Java中HTTP下载文件——并解决跨域

1、常用的需要设置的MIME类型

任何文件（二进制文件）    application/octet-stream

.doc      application/msword
.dot      application/msword
 
.docx     application/vnd.openxmlformats-officedocument.wordprocessingml.document
.dotx     application/vnd.openxmlformats-officedocument.wordprocessingml.template
.docm     application/vnd.ms-word.document.macroEnabled.12
.dotm     application/vnd.ms-word.template.macroEnabled.12
 
.xls      application/vnd.ms-excel
.xlt      application/vnd.ms-excel
.xla      application/vnd.ms-excel
 
.xlsx     application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
.xltx     application/vnd.openxmlformats-officedocument.spreadsheetml.template
.xlsm     application/vnd.ms-excel.sheet.macroEnabled.12
.xltm     application/vnd.ms-excel.template.macroEnabled.12
.xlam     application/vnd.ms-excel.addin.macroEnabled.12
.xlsb     application/vnd.ms-excel.sheet.binary.macroEnabled.12
 
.ppt      application/vnd.ms-powerpoint
.pot      application/vnd.ms-powerpoint
.pps      application/vnd.ms-powerpoint
.ppa      application/vnd.ms-powerpoint
 
.pptx     application/vnd.openxmlformats-officedocument.presentationml.presentation
.potx     application/vnd.openxmlformats-officedocument.presentationml.template
.ppsx     application/vnd.openxmlformats-officedocument.presentationml.slideshow
.ppam     application/vnd.ms-powerpoint.addin.macroEnabled.12
.pptm     application/vnd.ms-powerpoint.presentation.macroEnabled.12
.potm     application/vnd.ms-powerpoint.template.macroEnabled.12
.ppsm     application/vnd.ms-powerpoint.slideshow.macroEnabled.12
 
.mdb      application/vnd.ms-access

.zip      application/zip
.tar      application/x-tar

//图片
.png      image/png
.jpg      image/jpeg

2、下载代码

2.1、工具类

encodeFileName方法

2.2、下载

• 解决跨域不显示在header里面的问题
• encodeFileName方法见：ExportWordDemo --> com.cc.ewd.download.DownloadUtils#encodeFileName

    /** 标准下载的方法
     * @param response HttpServletResponse
     * @since 2023/5/18 0018
     * @author CC
     **/
    public void standardDownload(HttpServletRequest request, HttpServletResponse response){
        try {
            //构建好的需要下载的bytes数组
            byte[] bytes = new byte[1];
            String fileName = "文件名.doc";

            response.setCharacterEncoding(StandardCharsets.UTF_8.name());
            response.setContentType("image/png;charset=".concat(StandardCharsets.UTF_8.name()));
            //Access-Control-Expose-Headers ：解决跨域不显示在header里面的问题
           response.setHeader(HttpHeaders.ACCESS_CONTROL_EXPOSE_HEADERS,HttpHeaders.CONTENT_DISPOSITION);
            response.setHeader(HttpHeaders.CONTENT_DISPOSITION,
                    "attachment; filename=".concat(
                            URLEncoder.encode(fileName, StandardCharsets.UTF_8.name())
                    ));
            ServletOutputStream out = response.getOutputStream();

            out.write(bytes);
            out.flush();
            out.close();
        }catch(Exception e){
            e.printStackTrace();
        }
    }