java使用io流下载.docx. xlsx文件，出现文件损坏提示

介绍
在使用io流下载服务器上的资源文件时，出现以下提示：但是选择“是”后文件可以正常打开
 


 

 
参考
[codesyntax lang="java"]
@RequestMapping(value = "downLoadInstruction")
public void downLoadInstruction(HttpServletRequest request,HttpServletResponse response) {
   BufferedOutputStream out = null;
   InputStream is = null;
   try {
       response.reset();
       response.setCharacterEncoding("UTF-8");
       String filename = "专家信息管理系统使用说明.docx";
       response.setContentType("application/msword");
       String templatePath = request.getSession().getServletContext().getRealPath("/template/instructionsForUse.docx");
        //下载是否使用的火狐浏览器
        String agent = request.getHeader("User-Agent");
        boolean isMSIE = (agent != null && agent.indexOf("MSIE") != -1);
        if(isMSIE){
             response.setHeader("Content-Disposition", "attachment;filename="+URLEncoder.encode(filename, "UTF-8"));
         }else{
             response.setHeader("Content-Disposition", "attachment;filename="+ new String(filename.getBytes("UTF-8"), "ISO-8859-1"));    
            }
            
          out = new BufferedOutputStream(response.getOutputStream());
          is = new BufferedInputStream(new FileInputStream(new File(templatePath)));
          byte[] content = new byte[1024];
          int len = 0;
          while ((len = is.read(content)) > 0) {
             out.write(content, 0, len);
          }  
                //注释1
                //out.write(content);
          out.flush();
     } catch (Exception e) {
         e.printStackTrace();
     }finally{
         try {
             if(is!=null){
                 is.close();
              }
              if(out!=null){
                  out.close();
              }
          } catch (Exception e2) {
              e2.printStackTrace();
          }
    } 
 }
[/codesyntax]

代码中需要将注释1的地方注释掉，不然就会出现文件损坏，原因在于“尝试每次读取1024个字节，写入buffer数组，如果少于1024，就会返回实际读取的字节，os.write(buffer);可能多了“。