java 下载功能

Posted 2023-03-17

参考技术A 下载功能实际上就是将远程服务器的文件流通过ftp功能转换为本地文件流进行存储。举例：
/**
*下载并解压文件
*
* @param localFilePath
* @param fileName
* @param routeFilepath
* @return
* @throws Exception
*/
public static String fileDownloadByFtp(String localFilePath, String fileName,String routeFilepath) throws Exception
FileInputStream fis = null;
ByteArrayOutputStream bos = null;
FileOutputStream fos = null;
FTPClient ftpClient = new FTPClient();
String SFP = System.getProperty("file.separator");
String bl = "false";
try
Log.info("下载并解密文件开始");
Log.info("连接远程下载服务器"+CCFCCBUtil.CCFCCBHOSTNAME+":"+22);
ftpClient.connect(CCFCCBUtil.CCFCCBHOSTNAME, 22);
ftpClient.login(CCFCCBUtil.CCFCCBLOGINNAME, CCFCCBUtil.CCFCCBLOGINPASSWORD);

FTPFile[] fs;

ftpClient.makeDirectory(routeFilepath);
ftpClient.changeWorkingDirectory(routeFilepath);
bl = "false";
fs = ftpClient.listFiles();
for (FTPFile ff : fs)
if (ff.getName().equals(fileName))
bl = "true";
Log.info("下载文件开始。");
ftpClient.setBufferSize(1024);
// 设置文件类型（二进制）
ftpClient.setFileType(FTPClient.BINARY_FILE_TYPE);
InputStream is = ftpClient.retrieveFileStream(fileName);
bos = new ByteArrayOutputStream(is.available());
byte[] buffer = new byte[1024];
int count = 0;
while ((count = is.read(buffer)) != -1)
bos.write(buffer, 0, count);

bos.flush();
fos = new FileOutputStream(localFilePath+SFP+fileName);
fos.write(bos.toByteArray());
Log.info("下载文件结束："+localFilePath);


Log.info("检查文件是否存："+fileName+" "+bl);
if("false".equals(bl))
ViewUtil.dataSEErrorPerformedCommon("查询无结果，请稍后再查询。");
return bl;

return bl;
catch (Exception e)
throw e;
finally
if (fis != null)
try
fis.close();
catch (Exception e)
Log.info(e.getLocalizedMessage(), e);


if (bos != null)
try
bos.close();
catch (Exception e)
Log.info(e.getLocalizedMessage(), e);


if (fos != null)
try
fos.close();
catch (Exception e)
Log.info(e.getLocalizedMessage(), e);




备注：只需要修改 ftpClient.connect方法中的用户名和密码即可进行远程服务器连接下载，具体的根据实际情况修改即可。

java实现下载附件功能

前台js方法：

//下载为Excel
function downResult() 
    
      var url = $ctx/downResult.do;
      var fileName = "稽核结果.xlsx";
      var form = $("<form></form>").attr("action", url).attr("method", "post");
      form.append($("<input></input>").attr("type", "hidden").attr("name", "fileName").attr("value", fileName));
      form.appendTo(body).submit().remove();

后台controller方法(这里下载的类型是Excel，下载其他文件需要修改类型)：

@ResponseBody
    @RequestMapping(value="downResult.do")
    public ModelAndView downResult(HttpServletRequest request,
                              HttpServletResponse response)throws Exception
        
        URL url = getClass().getClassLoader().getResource("auditResult.xls");
        String path = url.getPath();
        //downloadFile(request,response, path, "auditResult.xlsx");
        down(request,response, path, "auditResult.xlsx");
        
        return null;
    

    private void down(HttpServletRequest request, HttpServletResponse response, String path,String fileName) throws Exception 
          java.io.BufferedInputStream bis = null;
          java.io.BufferedOutputStream bos = null;
          try 
           String agent = request.getHeader("User-Agent");
           boolean isMSIE = (agent != null && (agent.indexOf("MSIE") != -1 || agent.indexOf("Trident") != -1));

           if (isMSIE) 
            response.setHeader("Content-disposition",
              "attachment; filename=" + java.net.URLEncoder.encode(fileName, "UTF8"));
            else 
            response.setHeader("Content-disposition",
              "attachment; filename=" + new String(fileName.getBytes("utf-8"), "ISO8859-1"));
           
           response.setContentType("application/x-xls");

           
           bis = new java.io.BufferedInputStream(new java.io.FileInputStream(path));
           bos = new java.io.BufferedOutputStream(response.getOutputStream());
           byte[] buff = new byte[2048];
           int bytesRead;
           while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) 
            bos.write(buff, 0, bytesRead);
           
          catch(Exception e) 
           /*operResult.setResult("fail");
           operResult.setMsg("操作失败:"+e.getMessage());*/
              e.printStackTrace();
          finally 
           if (bis != null)
            bis.close();
           if (bos != null)
            bos.close();