SpringBoot 文件下载

第一步：创建SpringBoot项目 Maven依赖

    org.springframework.boot
    spring-boot-starter-web


    org.springframework.boot
    spring-boot-starter-thymeleaf


    com.fasterxml.jackson.core
    jackson-databind

application.yml

spring:
  #前缀，也就是模板存放的路径
  thymeleaf:
    prefix: classpath:/templates/
    #编码格式
    encoding: UTF-8
    #关闭缓存，不然无法看到实时页面
    cache: false
    #后缀
    suffix: .html
    #设置不严格的html
    mode: HTML
    servlet:
      content-type: text/html

在resources/static目录下添加一个名字为obj.jpg的图片。 第二步：编写前台页面：

    
        
        文件下载
    
    
        方式一：下载文件
        文件
        方式三：文件
    

第三步：编写后台Controller代码：

@Controller
public class FileDownloadController {
    @GetMapping("/download1")
    public ResponseEntity downloadFile(String fileName) throws IOException {
        String filePath = "E:/Demo/src/main/resources/static/" + fileName + ".jpg";
        FileSystemResource fsr = new FileSystemResource(filePath);
        HttpHeaders headers = new HttpHeaders();
        headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
        headers.add("Content-Disposition", String.format("attachment; filename=\"%s\"", fsr.getFilename()));
        headers.add("Pragma", "no-cache");
        headers.add("Expires", "0");
        return ResponseEntity
                .ok()
                .headers(headers)
                .contentLength(fsr.contentLength())
                .contentType(MediaType.parseMediaType("application/octet-stream"))
                .body(new InputStreamResource(fsr.getInputStream()));
    }

    @GetMapping(value = "/download2")
    public void getDownload(@RequestParam("fileName") String fileName, HttpServletRequest request, HttpServletResponse response) {
        String filePath = "E:/Demo/src/main/resources/static/" + fileName + ".jpg";
        File downloadFile = new File(filePath);

        ServletContext context = request.getServletContext();
        String mimeType = context.getMimeType(filePath);
        if (mimeType == null) {
            mimeType = "application/octet-stream";
            System.out.println("context getMimeType is null");
        }
        System.out.println("MIME type: " + mimeType);

        response.setContentType(mimeType);
        response.setContentLength((int) downloadFile.length());

        String headerKey = "Content-Disposition";
        String headerValue = String.format("attachment; filename=\"%s\"",
                downloadFile.getName());
        response.setHeader(headerKey, headerValue);

        try {
            InputStream myStream = new FileInputStream(filePath);
            IOUtils.copy(myStream, response.getOutputStream());
            response.flushBuffer();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //下载文件到用户桌面
    @ResponseBody
    @RequestMapping("/download3")
    public String downloadFile(String fileName, HttpServletResponse response) {
        if (fileName != null) {
            //设置文件路径
            String realPath = "E:/Demo/src/main/resources/";
            fileName = fileName + ".yml";
            File file = new File(realPath, fileName);
            if (file.exists()) {
                response.setContentType("application/octet-stream");//
                response.setHeader("content-type", "application/octet-stream");
                response.setHeader("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);
                    }
                    System.out.println("success");
                } 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 null;
    }
}