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Wednesday, November 23, 2011

Display Blob(Image) from Mysql table using JSP


In this section, we will display blob data(image) from Mysql database table using JSP code.
A Blob stores a binary large object in the database table's row. Blob object contains a logical pointer which points to the Blob data, data is not directly stored in the row of the database table. Blob object  is valid for the duration of the transaction. The "getBlob()" and  "setBlob()" method of "ResultSet" ,"CallableStatement", and "PreparedStatement" interface , is used for accessing Blob value.
The Method defined in " java.sql.Blob " interface is as follows--
Return Type    Method                                         Description 

InputStream        getBinaryStream()                       Retrieves the blob value designated
                                                                                 by this blob value as a stream

byte[]                 getBytes(long pos, int length)         Retrieve all or part of the blob value that
                                                                                 this blob represents as an array of bytes.

long                    length()                                          Returns the no of bytes in the Blob
                                                                                 value designated by this Blob object

OutputStream     setBinaryStream(long pos)           Retrieves a stream that can be used
                                                                                 to write to the Blob value 

int                       setBytes(long pos, byte[] bytes)    Write the given array of bytes to the Blob
                                                                                 value that this Blob object represent
                                                                                 starting at  position pos, and returns the no
                                                                                 of bytes written 

void                    truncate(long len)                            Truncates the blob value that this blob
                                                                                  object represents to be len bytes in len

Blob data type can further be classified into four types--
  • TINYBLOB: The maximum length is 255 characters (8 bits)
  • BLOB: The maximum length is 16,535 characters (16 bits)
  • MEDIUMBLOB: The maximum length is 16,777,216 characters (24 bits)
  • LONGBLOB: The maximum length is 4,294,967,295 characters (32 bits).
EXAMPLE :
displayblob.jsp
<%@ page import="java.sql.*"%>
<%@ page import="java.io.*"%>
<% Blob image = null;
Connection con = null;
byte[ ] imgData = null ;
Statement stmt = null;
ResultSet rs = null;
try {
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection("jdbc:mysql://192.168.10.13:3306/ankdb","root","root");
stmt = con.createStatement();
rs = stmt.executeQuery("select image from inimage where id = '6'");
if (rs.next()) {
image = rs.getBlob(1);
imgData = image.getBytes(1,(int)image.length());
else {
out.println("Display Blob Example");
out.println("image not found for given id>");
return;
}
// display the image
response.setContentType("image/gif");
OutputStream o = response.getOutputStream();
o.write(imgData);
o.flush();
o.close();
catch (Exception e) {
out.println("Unable To Display image");
out.println("Image Display Error=" + e.getMessage());
return;
finally {
try {
rs.close();
stmt.close();
con.close();
catch (SQLException e) {
e.printStackTrace();
}
}
%>
OUTPUT :
Related Tags for Display Blob(Image) from Mysql table using JSP :

from: http://www.roseindia.net/tutorial/java/jsp/jspdisplayblob.html

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