使用JAVA实现读取文件流并设置浏览器下载或直接预览

@RequestMapping(value = "getFile/{folder}/{fileName:.+}*", method = RequestMethod.GET)
 public void getFile(HttpServletResponse response, @PathVariable String folder,
      @PathVariable String fileName)
 {
  // 设置编码
  response.setCharacterEncoding("UTF-8");
  try
  {
 
   String path = folder + "/" + fileName;
   boolean flag = ossClient.doesObjectExist(ossProperties.getBucket(), path);
 
   // 判断文件是否存在
   if (flag)
   {
    // 清空response
    response.reset();
    // 设置response的Header，注意这句，如果开启，默认浏览器会进行下载操作，如果注释掉，浏览器会默认预览。
    // response.addHeader("Content-Disposition",
    // "attachment;filename=" + FileUtil.getOriginalFilename(path));
    // response.addHeader("Content-Length", "" + buf.length);
   
    OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
    // ByteArrayOutputStream bos = new ByteArrayOutputStream(1024);
    OSSObject ossObject = ossClient.getObject(ossProperties.getBucket(), path);
 
    String contentType = ossObject.getObjectMetadata().getContentType();
    System.out.println(contentType);
    //注意contentType类型
    response.setContentType(contentType);
 
    byte[] buf = new byte[1024];
    InputStream in = ossObject.getObjectContent();
 
    int L;
    while ((L = in.read(buf)) != -1)
    {
     // if (buf.length != 0)
     // {
     toClient.write(buf, 0, L);
     // }
    }
    in.close();
    // 写完以后关闭文件流
    toClient.flush();
    toClient.close();
    // response.getOutputStream().write(bos.toByteArray());
   }
   else
   {
    response.sendError(HttpServletResponse.SC_NOT_FOUND, "找不到相关资源");
   }
 
  }
  catch (IOException e)
  {
   e.printStackTrace();
  }
 }

package cn.hanquan.controller;
import java.io.File;
import java.io.IOException;

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

import org.apache.commons.io.FileUtils;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

@Controller
public class DemoDownload {
 @RequestMapping("download")
 public void download(String filename, HttpServletResponse res, HttpServletRequest req) throws IOException {
 // 设置响应流中文件进行下载
 // attachment是以附件的形式下载，inline是浏览器打开
 // bbb.txt是下载时显示的文件名
// res.setHeader("Content-Disposition", "attachment;filename=bbb.txt"); // 下载
 res.setHeader("Content-Disposition", "inline;filename=bbb.txt"); // 浏览器打开
 // 把二进制流放入到响应体中
 ServletOutputStream os = res.getOutputStream();
 System.out.println("here download");
 String path = req.getServletContext().getRealPath("files");
 System.out.println("path is: " + path);
 System.out.println("fileName is: " + filename);
 File file = new File(path, filename);
 byte[] bytes = FileUtils.readFileToByteArray(file);
 os.write(bytes);
 os.flush();
 os.close();
 }
}