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();