我想将数据库中的多个图像显示到jsp中（我正在映射servlet），所以在jsp中，它将显示在img标签的src中

Question

I am using longblob data type in a table to store image,At least, five images are stored, I want to retrieve all images from the database and want to display on jsp which consists of image tag, an image tag's attribute src is assigned to the servlet name as src="./Serv1", this Serv1 contains image retrieved from database but the problem is I have no idea how to show multiple images, It is showing only the first image, should I use loop if yes then how?

I have this in JSP page

 while(r.next())

              {

      %>
      <img src="./Serv1" height="100" width="200"> 
      <p>Product <%=r.getInt(1)%>: <%=r.getString(2)%></p>

and my servlet whose url-pattern is Serv1 has this code

   ResultSet r=st.executeQuery("select prodimg from product;");

if(r.next()){

                img= r.getBlob(1);

              imgbyte=img.getBytes(1, (int)img.length());
              response.setContentType("image/jpg");
              oos=response.getOutputStream();

           }

            oos.write(imgbyte);
            con.close();

Answer 1

Suppose you have jsp page where you want to retrieve image. You can do something like this to retrieve any image from database.

 <% // dbconnection
          try {
                   Class.forName("com.mysql.jdbc.Driver");
                 java.sql.Connection conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/project","root","");
                  Statement statement = conn.createStatement() ;
       resultSet=statement.executeQuery("select * from product") ; 
                %> 
    <!--this loop will get all images-->
       <% while(resultSet.next()){ %> 
    <!--I'm using id column of table,you can use any coulmn which is unique to all row-->
   Image - <img src="./Serv1?id=<%=resultSet.getString("id")%>" width="20%"/>
  < p>Product <%=r.getInt(1)%>: <%=r.getString(2)%></p>

    <% 
    }
    }catch(Exception e){}

    %>

In Above code this -> <img src="./Serv1?id=<%=resultSet.getString("id")%>" /> line is important ,here you are passing parameter ie : id to servlet to get particular image

Now,in your servlet ie ./Serv1 you have to retrieve the id in doGet and pass in query ,lastly send back the reponse to jsp page .

Blob image = null;
        byte[] imgData = null;
       String id= request.getParameter("id");//here you are getting id 
       int i;
       ResultSet rs =null;

 try {

            //loading drivers for mysql
           Class.forName("com.mysql.jdbc.Driver");
             Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/project","root","");


         String sql = "SELECT prodimg FROM product where id=?"; //here pass that id in query to get particular image 

           PreparedStatement ps = con.prepareStatement(sql);


               ps.setString(1, id);
              rs = ps.executeQuery();    
 while (rs.next()) {
                  image = rs.getBlob("image");//getting image from database 
                  imgData = image.getBytes(1,(int)image.length()); //extra info about image
                } 

response.setContentType("image/gif");//setting response type



OutputStream o = response.getOutputStream();

o.write(imgData);//sending the image to jsp page 
o.flush();
o.close();


 }
    catch(Exception e)
         {
             e.printStackTrace();

         }

Also this is not complete code,make changes as per your requirements .also don't forget to add jar's file

Hope this helps!