以下是用 Spring Boot 3 构建的文件上传和读取接口示例代码：

项目依赖

确保在 pom.xml 文件中添加了以下依赖：

       

        
xml
        
        

         

          

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

        
       

文件目录结构

我们将文件上传到本地文件夹，例如 uploads/，然后通过文件名读取。

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主代码实现

1. 配置类

配置上传文件的存储路径。

       

        
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         package com.example.fileupload.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.beans.factory.annotation.Value;

@Configuration
public class FileUploadConfig {

    @Value("${file.upload-dir:uploads/}")
    private String uploadDir;

    public String getUploadDir() {
        return uploadDir;
    }
}

        
       

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2. 控制器

实现上传和读取文件的 REST API。

       

        
java
        
        

         

          

           
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         package com.example.fileupload.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpHeaders;
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.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

import com.example.fileupload.config.FileUploadConfig;

@RestController
@RequestMapping("/api/files")
public class FileController {

    private final String uploadDir;

    @Autowired
    public FileController(FileUploadConfig fileUploadConfig) {
        this.uploadDir = fileUploadConfig.getUploadDir();
        File dir = new File(uploadDir);
        if (!dir.exists()) {
            dir.mkdirs(); // 创建上传目录
        }
    }

    // 上传文件接口
    @PostMapping("/upload")
    public ResponseEntity<String> uploadFile(@RequestParam("file") MultipartFile file) {
        if (file.isEmpty()) {
            return ResponseEntity.status(HttpStatus.BAD_REQUEST).body("File is empty");
        }

        try {
            // 保存文件到指定路径
            String fileName = file.getOriginalFilename();
            Path filePath = Paths.get(uploadDir, fileName);
            Files.write(filePath, file.getBytes());
            return ResponseEntity.ok("File uploaded successfully: " + fileName);
        } catch (IOException e) {
            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
                                 .body("File upload failed: " + e.getMessage());
        }
    }

    // 获取文件接口
    @GetMapping("/{fileName}")
    public ResponseEntity<byte[]> getFile(@PathVariable String fileName) {
        try {
            Path filePath = Paths.get(uploadDir, fileName);
            byte[] fileContent = Files.readAllBytes(filePath);

            // 设置文件响应头
            HttpHeaders headers = new HttpHeaders();
            headers.add(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + fileName + "\"");
            headers.add(HttpHeaders.CONTENT_TYPE, Files.probeContentType(filePath));

            return ResponseEntity.ok()
                                 .headers(headers)
                                 .body(fileContent);
        } catch (IOException e) {
            return ResponseEntity.status(HttpStatus.NOT_FOUND).body(null);
        }
    }
}

        
       

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3. 应用主类

创建 Spring Boot 的主类。

       

        
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         package com.example.fileupload;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class FileUploadApplication {
    public static void main(String[] args) {
        SpringApplication.run(FileUploadApplication.class, args);
    }
}

        
       

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测试接口

上传文件

请求:
POST /api/files/upload
参数: form-data 中 key 为 file，值为文件。

获取文件

请求:
GET /api/files/{fileName}
将文件名作为路径参数。

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示例运行

1. 启动项目后，访问上传接口上传文件：

            
   
             
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              curl -F "file=@example.txt" http://localhost:8080/api/files/upload
   
             
            

2. 获取文件内容：

            
   
             
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              curl -O http://localhost:8080/api/files/example.txt