JavaWeb下载文件response

以下代码在 chrome、firefox，安卓自带手机浏览器上测试通过，但未经过完全测试，先记录下

    public static void downLoadFile(HttpServletRequest request,HttpServletResponse response,String fullPath,String fileName) throws IOException {
        OutputStream outp = response.getOutputStream();
        File file = new File(fullPath);
        if (file.exists()) {
            response.setContentType("APPLICATION/OCTET-STREAM");
　　　　　　  //response.setContentType("application/octet-stream; charset=utf-8");
            String filedisplay = fileName;
            String agent = (String)request.getHeader("USER-AGENT");  
            
            if(agent != null && ( agent.indexOf("MSIE") != -1 || agent.indexOf("Trident") != -1 || agent.indexOf("Mobile") != -1 )) {   
                //移动浏览器 或 ie  Trident是标识是ie浏览器 特别处理ie11 的问题
                filedisplay=URLEncoder.encode(filedisplay,"utf-8");
                System.out.println("下载文件，移动设备浏览器 或 ie[" + filedisplay + "]");  
                response.addHeader("Content-Disposition", "attachment;filename=" + filedisplay);
            } else {
　　　　　　　　  //其他浏览器
                String enableFileName = "=?UTF-8?B?" + (new String(Base64.getBase64(filedisplay))) + "?=";   
                System.out.println("下载文件，其他浏览器[" + enableFileName + "]");  
                response.setHeader("Content-Disposition", "attachment; filename=" + enableFileName);    
            }    
            
            FileInputStream in = null;
            try {
                outp = response.getOutputStream();
                in = new FileInputStream(fullPath);
                byte[] b = new byte[1024];
                int i = 0;
                while ((i = in.read(b)) > 0) {
                    outp.write(b, 0, i);
                }
                outp.flush();
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                if (in != null) {
                    in.close();
                    in = null;
                }
                if (outp != null) {
                    outp.close();
                    outp = null;
                    response.flushBuffer();
                }
            }
        } else {
            outp.write("文件不存在!".getBytes("utf-8"));
　　　　　　  outp.close();
        }
    }

    /**
     * 获取下载文件的content-type类型。
     * 
     * @param extName  文件后缀
     * @return
     */
    private String getContextType(String extName, boolean isRead) {
        String contentType = "application/octet-stream";
        if ("jpg".equalsIgnoreCase(extName) || "jpeg".equalsIgnoreCase(extName)) {
            contentType = "image/jpeg";
        } else if ("png".equalsIgnoreCase(extName)) {
            contentType = "image/png";
        } else if ("gif".equalsIgnoreCase(extName)) {
            contentType = "image/gif";
        } else if ("doc".equalsIgnoreCase(extName) || "docx".equalsIgnoreCase(extName)) {
            contentType = "application/msword";
        } else if ("xls".equalsIgnoreCase(extName) || "xlsx".equalsIgnoreCase(extName)) {
            contentType = "application/vnd.ms-excel";
        } else if ("ppt".equalsIgnoreCase(extName) || "pptx".equalsIgnoreCase(extName)) {
            contentType = "application/ms-powerpoint";
        } else if ("rtf".equalsIgnoreCase(extName)) {
            contentType = "application/rtf";
        } else if ("htm".equalsIgnoreCase(extName) || "html".equalsIgnoreCase(extName)) {
            contentType = "text/html";
        } else if ("swf".equalsIgnoreCase(extName)) {
            contentType = "application/x-shockwave-flash";
        } else if ("bmp".equalsIgnoreCase(extName)) {
            contentType = "image/bmp";
        } else if ("mp4".equalsIgnoreCase(extName)) {
            contentType = "video/mp4";
        } else if ("wmv".equalsIgnoreCase(extName)) {
            contentType = "video/x-ms-wmv";
        } else if ("wm".equalsIgnoreCase(extName)) {
            contentType = "video/x-ms-wm";
        } else if ("rv".equalsIgnoreCase(extName)) {
            contentType = "video/vnd.rn-realvideo";
        } else if ("mp3".equalsIgnoreCase(extName)) {
            contentType = "audio/mp3";
        } else if ("wma".equalsIgnoreCase(extName)) {
            contentType = "audio/x-ms-wma";
        } else if ("wav".equalsIgnoreCase(extName)) {
            contentType = "audio/wav";
        }
        if ("pdf".equalsIgnoreCase(extName) && isRead)// txt不下载文件，读取文件内容
        {
            contentType = "application/pdf";
        }
        if (("sql".equalsIgnoreCase(extName) || "txt".equalsIgnoreCase(extName)) && isRead)// pdf不下载文件，读取文件内容
        {
            contentType = "text/plain";
        }
        return contentType;
    }

其他参考，但未经验证

http 下载文件时,中文文件名在firefox下乱码的问题,一般在http header中是这样操作的:
"Content-Disposition","attachment;filename=文件名.xx"
其实,按照  rfc231 , Content-Disposition 应该按照如下格式设置:
"Content-Disposition","attachment;filename*=utf-8'zh_cn'文件名.xx"
只要严格按照标准设置以后,自然在各种浏览器下都会正常运行了.

String userAgent = request.getHeader("User-Agent");
    String rtn = "";
    try {
        String new_filename = URLEncoder.encode(fileName, "UTF8");
        // 如果没有UA，则默认使用IE的方式进行编码，因为毕竟IE还是占多数的
        rtn = "filename="" + new_filename + """;
        if (userAgent != null) {
            userAgent = userAgent.toLowerCase();
            // IE浏览器，只能采用URLEncoder编码
            if (userAgent.indexOf("msie") != -1) {
                rtn = "filename="" + new_filename + """;
            }
            // Opera浏览器只能采用filename*
            else if (userAgent.indexOf("opera") != -1) {
                rtn = "filename*=UTF-8''" + new_filename;
            }
            // Safari浏览器，只能采用ISO编码的中文输出
            else if (userAgent.indexOf("safari") != -1) {
                rtn = "filename="" + new String(fileName.getBytes("UTF-8"), "ISO8859-1") + """;
            }
            // Chrome浏览器，只能采用MimeUtility编码或ISO编码的中文输出
            else if (userAgent.indexOf("applewebkit") != -1) {
                new_filename = MimeUtility.encodeText(fileName, "UTF8", "B");
                rtn = "filename="" + new_filename + """;
            }
            // FireFox浏览器，可以使用MimeUtility或filename*或ISO编码的中文输出
            else if (userAgent.indexOf("mozilla") != -1) {
                rtn = "filename*=UTF-8''" + new_filename;
            }
        }
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
    return rtn;