在 Spring Boot 3 中，可以通过内置的文件处理机制结合 Java 的 IO 流与多线程技术，实现文件上传、多文件上传、大文件分片上传、文件流处理以及批量操作的需求。以下是详细实现步骤：
1. 单文件上传
控制器代码
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;@RestController
@RequestMapping("/file")
public class FileUploadController {private final String UPLOAD_DIR = "/path/to/upload/";@PostMapping("/upload")public ResponseEntity<String> uploadFile(@RequestParam("file") MultipartFile file) {try {File dest = new File(UPLOAD_DIR + file.getOriginalFilename());file.transferTo(dest); // 将上传的文件保存到目标位置return ResponseEntity.ok("File uploaded successfully: " + file.getOriginalFilename());} catch (IOException e) {e.printStackTrace();return ResponseEntity.internalServerError().body("File upload failed");}}
}
2. 多文件上传
控制器代码
@PostMapping("/upload-multiple")
public ResponseEntity<String> uploadMultipleFiles(@RequestParam("files") MultipartFile[] files) {StringBuilder message = new StringBuilder();for (MultipartFile file : files) {try {File dest = new File(UPLOAD_DIR + file.getOriginalFilename());file.transferTo(dest);message.append("Uploaded: ").append(file.getOriginalFilename()).append("\n");} catch (IOException e) {e.printStackTrace();return ResponseEntity.internalServerError().body("Failed to upload some files");}}return ResponseEntity.ok(message.toString());
}
3. 大文件分片上传
分片上传的核心在于将大文件拆分成小块上传，并在服务端进行合并。
分片上传控制器
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;import java.io.*;
import java.nio.file.Files;
import java.nio.file.Paths;@RestController
@RequestMapping("/file")
public class ChunkUploadController {private final String UPLOAD_DIR = "/path/to/upload/";@PostMapping("/upload-chunk")public ResponseEntity<String> uploadChunk(@RequestParam("file") MultipartFile file,@RequestParam("chunkNumber") int chunkNumber,@RequestParam("totalChunks") int totalChunks,@RequestParam("filename") String filename) {try {File chunkFile = new File(UPLOAD_DIR + filename + ".part" + chunkNumber);file.transferTo(chunkFile);// 如果所有分片都已上传完毕，则进行合并if (isAllChunksUploaded(filename, totalChunks)) {mergeChunks(filename, totalChunks);}return ResponseEntity.ok("Chunk " + chunkNumber + " uploaded successfully");} catch (IOException e) {e.printStackTrace();return ResponseEntity.internalServerError().body("Failed to upload chunk");}}private boolean isAllChunksUploaded(String filename, int totalChunks) {for (int i = 1; i <= totalChunks; i++) {if (!Files.exists(Paths.get(UPLOAD_DIR + filename + ".part" + i))) {return false;}}return true;}private void mergeChunks(String filename, int totalChunks) throws IOException {try (BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(UPLOAD_DIR + filename))) {for (int i = 1; i <= totalChunks; i++) {File chunkFile = new File(UPLOAD_DIR + filename + ".part" + i);Files.copy(chunkFile.toPath(), bos);chunkFile.delete(); // 合并后删除分片文件}}}
}
4. 文件流处理
文件流处理对于大文件来说可以减少内存占用，直接使用流式写入。
@PostMapping("/upload-stream")
public ResponseEntity<String> uploadFileStream(@RequestParam("file") MultipartFile file) {try (InputStream inputStream = file.getInputStream();OutputStream outputStream = new FileOutputStream(UPLOAD_DIR + file.getOriginalFilename())) {byte[] buffer = new byte[1024 * 1024]; // 1MB 缓冲区int bytesRead;while ((bytesRead = inputStream.read(buffer)) != -1) {outputStream.write(buffer, 0, bytesRead);}return ResponseEntity.ok("File uploaded successfully with streaming");} catch (IOException e) {e.printStackTrace();return ResponseEntity.internalServerError().body("File upload failed");}
}
5. 批量文件操作
示例：批量删除文件
@DeleteMapping("/delete-multiple")
public ResponseEntity<String> deleteMultipleFiles(@RequestParam List<String> filenames) {StringBuilder message = new StringBuilder();for (String filename : filenames) {File file = new File(UPLOAD_DIR + filename);if (file.exists() && file.delete()) {message.append("Deleted: ").append(filename).append("\n");} else {message.append("Failed to delete: ").append(filename).append("\n");}}return ResponseEntity.ok(message.toString());
}
6. 分片技术的前端配合
前端分片上传示例（React）
function uploadFileInChunks(file) {const chunkSize = 2 * 1024 * 1024; // 每片 2MBconst totalChunks = Math.ceil(file.size / chunkSize);let chunkNumber = 0;async function uploadChunk() {const start = chunkNumber * chunkSize;const end = Math.min(start + chunkSize, file.size);const chunk = file.slice(start, end);const formData = new FormData();formData.append("file", chunk);formData.append("chunkNumber", chunkNumber + 1);formData.append("totalChunks", totalChunks);formData.append("filename", file.name);await fetch("/file/upload-chunk", {method: "POST",body: formData,});chunkNumber++;if (chunkNumber < totalChunks) {uploadChunk();} else {console.log("Upload complete");}}uploadChunk();
}
总结
单文件上传：适用于小文件。
多文件上传：批量处理多个文件。
大文件分片上传：解决超大文件的上传需求，并支持断点续传。
文件流处理：高效处理大文件，降低内存占用。
批量操作：如批量删除、下载。
分片技术：结合前端分片，支持更高效的文件上传和管理。
可以根据具体业务需求选择合适的技术方案。