SpringBoot文件上传下载

SpringBoot单个文件上传、批量文件上传、文件下载样例：

package demo.crotroller;

import java.io.BufferedInputStream;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;

import lombok.extern.slf4j.Slf4j;

/**
 *	文件上传下载demo
 */
@RestController
@Slf4j
public class FileUploadDemo {

	// 单个文件上传
	@PostMapping(value = "/upload")
	public String upload(@RequestParam("file") MultipartFile file) {
		try {
			if (file.isEmpty()) {
				return "文件为空";
			}
			// 获取文件名
			String fileName = file.getOriginalFilename();
			log.info("上传的文件名为：" + fileName);
			// 获取文件的后缀名
			String suffixName = fileName.substring(fileName.lastIndexOf("."));
			log.info("文件的后缀名为：" + suffixName);
			// 设置文件存储路径
			String filePath = "D:/Test/Downloads/";
			String path = filePath + fileName;
			File dest = new File(path);
			// 检测是否存在目录
			if (!dest.getParentFile().exists()) {
				dest.getParentFile().mkdirs();// 新建文件夹
			}
			file.transferTo(dest);// 文件写入
			return "上传成功";
		} catch (IllegalStateException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return "上传失败";
	}

	// 文件批量上传
	@PostMapping("/batchupload")
	public String handleFileUpload(HttpServletRequest request) {
		List files = ((MultipartHttpServletRequest) request).getFiles("file");
		MultipartFile file = null;
		BufferedOutputStream stream = null;
		for (int i = 0; i < files.size(); ++i) {
			file = files.get(i);
			// 获取文件名
			String fileName = file.getOriginalFilename();
			String filePath = "D:/Test/Downloads/";
			String path = filePath + fileName;
			File dest = new File(path);
			// 检测是否存在目录
			if (!dest.getParentFile().exists()) {
				dest.getParentFile().mkdirs();// 新建文件夹
			}
			if (!file.isEmpty()) {
				try {
					byte[] bytes = file.getBytes();
					stream = new BufferedOutputStream(
							new FileOutputStream(new File(filePath + file.getOriginalFilename())));// 设置文件路径及名字
					stream.write(bytes);// 写入
					stream.close();
				} catch (Exception e) {
					stream = null;
					return "第 " + i + " 个文件上传失败 ==> " + e.getMessage();
				}
			} else {
				return "第 " + i + " 个文件上传失败因为文件为空";
			}
		}
		return "上传成功";
	}

	// 文件下载
	@GetMapping("/downloadfile")
	public String downloadFile(HttpServletRequest request, HttpServletResponse response) {
		String fileName = "1111.txt";// 文件名
		if (fileName != null) {
			// 设置文件路径
			File file = new File("D:/Test/Downloads/1111.txt");
			// File file = new File(realPath , fileName);
			if (file.exists()) {
				response.setContentType("application/force-download");// 设置强制下载不打开
				response.addHeader("Content-Disposition", "attachment;fileName=" + fileName);// 设置文件名
				byte[] buffer = new byte[1024];
				FileInputStream fis = null;
				BufferedInputStream bis = null;
				try {
					fis = new FileInputStream(file);
					bis = new BufferedInputStream(fis);
					OutputStream os = response.getOutputStream();
					int i = bis.read(buffer);
					while (i != -1) {
						os.write(buffer, 0, i);
						i = bis.read(buffer);
					}
					log.info("下载"+fileName+"成功");
					return "下载成功";
				} catch (Exception e) {
					e.printStackTrace();
				} finally {
					if (bis != null) {
						try {
							bis.close();
						} catch (IOException e) {
							e.printStackTrace();
						}
					}
					if (fis != null) {
						try {
							fis.close();
						} catch (IOException e) {
							e.printStackTrace();
						}
					}
				}
			}
		}
		return "下载失败";
	}

}

在application.yml中配置文件上传的大小：

spring:
    servlet:
        multipart:
            # 单个文件的最大值
            max-file-size: 10MB
            # 上传文件总的最大值
            max-request-size: 10MB

postman测试单个文件上传：

测试多文件上传：

浏览器输入http://localhost:9000/downloadFile测试下载文件成功。