如何在Spring Boot中实现文件上传和下载

如何在Spring Boot中实现文件上传和下载

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引言

文件上传和下载是Web应用开发中常见的功能之一，Spring Boot通过其丰富的生态系统和简化的配置，使得实现这些功能变得非常简单。本文将详细介绍如何在Spring Boot中实现文件的上传和下载，并提供包含cn.juwatech.*包名的Java代码示例。

实现文件上传

1. 添加依赖

首先，需要在您的Spring Boot项目中添加文件上传的依赖。通常，您可以使用以下Maven配置：

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency><groupId>commons-fileupload</groupId><artifactId>commons-fileupload</artifactId><version>1.4</version>
</dependency>
<dependency><groupId>org.apache.commons</groupId><artifactId>commons-io</artifactId><version>1.3.2</version>
</dependency>

2. 配置文件上传接口

创建一个Controller来处理文件上传请求：

package cn.juwatech.controller;import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;
import java.io.File;
import java.io.IOException;@RestController
@RequestMapping("/file")
public class FileUploadController {@PostMapping("/upload")public String uploadFile(@RequestParam("file") MultipartFile file) {if (file.isEmpty()) {return "Please select a file to upload.";}try {byte[] bytes = file.getBytes();File destFile = new File("/path/to/upload/directory/" + file.getOriginalFilename());FileUtils.writeByteArrayToFile(destFile, bytes); // Ensure commons-io dependencyreturn "File uploaded successfully!";} catch (IOException e) {return "Failed to upload file: " + e.getMessage();}}
}

实现文件下载

1. 配置文件下载接口

创建一个Controller来处理文件下载请求：

package cn.juwatech.controller;import org.springframework.core.io.Resource;
import org.springframework.core.io.UrlResource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.nio.file.Path;
import java.nio.file.Paths;@RestController
@RequestMapping("/file")
public class FileDownloadController {@GetMapping("/download/{fileName:.+}")public ResponseEntity<Resource> downloadFile(@PathVariable String fileName) {Path filePath = Paths.get("/path/to/upload/directory/").resolve(fileName).normalize();Resource resource;try {resource = new UrlResource(filePath.toUri());if (resource.exists()) {return ResponseEntity.ok().header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + resource.getFilename() + "\"").body(resource);} else {return ResponseEntity.notFound().build();}} catch (MalformedURLException e) {return ResponseEntity.notFound().build();}}
}

示例代码：

以下是一个简单的示例代码，展示了如何在Spring Boot中实现文件的上传和下载：

package cn.juwatech.example;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
public class MyApp {public static void main(String[] args) {SpringApplication.run(MyApp.class, args);}
}