从FTP上下载文件并打成ZIP包给用户下载

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  //从FTP上下载文件并打成ZIP包给用户下载   
  FTPClient ftpClient = null;   
        ZipOutputStream zipOut = null;   
  
        try {   
            // 创建ftp连接对象   
            ftpClient = new FTPClient();   
            ftpClient.connect(FtpContants.FTP_IP, FtpContants.FTP_PORT);   
            // 登陆ftp服务器   
            ftpClient.login(FtpContants.FTP_USERNAME, FtpContants.FTP_PWD);   
            // 设置文件的传输类型，默认是ASCII，修改为二进制   
            ftpClient.setFileType(FTP.BINARY_FILE_TYPE);   
            // printWorkingDirectory是用户的工作目录   
            String basePath = ftpClient.printWorkingDirectory() + "/download/data";   
            // 切换到指定目录中，如果切换失败说明目录不存在   
            boolean boo = ftpClient.changeWorkingDirectory(basePath);   
            // 如果切换路径失败，说明拼接的路径有问题，抛出异常   
            if (!boo) {   
                LogUtil.printErrorLog("the directory does not exist ,"  
                        + "or the user don't hava the enterence to this directory " + basePath);   
                return;   
            }   
  
            // 这个方法的意思就是每次数据连接之前,ftp client告诉ftp server开通一个端口来传输数据   
            ftpClient.enterLocalPassiveMode();   
            // 遍历路径下的所有文件   
            FTPFile[] fileList = ftpClient.listFiles();   
  
            response.reset();   
            // 设置导出文件头   
            response.setContentType("application/octet-stream");   
            response.setHeader("Content-Disposition",   
                    "attachment;filename=" + new String(zipFileName.getBytes(LANGUE_GBK), LANGUE_ISO));   
            // 定义Zip输出流   
            zipOut = new ZipOutputStream(response.getOutputStream());   
  
            byte[] byteReader = new byte[BYTE_INIT_SIZE];   
            ByteArrayOutputStream os = null;   
            for (FTPFile tempFile : fileList) {   
                if (tempFile.isFile()) {   
                    os = new ByteArrayOutputStream();   
                    String downFileName = new String(tempFile.getName().getBytes(LANGUE_GBK), LANGUE_ISO);   
                    // 从FTP上下载downFileName该文件把该文件转化为字节数组的输出流   
                    ftpClient.retrieveFile(downFileName, os);   
                    byte[] bytes = os.toByteArray();   
                    InputStream ins = new ByteArrayInputStream(bytes);   
  
                    int len;   
                    zipOut.putNextEntry(new ZipEntry(tempFile.getName()));   
                    // 读入需要下载的文件的内容，打包到zip文件   
                    while ((len = ins.read(byteReader)) > 0) {   
                        zipOut.write(byteReader, 0, len);   
                    }   
                }   
            }   
            zipOut.flush();   
        } catch (IOException e) {   
            LogUtil.printErrorLog(e.getMessage());     
        } finally {   
            // 关闭ftp连接   
            if (null != ftpClient) {   
                try {   
                    ftpClient.disconnect();   
                } catch (IOException e) {   
                    LogUtil.printErrorLog("close Ftp connection error :" + e.getMessage());   
                }   
            }   
            // 关闭zip文件输出流   
            if (null != zipOut) {   
                try {   
                    zipOut.closeEntry();   
                    zipOut.close();   
                } catch (IOException e) {   
                    LogUtil.printErrorLog("close ZipOutputStream connection error :" + e.getMessage());   
                }   
            }   
        }