Java从网上下载文件的代码

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;

import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.Logger;

public class DownLoadUtil {
    private static Logger logger = Logger.getLogger(DownLoadUtil.class);
    /**
     * 下载文件
     * @param name 用户下载的文件名(*****.***)
     * @param filePath 文件路径
     * @param response 
     * @param fileType 文件类型
     * @return
     * @throws Exception
     */
    public static boolean downLoadFile(String name,String filePath,HttpServletResponse response,String fileType)
            throws Exception {
        logger.info("start invoke downLoadFile,[filePath:"+filePath+",fileType:"+fileType+"]");
        File file = new File(filePath);
        //设置文件类型
        if("pdf".equals(fileType)){
            response.setContentType("application/pdf");
        }else if("xls".equals(fileType)){
            response.setContentType("application/msexcel");
        }else if("doc".equals(fileType)){
            response.setContentType("application/msword");
        }
        response.setHeader("Content-Disposition","attachment;filename=""
                + new String(name.getBytes("GB2312"),"ISO8859-1") + """);
        //response.setHeader("Content-Disposition","attachment;filename=""+ URLEncoder.encode(name,"UTF-8")+ """);
        response.setContentLength((int) file.length());
        byte[] buffer = new byte[4096];// 缓冲区
        BufferedOutputStream output = null;
        BufferedInputStream input = null;
        try {
            output = new BufferedOutputStream(response.getOutputStream());
            input = new BufferedInputStream(new FileInputStream(file));
            int n = -1;
            while ((n = input.read(buffer,4096)) > -1) {
                output.write(buffer,n);
            }
            output.flush();
            response.flushBuffer();
        } catch (Exception e) {
            logger.error("exception when invoke downLoadFile",e);
            throw e;
        } finally {
            if (input != null)
                input.close();
            if (output != null)
                output.close();
        }
        logger.info("end invoke downLoadFile!");
        return true;
    }
}

public ActionForward downLoadExcelModel(ActionMapping actionMapping,ActionForm actionForm,HttpServletRequest request,HttpServletResponse response) throws Exception {
  String busType = request.getParameter("busType");
  String path = request.getSession().getServletContext().getRealPath(
    "/resources");
  String name = null;        
  String fileName = null;    //服务器上文件名
    fileName = "xxxl.xls";
    name = "xxxx.xls";
  }
  String filePath = path + System.getProperty("file.separator") + fileName;
  DownLoadUtil.downLoadFile(name,filePath,response,"xls");
  return null;
 }