JSP实现点击链接后下载文件(相当于右键另存)功能

//**  
     * 实现文件另存功能  
     *   
     * @param text  
     *            文件内容  
     * @param fileName  
     *            文件名称  
     * @return  
     */  
    protected String renderFile(String text, String fileName)   
            throws IOException   
    {   
        response.addHeader("Content-Disposition", "attachment; filename="  
                + fileName);   
        response.setContentType("application/octet-stream");   
        response.setCharacterEncoding("GB2312");   
        response.getWriter().write(text);   
        response.flushBuffer();   
        response.getWriter().close();   
        return null;   
    }  



下载的action

/**  
     * 提供下载的方法  
     * @return  
     */  
    public String down()   
    {   
        String dir = getFullPath() + "/upload/file/";   
        try  
        {   
            if (!FileUtils.exists(dir))   
            {   
                new File(dir).mkdirs();   
            }   
            Random r = new Random(System.currentTimeMillis());   
            Integer randomInt = r.nextInt();   
            this.renderFile("test content:" + randomInt,randomInt + ".txt");   
        }   
        catch (IOException e)   
        {   
            e.printStackTrace();   
            this.renderText(e.getMessage());   
        }   
        return null;   
    }  


jsp页面链接调用:

<a href="${ctx}/va!down.do" >下载</a>