下载文件

// 防止IE缓存
        response.setHeader("pragma", "no-cache");
        response.setHeader("cache-control", "no-cache");
        response.setDateHeader("Expires", 0);
        // 设置编码
        response.setCharacterEncoding("UTF-8");
        response.reset();
        // 解决在弹出文件下载框不能打开文件的问题
        response.setContentType("application/octet-stream;charset=" + "GBK");
       response.setContentType("application/x-msdownload");

//防止中文乱码或不能获取中文文件名
String fileNameEncode = new String(fileName.getBytes("GBK"), "ISO8859-1");

String headValue = "attachment;filename=" + fileNameEncode; 
        response.addHeader("Content-Disposition",headValue);