SpringMVC下载图片，计算出图片的大小

女爷i 2023-10-11 15:08 28阅读 0赞

@GetMapping("/pic")
        public void pic(HttpServletResponse response) throws IOException {
        
            int total = 0;
            response.setContentType("image/jpeg");//设置输出流内容格式为图片格式
            response.setCharacterEncoding("utf-8");//response的响应的编码方式为utf-8
            ServletOutputStream os = response.getOutputStream();
            //读取图片
            FileInputStream inputStream = new FileInputStream("01.jpg");
            byte[] bytes = new byte[1024];
            while (true){
        
                int len = inputStream.read(bytes);
                if (len == -1){
        
                    break;
                }
                total = total + len;
                //获取字节数组中的数据
                os.write(bytes,0,len);
            }
    
            System.out.println("图片大小为" + (total / 1024) + "kb");
        }

这里使用的字节数组为10240个字节。  
启动应用  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNzUwNjU2_size_16_color_FFFFFF_t_70]

后台打印输出  
![在这里插入图片描述][20201217130435371.png]  
看看图片的大小，这里丢失了一定精度  
![在这里插入图片描述][20201217130508831.png]使用BigDecimal再次计算

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNzUwNjU2_size_16_color_FFFFFF_t_70 1]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNzUwNjU2_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20201217130416806.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNzUwNjU2,size_16,color_FFFFFF,t_70
[20201217130435371.png]: https://img-blog.csdnimg.cn/20201217130435371.png
[20201217130508831.png]: https://img-blog.csdnimg.cn/20201217130508831.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNzUwNjU2_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20201217130825955.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNzUwNjU2,size_16,color_FFFFFF,t_70