文件模板导出案例

工具类：

package com.gl.manager.utils;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class DownloadUtil {
   
   private static final Logger LOG = LoggerFactory.getLogger(DownloadUtil.class);
   
   /**
    * @param filePath 要下载的文件路径
    * @param returnName 返回的文件名
    * @param response HttpServletResponse
    * @param delFlag 是否删除文件
    */
   protected void download(String filePath,String returnName,HttpServletResponse response,boolean delFlag){
      this.prototypeDownload(new File(filePath), returnName, response, delFlag);
   }

   /**
    * @param file 要下载的文件
    * @param returnName 返回的文件名
    * @param response HttpServletResponse
    * @param delFlag 是否删除文件
    */
   protected void download(File file,String returnName,HttpServletResponse response,boolean delFlag){
      this.prototypeDownload(file, returnName, response, delFlag);
   }
   
   /**
    * @param file 要下载的文件
    * @param returnName 返回的文件名
    * @param response HttpServletResponse
    * @param delFlag 是否删除文件
    */
   public void prototypeDownload(File file,String returnName,HttpServletResponse response,boolean delFlag){
      // 下载文件
      try(FileInputStream inputStream = new FileInputStream(file);ServletOutputStream outputStream = response.getOutputStream();) {
         if(!file.exists()) {
            return;
         }
         response.reset();
         //设置响应类型   PDF文件为"application/pdf"，WORD文件为："application/msword"， EXCEL文件为："application/vnd.ms-excel"。  
         response.setContentType("application/octet-stream;charset=utf-8");

         //设置响应的文件名称,并转换成中文编码
         //returnName = URLEncoder.encode(returnName,"UTF-8");
         returnName = response.encodeURL(new String(returnName.getBytes(),"iso8859-1"));    //保存的文件名,必须和页面编码一致,否则乱码
         
         //attachment作为附件下载；inline客户端机器有安装匹配程序，则直接打开；注意改变配置，清除缓存，否则可能不能看到效果
         response.addHeader("Content-Disposition",   "attachment;filename="+returnName);  
         
         int length = 1024;
         int readLength=0;
         byte buf[] = new byte[1024];
         readLength = inputStream.read(buf, 0, length);
         while (readLength != -1) {
            outputStream.write(buf, 0, readLength);
            readLength = inputStream.read(buf, 0, length);
         }
         outputStream.flush();
         //删除原文件
         if(delFlag) {           
            file.delete();
         }
      } catch (Exception e) {
         LOG.error(e.getMessage(), e);
      }
   }

   /**
    * @param byteArrayOutputStream 将文件内容写入ByteArrayOutputStream
    * @param response HttpServletResponse 写入response
    * @param returnName 返回的文件名
    */
   public void download(ByteArrayOutputStream byteArrayOutputStream, HttpServletResponse response, String returnName) throws IOException{
      response.setContentType("application/octet-stream;charset=utf-8");
      returnName = response.encodeURL(new String(returnName.getBytes(),"iso8859-1"));          //保存的文件名,必须和页面编码一致,否则乱码
      response.addHeader("Content-Disposition",   "attachment;filename=" + returnName);  
      response.setContentLength(byteArrayOutputStream.size());
      
      ServletOutputStream outputstream = response.getOutputStream(); //取得输出流
      byteArrayOutputStream.writeTo(outputstream);               //写到输出流
      byteArrayOutputStream.close();                         //关闭
      outputstream.flush();                                //刷数据
   }
}

实现类：

public void downloadFile() {
        try {
            // 读到流中
            InputStream in = this.getClass().getClassLoader().getResourceAsStream("static/供应商资料导入.xlsx");

            HttpServletResponse response = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getResponse();
            response.setHeader("Access-Control-Expose-Headers", "Content-Disposition");

            // 导出文件下载
            DownloadUtil downloadUtil = new DownloadUtil();
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            byte[] b = new byte[1024];
            int len;
            try {
                while ((len = in.read(b)) > 0) {
                    bos.write(b, 0, len);
                }

                in.close();
            } catch (IOException e) {
                log.error("Download the document is failed,message:{}", e.getMessage());
            }

            downloadUtil.download(bos, response, "template.xlsx");
        } catch (IOException e) {
            log.error(e.getMessage(), e);
        }
    }

简简单单