JavaWeb响应下载功能实例代码（包含工具类）

<a href = "${pageContext.request.contextPath }/user/courseTab">模板下载</a>

@Controller@RequestMapping("/user")public class UploadController {@RequestMapping(value="/courseTab",method=RequestMethod.GET)  public void courseTab(HttpServletResponse response,HttpServletRequest request) throws IOException{    String path = request.getSession().getServletContext().getRealPath("/courseTab/课表上传模板.xls");    DownUtil.downMb(response, path, "课表模板"+DateFormat.formatSimple(new Date()));}}

package org.cxxy.base.cxsc.util;import java.io.BufferedInputStream;import java.io.BufferedOutputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.UnsupportedEncodingException;import javax.servlet.http.HttpServletResponse;/** * @Title: DownUtil.java * @Package org.cxxy.base.cxsc.util * @Description:文件下载工具类 * @author ChoviWu * @date 2017年6月18日 下午2:44:17 * @version V1.0 */public class DownUtil {  /**   *   * @Description:   * @param @param response   * @param @param url 文件在数据库的路径   * @param @param base 文件存放的基础路径   * @param @param folderPath 上传所在的文件夹   * @param @return   * @param @throws IOException   * @return int   * @throws   */  @SuppressWarnings("unused")  public static int downFile(HttpServletResponse response, String url,      Integer down, String base, String folderPath) throws IOException {    // 文件的名称    String fileName = url.split("/")[1];    System.out.println(fileName);    // 文件的后缀    String last = url.substring(url.lastIndexOf(".") + 1);    System.out.println(last);    // 文件路径    String downFilePath = base + folderPath + fileName;    Long fileLength = new File(downFilePath).length();// 文件的长度    if (fileLength != 0) {      response.reset();      response.setContentType("application/octet-stream;charset=utf-8"); // 改成输出excel文件      try {        response.setHeader(            "Content-disposition",            "attachment; filename="                + new String(fileName.getBytes("utf-8"),                    "ISO8859-1"));        response.setHeader("Content-Length", String.valueOf(fileLength));      } catch (UnsupportedEncodingException e) {        e.printStackTrace();      }      BufferedInputStream bis = null;      BufferedOutputStream bos = null;      FileInputStream fis = null;      try {        fis = new FileInputStream(downFilePath);        bis = new BufferedInputStream(fis);        // 输出流        bos = new BufferedOutputStream(response.getOutputStream());        byte[] buff = new byte[2048];        int bytesread;        // 写文件        while (-1 != (bytesread = bis.read(buff, 0, buff.length))) {          bos.write(buff, 0, bytesread);        }        // 跳转的路径        fis.close();        bis.close();        bos.close();      } catch (FileNotFoundException e) {        System.out.println("File is Not Exsist!");      }    } else {      // 抛异常      response.getWriter()          .write("<script charset='utf-8' type='text/javascript'>alert('该资源不存在！');history.go(-1);</script>");      return down;    }    down++;    return down;  }  /**   *   * @Description: 下载的模板   * @param @param response   * @param @param path 路径名   * @param @param name 模板名称   * @param @throws IOException   * @return void   * @throws   */  @SuppressWarnings("unused")  public static void downMb(HttpServletResponse response, String path,      String name) throws IOException {    Long fileLength = new File(path).length();// 文件的长度    System.out.println("文件的长度：" + fileLength);    if (fileLength != 0) {      response.reset();      response.setContentType("application/octet-stream;charset=utf-8"); // 改成输出excel文件      try {        response.setHeader(            "Content-disposition",            "attachment; filename="                + new String(name.getBytes("utf-8"),                    "ISO8859-1"));        response.setHeader("Content-Length", String.valueOf(fileLength));      } catch (UnsupportedEncodingException e) {        e.printStackTrace();      }      BufferedInputStream bis = null;      BufferedOutputStream bos = null;      FileInputStream fis = null;      try {        fis = new FileInputStream(path);        bis = new BufferedInputStream(fis);        // 输出流        bos = new BufferedOutputStream(response.getOutputStream());        byte[] buff = new byte[2048];        int bytesread;        // 写文件        while (-1 != (bytesread = bis.read(buff, 0, buff.length))) {          bos.write(buff, 0, bytesread);        }        fis.close();        bis.close();        bos.close();      } catch (FileNotFoundException e) {        System.out.println("File is Not Exsist!");      }    }  }}

//设置响应头，控制浏览器下载该文件，形参调的是文件的长度response.setHeader("Content-Length", String.valueOf(fileLength)); //设置响应类型，设置输出流类型response.setContentType("application/octet-stream;charset=utf-8"); // 改成输出excel文件

BufferedInputStream bis = null;BufferedOutputStream bos = null;

byte[] buff = new byte[2048];  int bytesread;  // 写文件  while (-1 != (bytesread = bis.read(buff, 0, buff.length))) {    bos.write(buff, 0, bytesread);  }

fis.close();bis.close();bos.close();