11、注解篇@ResponseBody@RequestBody

@RequestMapping("/testResponseEntity")
    public ResponseEntity<byte[]> testResponseEntity(HttpSession session) throws IOException{
        byte [] body = null;
        ServletContext servletContext = session.getServletContext();
        InputStream in = servletContext.getResourceAsStream("/files/abc.txt");
        body = new byte[in.available()];
        in.read(body);
        
        HttpHeaders headers = new HttpHeaders();
        headers.add("Content-Disposition", "attachment;filename=abc.txt");
        
        HttpStatus statusCode = HttpStatus.OK;
        
        ResponseEntity<byte[]> response = new ResponseEntity<byte[]>(body, headers, statusCode);
        return response;
    }
    
    @ResponseBody
    @RequestMapping("/testHttpMessageConverter")
    public String testHttpMessageConverter(@RequestBody String body){
        System.out.println(body);
        return "helloworld! " + new Date();
    }

spring mvc请求和相应都会使用到HttpMessageConverter进行处理对象
对应注解为@ResponseBody和@RequestBody
注解又对应两个对象HttpEntity<T> / ResponseEntity<T>