Spring Boot实现文件上传下载

蜗牛互联网技术资讯 2024-10-05 6 0

在Spring Boot中，实现文件上传和下载非常简单。我们将分别介绍如何使用Spring Boot处理文件上传和文件下载。

文件上传

首先，我们需要在pom.xml文件中添加以下依赖：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

接下来，创建一个简单的HTML表单，用于文件上传：

<!DOCTYPE html>
<html>
<head>
    <title>File Upload</title>
</head>
<body>
    <h1>Upload a file</h1>
    <form action="/upload" method="post" enctype="multipart/form-data">
        <input type="file" name="file" />
        <button type="submit">Upload</button>
    </form>
</body>
</html>

现在，我们将在Controller中处理文件上传请求：

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

@RestController
public class FileUploadController {

    private static final String UPLOAD_DIR = "uploads/";

    @PostMapping("/upload")
    public ResponseEntity<String> uploadFile(@RequestParam("file") MultipartFile file) {
        if (file.isEmpty()) {
            return new ResponseEntity<>("Please select a file to upload.", HttpStatus.BAD_REQUEST);
        }

        try {
            byte[] bytes = file.getBytes();
            Path path = Paths.get(UPLOAD_DIR + file.getOriginalFilename());
            Files.write(path, bytes);

            return new ResponseEntity<>("File uploaded successfully: " + file.getOriginalFilename(), HttpStatus.OK);
        } catch (IOException e) {
            e.printStackTrace();
            return new ResponseEntity<>("Failed to upload file: " + file.getOriginalFilename(), HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }
}

这将创建一个名为"uploads"的文件夹，用于存储上传的文件。

文件下载

为了实现文件下载，我们将在Controller中添加一个新的方法：

import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

@RestController
public class FileDownloadController {

    private static final String UPLOAD_DIR = "uploads/";

    @GetMapping("/download/{filename}")
    public ResponseEntity<Resource> downloadFile(@PathVariable String filename) {
        Path path = Paths.get(UPLOAD_DIR + filename);
        Resource resource = null;

        try {
            byte[] bytes = Files.readAllBytes(path);
            resource = new ByteArrayResource(bytes);
        } catch (IOException e) {
            e.printStackTrace();
            return new ResponseEntity<>(HttpStatus.NOT_FOUND);
        }

        return ResponseEntity.ok()
                .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + resource.getFilename() + "\"")
                .body(resource);
    }
}