java后台生成文件给前端下载（response输出流）

1、设置 ContentType

response.setContentType("application/x-download");

2、设置文件名，并指定编码格式

fileName = URLEncoder.encode("浏览器要显示的文件名", "UTF-8");
response.setCharacterEncoding("UTF-8");

3、将文件名 addHeader

response.addHeader("Content-Disposition", "attachment;filename=" + fileName);

4、读取文件流写入 response

File file = new File(filePath);
try {
       InputStream stream = new FileInputStream(file);

       ServletOutputStream out = response.getOutputStream();

       byte buff[] = new byte[1024];
       int length = 0;

       while ((length = stream.read(buff)) > 0) {
            out.write(buff,0,length);
       }
       stream.close();

       out.close();

       out.flush();

} catch (IOException e) {
       e.printStackTrace();
}

  controller 接口下载文件简单案例

@RestController
@RequestMapping("/test")
public class TestController {

    @GetMapping("/download")
    public void download(HttpServletResponse response) throws UnsupportedEncodingException {

        String filename = URLEncoder.encode("文件名.jpg", "UTF-8");

        response.setContentType("application/x-download");
        response.setHeader("Content-Disposition", "attachment;filename=" + filename);//浏览器上提示下载时默认的文件名

        try (ServletOutputStream out = response.getOutputStream();
             InputStream stream = new FileInputStream("D:\\最新测试.xls")){//读取服务器上的文件

            byte buff[] = new byte[1024];
            int length = 0;
            while ((length = stream.read(buff)) > 0) {
                out.write(buff,0,length);
            }
            stream.close();
            out.close();
            out.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}