读取ORACLE数据库中BOLB形式数据在前端预览

在controller层获取数据库中相应的BOLB数据，并转换成Inputstream

类似代码：

    @RequestMapping("/viewPDF.do")
    public void viewPDF(HttpServletRequest request, HttpServletResponse response, HttpSession session) {
        response.setContentType("application/pdf");
        FileInputStream in = null;
        OutputStream out = null;
        try {
            in = new FileInputStream(new File(request.getParameter("wid")));
            out = response.getOutputStream();
            byte[] b = new byte[512];
            while ((in.read(b)) != -1) {
                out.write(b);
            }
            out.flush();
            in.close();
            out.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

在前端js中添加响应事件

通过url直接访问controller中对应的方法，浏览器会根据具体输入流展示文件

var urL = contextPath + ' /sys/viewPDF?wid=/ '+wid;
window.open(url);