关于Springboot+vue文件上传预览不了的问题

后台Controller

package com.example.kemanwu.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;

@RestController
public class AddzhangjieController {
    //对上传的文件做一个简单的分类,按照时间来
    SimpleDateFormat simpleDateFormat = new SimpleDateFormat("/yyyy/MM/dd/");

    @PostMapping("/upload")
    public Map<String, Object> fileUpload(MultipartFile file, HttpServletRequest req) {
        Map<String, Object> resultMap = new HashMap<>();

        // 得到上传时的文件名
        String originName = file.getOriginalFilename();
        if (!originName.endsWith(".pdf")) {
            resultMap.put("status", "error");
            resultMap.put("msg", "文件类型不对,必须为pdf");

            return resultMap;
        }

        String strFormat = simpleDateFormat.format(new Date());
        String realPath = req.getServletContext().getRealPath("/") + strFormat;
        String uploadDir = req.getSession().getServletContext().getRealPath("/") + "/upload/" + strFormat;

        File folder = new File(realPath);
        if (!folder.exists()) {
            folder.mkdirs();
        }

        // 保存文件对象,加上uuid是为了防止文件重名
        String strNewFileName = UUID.randomUUID().toString().replaceAll("-", "") + ".pdf";
        try {
            file.transferTo(new File(folder, strNewFileName));
            String strUrl = req.getScheme() + "://" + req.getServerName() + ":" + req.getServerPort() + strFormat + strNewFileName;
            resultMap.put("status", "success");
            resultMap.put("url", strUrl);
        } catch (IOException e) {
            e.printStackTrace();

            resultMap.put("status", "error");
            resultMap.put("msg", e.getMessage());
        }

        return resultMap;
    }

}

vue页面

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <!-- import CSS -->
    <link rel="stylesheet" href="https://unpkg.com/element-ui/lib/theme-chalk/index.css">
</head>
<body>
<div id="app">
    <el-upload
            action="/upload"
            :on-preview="handlePreview"
            multiple
            :limit="10"
            accept=".pdf">
        <el-button size="small" type="primary">点击上传</el-button>
        <div slot="tip" class="el-upload__tip">只能上传pdf文件,且不超过100MB</div>
    </el-upload>
</div>
</body>
<!-- import Vue before Element -->
<script src="https://unpkg.com/vue/dist/vue.js"></script>
<!-- import JavaScript -->
<script src="https://unpkg.com/element-ui/lib/index.js"></script>
<script>
    new Vue({
        el: '#app',
        methods: {
            handlePreview(file) {
                console.log(file);
                window.open( file.response.url);
            }
        }
    })
</script>
</html>

地址没有写错的地方就是显示404,postman返回的url浏览器也预览不出来显示404,找了好久没找到错啊哭了,我的项目路径是这样的也不会有问题

浏览器直接访问提交pdf?

对的直接访问

就按理来说地址输入就行就能看到预览,到我这不行

项目中没有添加静态文件映射,而且pdf好像不能直接在浏览器打开。