Struts实现文件下载

1.struts 1
通过struts实现文件下载有两种方式，一种是继承DownloadAction，一种是读取文件流然后output到response里面。
  1.继承DownloadAction，需要重写getStreamInfo方法，返回StreamInfo，DownloadAction有两个StreamInfo，FileStreamInfo和ResourceStreamInfo。
  例子:

protected StreamInfo getStreamInfo(ActionMapping actionMapping,
			ActionForm actionForm, HttpServletRequest servletRequest,
			HttpServletResponse servletResponse) throws Exception {
		servletResponse.setCharacterEncoding("UTF-8");
		String filename = java.net.URLEncoder.encode("filename", "UTF-8");
		servletResponse.setHeader("Content-Disposition", "inline; filename="
				+ new String(filename.getBytes("UTF-8"), "GBK"));
		File file = new File("test.jpg");
		StreamInfo si = new FileStreamInfo("image/jpeg"), file);

		return si;
	}
 

有关Content-Disposition的介绍可参见我的博客header Content-Disposition参数说明
例子中的编码部分是为了能够显示中文。

  2.重写resonse流

 

public ActionForward download(ActionMapping mapping, ActionForm form,    
            HttpServletRequest request, HttpServletResponse response) {    
        try   
        {    
            String path = new String(rootFolder +request.getParameter("path"));    
            File file = new File(path);    
            String filename = file.getName();    
                
            //取得文件的扩展名ext    
            String ext = filename.substring(filename.lastIndexOf(".") + 1).toUpperCase();    
                
            InputStream fis = new BufferedInputStream(new FileInputStream(path));    
            byte[] buffer = new byte[fis.available()];    
            fis.read(buffer);    
            fis.close();    
                
            response.reset();    
            response.addHeader("Content-Disposition", "attachment;filename="+new String(filename.getBytes()));    
            response.addHeader("Content-Length", ""+file.length()); //设置返回的文件类型    
            OutputStream toClient = new BufferedOutputStream(response.getOutputStream()); //得到向客户端输出二进制数据的对象    
            //根据扩展名声称客户端浏览器mime类型    
            if(ext.equals("DOC"))    
                response.setContentType("application/msword");    
            else   
                response.setContentType("application/octet-stream"); //设置返回的文件类型    
            toClient.write(buffer); //输出数据    
            toClient.flush();    
            toClient.close();    
            }    
            catch(IOException ex){    
                ex.printStackTrace();    
            }    
            return null;    
        }