# Struts2上傳檔案和下載檔案功能實作
[參考網站](https://www.itread01.com/content/1548975252.html)

<s:form id="mailMaintainAddform" method="post" enctype="multipart/form-data">
<tr>
    <th></font>附件上傳</th>
    <td colspan=3>
        <span style="font-weight: bold;">附加檔案1：</span>
        <s:file label="匯入" name="uploadFile" />
        <br>
        <span style="font-weight: bold;">附加檔案2：</span>
        <s:file label="匯入" name="uploadFile" />
        <br>
        <span style="font-weight: bold;">附加檔案3：</span>
        <s:file label="匯入" name="uploadFile" />
        <br>
    </td>
</tr>
</s:form>

private File [] uploadFile;
private String [] uploadFileFileName;
private String [] uploadFileContentType;
...getter setter

 if(uploadFile!=null){
    List<MailAttachment> attachmentlist = new ArrayList<MailAttachment>();
    for(int i=0;i<uploadFile.length;i++){
        //1.輸出上傳的型別
        logger.info("上傳的檔案:"+this.getUploadFile()[i]);
        logger.info("上傳檔案的名稱用File取得:"+this.getUploadFile()[i].getName());
        logger.info("直接用屬性取得名稱："+this.getUploadFileFileName()[i]);
        logger.info("檔案上傳的型別:"+this.getUploadFileContentType()[i]);
        String[] tempArray = this.getUploadFileFileName()[i].split("\\.");
        String fileType = "";
        if(tempArray.length > 0) {
            logger.info("tempArray[tempArray.length-1]:"+tempArray[tempArray.length-1]);
            fileType = tempArray[tempArray.length-1];
        }
        logger.info("FileType:"+fileType);

        logger.info("開始進行加密成BASE64");
        BASE64Encoder en = new BASE64Encoder();
        byte[] bytes = loadFile(this.getUploadFile()[i]);
        String encodedString = en.encodeBuffer(bytes);
        logger.info("加密BASE64完成");
        logger.info("encodedString:"+encodedString);

        MailAttachment att = new MailAttachment();
        att.setFileBase64(encodedString);
        att.setFileName(StringUtils.substring(this.getUploadFileFileName()[i],0,300));
        att.setFilePath("");
        att.setFileType(fileType);
        att.setMailAttSeq(mailDao.getSeqAttachmentNo());
        att.setMailSeq(seq);
        att.setCreateDate(DateUtils.getSysDate());
        att.setCreateTime(new Date());
        att.setCreateUserId(userId);
        attachmentlist.add(att);
    }
    logger.info("attachmentlist:"+attachmentlist);
    mailDao.saveMailAttachment(mailBean, attachmentlist);
}

 private static byte[] loadFile(File file) throws IOException {
    InputStream is = new FileInputStream(file);

    long length = file.length();
    if (length > Integer.MAX_VALUE) {
        // File is too large
    }
    byte[] bytes = new byte[(int)length];

    int offset = 0;
    int numRead = 0;
    while (offset < bytes.length
           && (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {
        offset += numRead;
    }

    if (offset < bytes.length) {
        throw new IOException("Could not completely read file "+file.getName());
    }

    is.close();
    return bytes;
}

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