Question

我试图使用spring boot，我想创建一个上传文件的应用程序并返回它的哈希值。我已成功上传文件，但我不知道如何将其哈希值返回到新的html（或相同的html页面）。能否请你帮忙？这是我的代码：

@Controller
public class FileUploadController {

    @PostMapping("/")
    public String handleFileUpload(@RequestParam("file") MultipartFile file,
            RedirectAttributes redirectAttributes) throws NoSuchAlgorithmException, IOException {

        byte[] fileBytes = file.getBytes();
        MessageDigest sha256 = MessageDigest.getInstance("SHA-256");
        byte[] digest = sha256.digest(fileBytes);
        String hashString = new BigInteger(1, digest).toString(16);
        System.out.println("File hash: " + hashString);

        return "redirect:/test.html";
    }

和html：

<form method="POST" enctype="multipart/form-data" action="/">
  <table>
    <tr>
      <td>File to upload:</td>
      <td><input type="file" name="file" /></td>
    </tr>
    <tr>
      <td></td>
      <td><input type="submit" value="Upload" /></td>
    </tr>
  </table>
</form>

Answer 1

您已在代码中使用它了。使用Mouse

RedirectAttributes

然后从新页面的请求参数中获取该属性。

Answer 2

我已经做过研究，发现返回值的方法之一是使用百万美元资源，所以我的代码现在就像这样，它可以工作！包com.boot.test10.controller;

import java.io.IOException;
import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;

@Controller
public class ViewController {

    private String sha256String;

    @RequestMapping("/")
    public String Test(){
        return "index";
    }

    @RequestMapping("/hash")
    public String index(Model model){
        model.addAttribute("hash", sha256String);
        return "hash";
    }


    @PostMapping("/")
    public String handleFileUpload(@RequestParam("file") MultipartFile file,
            RedirectAttributes redirectAttributes) throws IOException, 
    `enter code here`NoSuchAlgorithmException {

        byte[] fileBytes = file.getBytes();
        MessageDigest sha256 = MessageDigest.getInstance("SHA-256");
        byte[] digest = sha256.digest(fileBytes);
        String sha256String = new BigInteger(1, digest).toString(16);
        this.sha256String = sha256String;

        return "redirect:/hash";
    }

    }

并且html是这样的：

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8" />
<title>Test Me</title>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css" integrity="sha384-/Y6pD6FV/Vv2HJnA6t+vslU6fwYXjCFtcEpHbNJ0lyAFsXTsjBbfaDjzALeQsN6M" crossorigin="anonymous" />
</head>
<body>
<p th:text="'The Hash Of The File Is: ' + ${hash}"></p>
</body>
</html>

如何在spring boot中将值返回给html

2 个答案: