java 下载示例

package com.charmyin.cmstudio.common.utils;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import javax.servlet.http.HttpServletResponse;

public class DownLoadExcelUtil {

    
    public static void downLoadFile(String filePath, HttpServletResponse response, String fileName, String fileType)
            throws Exception {
            File file = new File(filePath);  //根据文件路径获得File文件
            //设置文件类型(这样设置就不止是下Excel文件了，一举多得)
            if("pdf".equals(fileType)){
               response.setContentType("application/pdf;charset=GBK");
            }else if("xls".equals(fileType)){
               response.setContentType("application/msexcel;charset=GBK");
            }else if("doc".equals(fileType)){
               response.setContentType("application/msword;charset=GBK");
            }
            //文件名
            response.setHeader("Content-Disposition", "attachment;filename=""
                + new String(fileName.getBytes(), "ISO8859-1") + """);
            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;
              //遍历，开始下载
              while ((n = input.read(buffer, 0, 4096)) > -1) {
                 output.write(buffer, 0, n);
              }
              output.flush();   //不可少
              response.flushBuffer();//不可少
            } catch (Exception e) {
              //异常自己捕捉       
            } finally {
               //关闭流，不可少
               if (input != null)
                    input.close();
               if (output != null)
                    output.close();
            }
        }
    
     public static HttpServletResponse download(String path, HttpServletResponse response) {
            try {
                // path是指欲下载的文件的路径。
                File file = new File(path);
                // 取得文件名。
                String filename = file.getName();
                // 取得文件的后缀名。
                String ext = filename.substring(filename.lastIndexOf(".") + 1).toUpperCase();

                // 以流的形式下载文件。
                InputStream fis = new BufferedInputStream(new FileInputStream(path));
                byte[] buffer = new byte[fis.available()];
                fis.read(buffer);
                fis.close();
                // 清空response
                response.reset();
                // 设置response的Header
                response.addHeader("Content-Disposition", "attachment;filename=" + new String(filename.getBytes()));
                response.addHeader("Content-Length", "" + file.length());
                OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
                response.setContentType("application/octet-stream");
                toClient.write(buffer);
                toClient.flush();
                toClient.close();
            } catch (IOException ex) {
                ex.printStackTrace();
            }
            return response;
        }
}