java如何将我刚刚生成的QRCode图像文件保存到服务器？

Question

public class QRCodeServlet extends HttpServlet {

    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        try {
            String qrtext = request.getParameter("qrtext");
            ByteArrayOutputStream out = QRCode.from(qrtext).to(ImageType.PNG).stream();

            response.setContentType("image/png");
            response.setContentLength(out.size());

            OutputStream outStream = response.getOutputStream();        
            outStream.write(out.toByteArray());
            outStream.flush();
            outStream.close();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>
}

下面是我用来生成QRCode的代码。我使用outputStream向浏览器显示QRCode。但我如何才能将QRCode保存为服务器上的图像文件，并使用标记将其显示在另一个html文件中呢？ 我使用iText库在这里生成QrCode

Answer 1

保存ByteArrayOutputStream图像的代码示例

String imageDir = //directory to save
String fileName = //file name
ByteArrayOutputStream out = //image byte arary
File file = new File(imageDir, fileName);
OutputStream outStream = new FileOutputStream(newFile);
outStream.write(out.toByteArray());
outStream.close();

Answer 2

如果保存是可选的，但HTML文件（实际上是JSP）中需要显示。。。下一个呢

如果请求中有参数txt：

<% var txt = request.getParameter("txt"); %>
<img src="/context/servletMapping?qrtext=<%=java.net.URLEncoder(txt, "UTF-8")%>">

关于JSTL，请参见How to URL-encode a String with JSTL?