<div id="login-form">
        <!--<form id="uploadSongsForm" method="POST" action="/upload" enctype="multipart/form-data">-->
        <form id="uploadSongsForm"  enctype="multipart/form-data">

            <div  id="showMp3Files" class="tittle" >
                <div class
 
=" form-group">
                    <input type="file" name="file" id="mp3Files" >
                </div>
                <div class=" form-group">
                    <button type="reset" id="clearmp3" class="btn btn-dark">清除選擇歌曲</button>
                </div>
                <
 
div class=" form-group">
                    <input type="submit" value="上傳"  id="uploadBtn" class=" btn btn-primary" >
                </div>
            </div>
        </form>

jq程式碼

 $("#uploadSongsForm").submit(function () {
            $.post("/upload",{file:file},function
 
 (info) {
                if(info.flag){
                    alert(info.msg)
                }else{
                    //新增失敗
                    alert(info.msg);
                }
            });
            return false;

        });

controller程式碼

 private static final org.slf4j.Logger LOGGER = LoggerFactory.getLogger(FileUploadController.class);

    @GetMapping("/upload")
    public String upload() {
        return "upload";
    }

    @PostMapping("/upload")
    @ResponseBody
    public ResultInfo upload(@RequestParam("file") MultipartFile file) {
        ResultInfo info=new ResultInfo();
        info.setFlag(false);
        if (file.isEmpty()) {
            info.setMsg("檔案為空");
            info.setFlag(false);
            return info;
        }

        String fileName = file.getOriginalFilename();
        String filePath = "/mp3/";
        System.out.println("檔名:"+fileName);
        File dest = new File(filePath + fileName);
        try {
            file.transferTo(dest);
            LOGGER.info("succeed");
            info.setFlag(true);
            info.setMsg("上傳成功");
            return info;
        } catch (IOException e) {
            LOGGER.error(e.toString(), e);
        }
        info.setMsg("上傳失敗");
        return info;
    }

就我的猜測是jq段肯定是有錯誤的。

試著修改過來。

jq的ajax方法：

  $(window).ready(function () {
            $("#uploadBtn").click(function () {
                var formData=new FormData($("#uploadSongsForm")[0]);
                alert(formData);
                $.ajax({
                    url:"/upload",
                    type:"post",
                    data:formData,
                    cache:false,
                    processData: false,
                    contentType: false,
                    success:function (str) {
                        alert(str);
                    },
                    erro:
                    function (str) {
                        alert(str)
                    }


                    }
                )
            })
        })

這個好處就是，F12，請求的路徑都不顯示在瀏覽器裡。