java 将数据库中的blob字段转为图片显示在前端页面上

1.页面写法

  $("#zdytp").attr("src",ApiUrl+"/abc/getpic?orgid=8020");



2.后台写法（引入提示jar包即可）
 IOUtils 引入依赖

<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.4</version>
</dependency>
 @RequestMapping(value = "/imageDisplay")
 public  void imageDisplay(String orgid, HttpServletResponse response, HttpServletRequest request) throws IOException, SQLException {
          HashMap<String,Object> map = service.getById(orgid);//从数据库查询这条记录信息
     if (map != null && map.size() > 0) {
        byte[] bytes = (byte[]) map.get("orglogo");//orglogo为blob大字段 存储kb数据
        response.setContentType("image/jpeg, image/jpg, image/png, image/gif");  //设置输出流内容格式为图片格式
        InputStream in1 = new ByteArrayInputStream(bytes);  //将字节流转换为输入流
        IOUtils.copy(in1, response.getOutputStream());//将字节从 InputStream复制到OutputStream中
    }
    String logoRealPathDir = request.getSession().getServletContext()
            .getRealPath("/assets/images/icons.png");//获取默认图片路径
    response.setContentType("image/jpeg, image/jpg, image/png, image/gif");
    InputStream is = new FileInputStream(logoRealPathDir);

    IOUtils.copy(is, response.getOutputStream());
}


另一种写法

@RequestMapping(value = "/showImage.do")
public  void showImage(String id, HttpServletResponse response, HttpServletRequest request) throws IOException, SQLException {
    User user=userService.getUserById(Integer.valueOf(id));
    if(null != user){
        //从数据库读取出二进制数据……
        byte[] bb=user.getTp();
        // 将图像输出到Servlet输出流中。
        ServletOutputStream sos = response.getOutputStream();
        sos.write(bb, 0, bb.length);
        sos.close();
    }
    // 禁止图像缓存。
     response.setHeader("Pragma", "no-cache");
     response.setHeader("Cache-Control", "no-cache");
     response.setDateHeader("Expires", 0);
     response.setContentType("image/jpeg, image/jpg, image/png, image/gif");
}