spring boot中文件下载方法

 

使用HttpServletResponse，

1、转成StreamingResponseBody写入HttpServletResponse

@GetMapping("/downloadFile")
public void downloadFile(HttpServletResponse response) throws IOException {
    // 设置响应头，指定文件名
    response.setHeader("Content-Disposition", "attachment; filename=file.txt");

    // 获取文件输入流
    InputStream inputStream = new FileInputStream("path/to/file.txt");

    // 创建StreamingResponseBody对象，将文件内容写入响应输出流
    StreamingResponseBody responseBody = outputStream -> {
        byte[] buffer = new byte[1024];
        int bytesRead;
        while ((bytesRead = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, bytesRead);
        }
        inputStream.close();
    };

    // 返回StreamingResponseBody对象
    response.setContentType(MediaType.APPLICATION_OCTET_STREAM_VALUE);
    responseBody.writeTo(response.getOutputStream());
}

2、转成Bytes写入HttpServletResponse

@GetMapping("/downloadFiles")
public void downloadFile(HttpServletResponse response) throws IOException {

    byte[] data = Files.readAllBytes(Paths.get("D:\\file.txt"));
    // 设置响应头，指定文件名
    response.reset();
    response.setHeader("Content-Disposition", "attachment; filename=file.txt");
    response.addHeader("Content-Length", "" + data.length);
    response.setContentType(MediaType.APPLICATION_OCTET_STREAM_VALUE);
    response.getOutputStream().write(data);
}

　使用ResponseEntity类：

1、转成Bytes写入ResponseEntity

@GetMapping("/downloadFile")
public ResponseEntity<byte[]> downloadFile() throws IOException {
    // 读取文件内容到字节数组
    byte[] fileContent = Files.readAllBytes(Paths.get("path/to/file.txt"));

    // 设置响应头，指定文件名
    HttpHeaders headers = new HttpHeaders();
    headers.setContentDisposition(ContentDisposition.attachment().filename("file.txt").build());

    // 返回文件内容和响应头
    return ResponseEntity.ok().headers(headers).body(fileContent);
}

2、转成Resource写入ResponseEntity

@GetMapping("/downloadFile")
public ResponseEntity<Resource> downloadFile() {
    // 创建Resource对象，表示文件路径
    Resource fileResource = new FileSystemResource("path/to/file.txt");

    // 设置响应头，指定文件名
    HttpHeaders headers = new HttpHeaders();
    headers.setContentDisposition(ContentDisposition.attachment().filename("file.txt").build());

    // 返回文件资源和响应头
    return ResponseEntity.ok().headers(headers).body(fileResource);
}

3、转成InputStreamResource写入ResponseEntity

@GetMapping("/downloadFile")
public ResponseEntity<InputStreamResource> downloadFile() throws FileNotFoundException {
    // 创建文件输入流
    FileInputStream fileInputStream = new FileInputStream("path/to/file.txt");

    // 创建InputStreamResource对象，封装文件输入流
    InputStreamResource resource = new InputStreamResource(fileInputStream);

    // 设置响应头，指定文件名
    HttpHeaders headers = new HttpHeaders();
    headers.setContentDisposition(ContentDisposition.attachment().filename("file.txt").build());

    // 返回InputStreamResource对象和响应头
    return ResponseEntity.ok().headers(headers).body(resource);
}

　4、转成ByteArrayResource写入ResponseEntity

    @GetMapping("/downloadFiles")
    public ResponseEntity<ByteArrayResource> downloadFile() throws IOException {
        // 读取文件内容到字节数组
        byte[] fileContent = Files.readAllBytes(Paths.get("D:\\file.txt"));
        ByteArrayResource resource = new ByteArrayResource(fileContent);
        // 设置响应头，指定文件名
        HttpHeaders headers = new HttpHeaders();
        headers.setContentDisposition(ContentDisposition.attachment().filename("file9.txt").build());

        // 返回文件内容和响应头
        return new ResponseEntity<>(resource, headers, HttpStatus.OK);
    }