Java從網上下載文件的代碼

DownLoadUtil.java

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);
    /**

 * 下載文件
 * @param name 用戶下載的文件名(*****.***)
 * @param filePath 文件路徑
 * @param response 
 * @param fileType 文件類型
 * @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);
    //設置文件類型
    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];// 緩沖區
    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, 0, 4096)) > -1) {
            output.write(buffer, 0, 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;
}

}</pre> 

 調用 DownLoadUtil.java;
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;    //服務器上文件名
    fileName = "xxxl.xls";
    name = "xxxx.xls";
  }
  String filePath = path + System.getProperty("file.separator") + fileName;
  DownLoadUtil.downLoadFile(name,filePath, response, "xls");
  return null;
 }