該例基於Nutz框架

前臺代碼：

<a href="" id="errordownload"  onclick="downloadErrorLogsFile()"></a>

function downloadErrorLogsFile()
{$("errordownload").attr("href","${base}/platform/sys/user/downloaErrorLogsFile？filename="+filename);}

後臺Controler層：

/**
 * 下載模版或其他文件等，
 */
@At
@Ok("void")
public class
 
 Download {    
    //下載模版工具類
    public void downloadFile(@Param（fileName）String fileName，HttpServletRequest request,HttpServletResponse response) throws Exception {  

        response.setContentType("text/html;charset=UTF-8");

        BufferedInputStream in = null;  

        BufferedOutputStream out = null
 
;  
        request.setCharacterEncoding("UTF-8");  
        String rootpath = request.getSession().getServletContext().getRealPath("/");  
        try {  
            File f = new File(rootpath + "uploadFile/" + fileName);  
            response.setContentType("application/x-excel");  
            response.setCharacterEncoding(
 
"UTF-8");  
            response.setHeader("Content-Disposition", "attachment; filename="+new String(fileName.getBytes("gbk"),"iso-8859-1"));  
            response.setHeader("Content-Length",String.valueOf(f.length()));  
            in = new BufferedInputStream(new FileInputStream(f));  
            out = new BufferedOutputStream(response.getOutputStream());  
            byte[] data = new byte[1024];  
            int len = 0;  
            while (-1 != (len=in.read(data, 0, data.length))) {  
                out.write(data, 0, len);  
            }  
        } catch (Exception e) {  
            e.printStackTrace();  
        } finally {  
            if (in != null) {  
                in.close();  
            }  
            if (out != null) {  
                out.close();  
            }  
        }  
      
    }
}

POI之下載模板（或各種文件）