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How can we retrieve a blob datatype from a table using the getBinaryStream() method in JDBC?
The ResultSet interface provides the method named getBlob() to retrieve blob datatype from a table in the database. In addition to this, it also provides a method named getBinaryStream()
Like getBlob() this method also accepts an integer representing the index of the column (or, a String value representing the name of the column) and retrieves the value at the specified column. The difference is unlike the getBlob() method (which returns a Blob object) this method returns an InputStream object which holds the contents of the blob datatype in the form of un-interpreted bytes.
Example
Assume we have created a table named MyTable in the database with the following description.
+-------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+--------------+------+-----+---------+-------+ | Name | varchar(255) | YES | | NULL | | | image | blob | YES | | NULL | | +-------+--------------+------+-----+---------+-------+
And, we have inserted an image in it with name sample_image. Following program retrieves the contents of the MyTable using the getString() and getBinaryStream() methods.
import java.io.FileOutputStream;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class RetrievingBlob_ByteStream {
public static void main(String args[]) throws Exception {
//Registering the Driver
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
//Getting the connection
String mysqlUrl = "jdbc:mysql://localhost/sampleDB";
Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
System.out.println("Connection established......");
//Creating a Statement object
Statement stmt = con.createStatement();
//retrieving the data
ResultSet rs = stmt.executeQuery("select * from MyTable");
int i = 0;
System.out.println("Contents of the table");
while(rs.next()) {
System.out.println(rs.getString("Name"));
InputStream inputStream = rs.getBinaryStream("image");
byte byteArray[] = new byte[inputStream.available()];
inputStream.read(byteArray);
FileOutputStream outPutStream = new
FileOutputStream("E:\images\blob_output"+i+".jpg");
outPutStream.write(byteArray);
System.out.println("E:\images\blob_output"+i+".jpg");
}
}
}Output
Connection established...... Contents of the table sample_image E:\images\blob_output0.jpg
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