如何在servlet中处理上传的图像？

Question

In jsp page I have uploaded a image file and I forwarded that Jsp page to a Servlet and I want to retrieve that image in Servlet and add that image to Database ....... Can anyone explain how to retrieve image in servlet and add that image to database? Eg : We can retrieve string using request.getParameter("string"); In the same way is there any pre-defined method to retrive image? Eg: prepareStatement.setInt(colomnindex); In the same way is there any pre-defined method to add image to DataBase?

Answer 1

Something like this

HTML / JSP

< input type="file" name="foto" />

Serlvet

String fotoURL = req.getParameter("foto");
        System.out.println(fotoURL);
        URL urlFoto = null;
        urlFoto = getClass().getClassLoader().getResource(fotoURL); 


        System.out.println(urlFoto);
        BufferedImage foto = ImageIO.read(urlFoto);

Answer 2

Starting with, select a file for upload using JSP you need at least a HTML element which will display a file browse field.

<form action="upload" method="post" enctype="multipart/form-data">
   <input type="file" name="file">
   <input type="submit">
</form>

to retrieve the uploaded file inside servlet,

List<FileItem> items = new ServletFileUpload(new DiskFileItemFactory()).parseRequest(request);
for (FileItem item : items) {
   if (!item.isFormField()) {
    // <input type="file">
    System.out.println("Field name: " + item.getFieldName());
    System.out.println("File name: " + item.getName());
    System.out.println("File size: " + item.getSize());
    System.out.println("File type: " + item.getContentType());
  } else {
    // <input type="text|submit|hidden|password|button">, <select>, <textarea>,<button>
    System.out.println("Field name: " + item.getFieldName());
    System.out.println("Field value: " + item.getString());
  }              
 }

You just need to get the InputStream from the FileItem object and write it to any OutputStream.

   InputStream content = item.getInputStream();
                     OR
   item.write(new File("/uploads/filename.ext"));