Retrieving blob from database using hibernate and displaying on web page using jsp

Question

Answer mentioned here This is not working for me I have sent bytes array to the database which is stored as a blob in the database

File file = new File(filePath);
byte[] imageData = new byte[(int) file.length()];

When I try to retrieve the blob object from the database in this byte array

I get a value like this "[B@526d24d9". I send this value to the jsp page.(I am sending a list of blobs to the jsp page i.e a list of bytes array) Now I am trying to render this image on a web page using jsp. But I am not able to figure out the most efficient approach one approach is to retrieve the list of blob ,process it and store it in a file and then retrieve from that filepath in the jsp page using the tag But I am looking for a more efficient approach. I am trying to something like this

jsp code

<c:forEach items="${list}" var="list" varStatus="loop">
   <c:set var="l" value="${loop.index}" />

    <tr>
    <td><c:out value= "${l+1}" /></td>
      <td><c:out value="${list.name}" /></td>
      <td><c:out value="${list.size} MB" /></td>
      <td><c:out value="${list.preview}" /></td>
      <td><i class="material-icons">edit</i>
      <i class="material-icons" onclick="Remove()">delete</i></td>
    </tr>
  </c:forEach>

list.preview contains the byte array "[B@526d24d9"

ca you share the code of how you are trying to display on jsp? — codeLover, Aug 30 '18 at 04:12
Please have a look at this solution https://stackoverflow.com/questions/10510416/convert-base64-byte-array-to-an-image — codeLover, Aug 30 '18 at 04:27

score 2 · Accepted Answer · answered Aug 30 '18 at 11:49

2

Create a String previewUrl field in your entity class. and inside the getter write this code .

public String getPreviewUrl() {
        String pu = Base64.encode(getPreview());
        setPreviewUrl(pu);
        return previewUrl;
    }

and in your jsp code ,

<td><img class='imagem_artigo' src='data:image/png;base64,${list.previewUrl}' alt='IMG DESC' width="200" height='200'></td>

This will work

answered Aug 30 '18 at 11:49

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Thankyou so much @HeenaMittal . This code is working and this is also a better approach. – iron_man Aug 30 '18 at 11:51

score 1 · Answer 2 · answered Aug 30 '18 at 07:41

keep in mind, that the data coming from your database is the actual bytes of the image file. What you need to put in your JSP is an tag with a reference to the picture. Additionally, you'll need a controller that just outputs the plain image as response - not embedded in HTML.

For Step 1, your JSP should look something like:

<tr>
  <td><c:out value= "${l+1}" /></td>
  <td><c:out value="${list.name}" /></td>
  <td><c:out value="${list.size} MB" /></td>
  <td><img src="<c:out value="${list.previewUrl}" />"></td>
  <td><i class="material-icons">edit</i>
  <i class="material-icons" onclick="Remove()">delete</i></td>
</tr>

(you'll need to define previewUrl and have it point to a controller that can write out the image data)

In the second step, you'd need to create such a controller that will output the contents of your image byte array to the output stream of the HttpServletResponse.

As a final note: I am a bit confused about the first snippet - are you retrieving the image data from a file or from database? (if the latter is the case, the size of the byte array might be calculated wrongly)

what code should I add in the controller class ? and this field previewurl where should I define this ? — iron_man, Aug 30 '18 at 07:55

Retrieving blob from database using hibernate and displaying on web page using jsp

2 Answers2