anxious! Problems reading pictures from a database and outputting them to a JSP page

aiveliu · Post time: 2020-3-9 13:30:02

...

try {

ResultSet rs = s.executeQuery ("select * from pictures");
response.setContentType ("image / jpeg");
OutputStream os = response.getOutputStream ();
out.write ("<table> <tr> <td> picture </ td> </ tr>");
while (rs.next ())
{

byte [] dt = rs.getBytes (2);
os.write (dt);

}
os.flush ();
rs.close ();

} catch (Exception e)
     {
         e.printStackTrace ();
         throw new SQLException ("Error:" + e);
     }
...
In SQL Server, there is a table named “pitures”, where the second field is of type “image”, there are three rows in the table, and the second field of each row is a .JPG image.
My question is: First, every time I read the data from the table using the above code and display it in the JSP page, only the picture in the first row is always displayed. No exception was thrown. Second, out.write () cannot output content to the JSP page.
Seeking a solution.

jccg03001200 · Post time: 2020-5-30 19:45:02

Follow the program

jccg03001200 · Post time: 2020-5-31 01:15:01

Put the TR in out.write ("<table> <tr> <td> picture </ td> </ tr>"); into the while loop to see

aiveliu · Post time: 2020-5-31 22:45:02

try {

ResultSet rs = s.executeQuery ("select * from pictures");
response.setContentType ("image / jpeg");
OutputStream os = response.getOutputStream ();
out.write ("Test picture output");
while (rs.next ())
{

byte [] dt = rs.getBytes (2);
os.write (dt);

}
os.flush ();
rs.close ();

} catch (Exception e)
     {
         e.printStackTrace ();
         throw new SQLException ("Error:" + e);
     }

The problem is still the same

bevande · Post time: 2020-6-2 09:00:02

Can multiple images be returned in one HTTP request?
Personally think it should be impossible, at least not so simple.
response.setContentType("image/jpeg");
This is a comment on a base64 encoded segment. How can a segment be mixed in a segment at the same time, as well as multiple images?

Therefore, multiple pictures should be given the access address in a page, which is accessed one by one by the browser and get separately
Your program can accept a parameter to determine which picture is being accessed to give a response.

okok02 · Post time: 2020-6-2 14:15:01

First read it out and store it in a temporary folder, then load the picture, isn't it better?

sundayday · Post time: 2020-6-5 09:00:01

It won't work like this.

Because you set the file header to be a picture type. Then it will display the entire returned content as the content of a picture 　
response.setContentType("image/jpeg");

This is a secondary response problem. .

You should first output the code of the entire page <html>.

Connect to the servlet where you want to display the picture
<html>
  <table>
<tr>
   <td>
      <img scr="Servlet connection..............." >
   </td>
   <td>
      <img scr="Servlet connection..............." >
   </td>
   <td>
      <img scr="Servlet connection..........." >
   </td>
</tr>
  </table>
<html>

bevande · Post time: 2020-6-25 01:30:01

sundaydaysaid what I meant

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