7.1、文件下载

使用ResponseEntity实现下载文件的功能

@RequestMapping("/testDown") 

public ResponseEntity<byte[]> testResponseEntity(HttpSession session) throws IOException { 
    //获取ServletContext对象 
    ServletContext servletContext = session.getServletContext();

    //获取服务器中文件的真实路径
    String realPath = servletContext.getRealPath("/static/img/1.jpg"); 

    //创建输入流 
    InputStream is = new FileInputStream(realPath);

    //创建字节数组 
    byte[] bytes = new byte[is.available()];

    //将流读到字节数组中 
    is.read(bytes); 

    //创建HttpHeaders对象设置响应头信息
    MultiValueMap<String, String> headers = new HttpHeaders(); 

    //设置要下载方式以及下载文件的名字 
    headers.add("Content-Disposition", "attachment;filename=1.jpg"); 

    //设置响应状态码 
    HttpStatus statusCode = HttpStatus.OK; 

    //创建ResponseEntity对象 
    ResponseEntity<byte[]> responseEntity = new ResponseEntity<>(bytes, headers, statusCode); 

    //关闭输入流 
    is.close();
    return responseEntity;
}