# Struts2 附件檔案下載功能
[前情提要](https://hackmd.io/1XW2--RGSgmDxelLUtXUBQ)

<s:hidden id="fileName" name="fileName" />
<s:hidden id="mailAttSeq" name="mailAttSeq" />
<tr>
    <th>附件</th>
    <td>
        <s:iterator value="%{mailMaintainDetailVo.mailAttachmentList}">
            <s:property value="fileName"/>
            <input name="btnEnter" type="button" class="btnHL" value="下載" onclick="mailAttachmentDownload('<s:property value="fileName"/>','<s:property value="mailAttSeq"/>')" />
            <br>
        </s:iterator>
    </td>
</tr>

function mailAttachmentDownload(fileName,mailAttSeq) {
    jQuery("#fileName").val(fileName);
    jQuery("#mailAttSeq").val(mailAttSeq);
    jQuery("#mailMaintainDetailform").attr('action', 'mailAttachmentDownload').submit();
}

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

private InputStream stream;
private String fileName;
private String mailAttSeq;
...getter setter

@Action(value = "mailAttachmentDownload", results = {@Result(name ="success", type = "stream", params = {"contentType",
            "application/octet-stream","inputName", "stream", "contentDisposition",
            "attachment;filename=\"${fileName}\"", "bufferSize", "1024"}),
            @Result(name = DETAIL, location = "sysMaintain.mailMaintainDetail.tiles", type = "tiles")})
@SkipValidation
public String mailAttachmentDownload() {
    logger.info("mailAttachmentDownload");
    logger.info("fileName:"+fileName);
    logger.info("mailAttSeq:"+mailAttSeq);
    try {
        HttpServletRequest request = getHttpServletRequest();
        String userAgent = request.getHeader("User-Agent");

        BASE64Decoder de = new BASE64Decoder();
        byte[] resultByte = null;
        if (StringUtils.isNotBlank(mailAttSeq)) {
            MailAttachment mailAttachment = mailDao.getMailAttachment(mailAttSeq);
            logger.info("mailAttachment: "+mailAttachment);
            if(mailAttachment != null) {
                resultByte = de.decodeBuffer(mailAttachment.getFileBase64());
                stream = new ByteArrayInputStream(resultByte);
            }
        }

        if(userAgent.contains("IE")){ //中文檔名給予
            fileName = java.net.URLEncoder.encode(fileName,"UTF-8");

        }else{
            fileName= new String(fileName.getBytes("UTF-8"),"ISO-8859-1");
        }

        return SUCCESS;
    } catch (Exception e) {
        e.printStackTrace();
        //response.setHeader("Set-Cookie", "fileDownload=true; path=/");
        logger.error("下載失敗 ERROR IS " + e);
        message = " 下載失敗 , 發生錯誤 !" ;

        return DETAIL;
    }
}

###### tags: `javascript` `Java`