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。
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。
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);
}
}
现在，您可以通过访问/download/{filename}端点来下载文件，其中{filename}是要下载的文件名。
这就是在Spring Boot中实现文件上传和下载的方法。请确保在application.properties或application.yml中设置正确的文件上传目录。例如，在application.properties中添加以下配置：
file.upload-dir=uploads/
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