fileList = file.listFiles();

if(fileList == null || fileList.length ==0){

return null;

}

for(int i=0;i

if("txt".equals(fileList[i].getName().substring(fileList[i].getName().lastIndexOf(".") + 1))){

continue;

}

if(fileList[i].isFile()){

String fileName = fileList[i].getName();

fileNameList.add(fileName);

}

}

return fileNameList;

}